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<title>ProFTPD module mod_tls</title>
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<h2><b>ProFTPD module <code>mod_tls</code></b></h2>
</center>
<hr><br>
This module is contained in the <code>mod_tls.c</code> file for ProFTPD
1.3.<i>x</i>, and is not compiled by default. Installation
instructions are discussed <a href="#Installation">here</a>.
<p>
The most current version of <code>mod_tls</code> is distributed with the
ProFTPD source code.
<p>
This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/).
<p>
This product includes cryptographic software written by Eric Young (eay@cryptsoft.com).
<h2>Author</h2>
<p>
Please contact TJ Saunders <tj <i>at</i> castaglia.org> with any
questions, concerns, or suggestions regarding this module.
<h2>Thanks</h2>
<p>
<i>2002-09-01</i>: Thanks to Peter 'Luna' Runestig <peter <i>at</i>
runestig.com> for his original <code>mod_tls</code>, upon which this version
is based. His module can be found here:
<pre>
<a href="ftp://ftp.runestig.com/pub/proftpd-tls/">ftp://ftp.runestig.com/pub/proftpd-tls/</a>
</pre>
<h2>Directives</h2>
<ul>
<li><a href="#TLSCACertificateFile">TLSCACertificateFile</a>
<li><a href="#TLSCACertificatePath">TLSCACertificatePath</a>
<li><a href="#TLSCARevocationFile">TLSCARevocationFile</a>
<li><a href="#TLSCARevocationPath">TLSCARevocationPath</a>
<li><a href="#TLSCertificateChainFile">TLSCertificateChainFile</a>
<li><a href="#TLSCipherSuite">TLSCipherSuite</a>
<li><a href="#TLSControlsACLs">TLSControlsACLs</a>
<li><a href="#TLSCryptoDevice">TLSCryptoDevice</a>
<li><a href="#TLSDHParamFile">TLSDHParamFile</a>
<li><a href="#TLSDSACertificateFile">TLSDSACertificateFile</a>
<li><a href="#TLSDSACertificateKeyFile">TLSDSACertificateKeyFile</a>
<li><a href="#TLSECCertificateFile">TLSECACertificateFile</a>
<li><a href="#TLSECCertificateKeyFile">TLSECCertificateKeyFile</a>
<li><a href="#TLSEngine">TLSEngine</a>
<li><a href="#TLSLog">TLSLog</a>
<li><a href="#TLSMasqueradeAddress">TLSMasqueradeAddress</a>
<li><a href="#TLSOptions">TLSOptions</a>
<li><a href="#TLSPKCS12File">TLSPKCS12File</a>
<li><a href="#TLSPassPhraseProvider">TLSPassPhraseProvider</a>
<li><a href="#TLSProtocol">TLSProtocol</a>
<li><a href="#TLSRandomSeed">TLSRandomSeed</a>
<li><a href="#TLSRenegotiate">TLSRenegotiate</a>
<li><a href="#TLSRequired">TLSRequired</a>
<li><a href="#TLSRSACertificateFile">TLSRSACertificateFile</a>
<li><a href="#TLSRSACertificateKeyFile">TLSRSACertificateKeyFile</a>
<li><a href="#TLSServerCipherPreference">TLSServerCipherPreference</a>
<li><a href="#TLSSessionCache">TLSSessionCache</a>
<li><a href="#TLSTimeoutHandshake">TLSTimeoutHandshake</a>
<li><a href="#TLSUserName">TLSUserName</a>
<li><a href="#TLSVerifyClient">TLSVerifyClient</a>
<li><a href="#TLSVerifyDepth">TLSVerifyDepth</a>
<li><a href="#TLSVerifyOrder">TLSVerifyOrder</a>
<li><a href="#TLSVerifyServer">TLSVerifyServer</a>
</ul>
<h2>Control Actions</h2>
<ul>
<li><a href="#tls_sesscache_clear"><code>tls sesscache clear</code></a>
<li><a href="#tls_sesscache_info"><code>tls sesscache info</code></a>
<li><a href="#tls_sesscache_remove"><code>tls sesscache remove</code></a>
</ul>
<hr>
<h2><a name="TLSCACertificateFile">TLSCACertificateFile</a></h2>
<strong>Syntax:</strong> TLSCACertificateFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSCACertificateFile</code> directive configures one file where you
can assemble the certificates of Certification Authorities (CA) for your
clients. The CA certificates in the file are then used to verify client
certificates, if presented. Such a file is merely the concatenation of the
various PEM-encoded CA certificates, in order of preference. This directive
can be used in addition to, or as an alternative for,
<code>TLSCACertificatePath</code>.
<p>
Example:
<pre>
TLSCACertificateFile /etc/ftpd/ca-bundle.pem
</pre>
<p>
If neither <code>TLSCACertificateFile</code> nor
<code>TLSCACertificatePath</code> are specified, the following message will
appear in the <code>TLSLog</code>:
<pre>
using default OpenSSL verification locations (see $SSL_CERT_DIR)
</pre>
This means that the <code>SSL_CERT_DIR</code> environment variable, if set,
will be used to determine the location of a CA certificate directory, to be
used when verifying clients. Note, though, that this directive is only
meaningful if <code>TLSVerifyClient</code> is set to <em>on</em>; otherwise,
no client verification occurs.
<p>
See also: <a href="#TLSCACertificatePath"><code>TLSCACertificatePath</code></a>
<p>
<hr>
<h2><a name="TLSCACertificatePath">TLSCACertificatePath</a></h2>
<strong>Syntax:</strong> TLSCACertificatePath <em>directory</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSCACertificatePath</code> directive sets the directory for the
certificates of Certification Authorities (CAs) for your clients. These are
used to verify the client certificates presented. This directive may be used
in addition to, or as alternative for, <code>TLSCACertificateFile</code>.
<p>
The files in the configured directory have to be PEM-encoded, and are accessed
through hash filenames. This means one cannot simply place the CA certificates
there: one also has to create symbolic links named <i>hash-value</i>.N. The
<code>c_rehash</code> utility that comes with OpenSSL can be used to create
the necessary symlinks.
<p>
Example:
<pre>
TLSCACertificatePath /etc/ftpd/ca/
</pre>
<p>
If neither <code>TLSCACertificateFile</code> nor
<code>TLSCACertificatePath</code> are specified, the following message will
appear in the <code>TLSLog</code>:
<pre>
using default OpenSSL verification locations (see $SSL_CERT_DIR)
</pre>
This means that the <code>SSL_CERT_DIR</code> environment variable, if set,
will be used to determine the location of a CA certificate directory, to be
used when verifying clients.
<p>
See also: <a href="#TLSCACertificateFile"><code>TLSCACertificateFile</code></a>
<p>
<hr>
<h2><a name="TLSCARevocationFile">TLSCARevocationFile</a></h2>
<strong>Syntax:</strong> TLSCARevocationFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSCARevocationFile</code> directive configures one file that can
contain the Certificate Revocation Lists (CRL) of Certification Authorities
(CA) for your clients. These CRLs are used during the verification of client
certificates, if presented. Such a file is merely the concatenation of the
various PEM-encoded CRL files, in order of preference. This directive can be
used in addition to, or as an alternative for, <code>TLSCARevocationPath</code>.
<p>
Example:
<pre>
TLSCARevocationFile /etc/ftpd/ca-crl-bundle.pem
</pre>
<p>
See also: <a href="#TLSCARevocationPath"><code>TLSCARevocationPath</code></a>
<p>
<hr>
<h2><a name="TLSCARevocationPath">TLSCARevocationPath</a></h2>
<strong>Syntax:</strong> TLSCARevocationPath <em>directory</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSCARevocationPath</code> directive sets the directory for the
Certificate Revocation Lists (CRL) of Certification Authorities (CAs) for your
clients. These are used during the verification of client certificates, if
presented. This directive may be used in addition to, or as alternative for,
<code>TLSCARevocationFile</code>.
<p>
The files in the configured directory have to be PEM-encoded, and are accessed
through hash filenames. This means one cannot simply place the CRLs there:
one also has to create symbolic links named <i>hash-value</i>.N. The
<code>c_rehash</code> utility that comes with OpenSSL can be used to create
the necessary symlinks.
<p>
Example:
<pre>
TLSCARevocationPath /etc/ftpd/crl/
</pre>
<p>
See also: <a href="#TLSCARevocationFile"><code>TLSCARevocationFile</code></a>
<p>
<hr>
<h2><a name="TLSCertificateChainFile">TLSCertificateChainFile</a></h2>
<strong>Syntax:</strong> TLSCertificateChainFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSCertificateChainFile</code> directive sets the optional
all-in-one file where you can assemble the certificates of Certification
Authorities (CA) which form the certificate chain of the server certificate.
This starts with the issuing CA certificate of the server certificate and can
range up to the root CA certificate. Such a file is simply the concatenation
of the various PEM-encoded CA Certificate files in certificate chain order.
(<em>Certificate chain order</em> means that the list must be sorted starting
with the subject's certificate (actual server certificate), followed by
intermediate CA certificates if applicable, and ending at the highest level
root CA.) This server certificate chain is sent to the client, in addition to
the server's certificate.
<p>
If <code>TLSCertificateChainFile</code> is not used, and
<code>TLSCACertificatePath</code> is used, the certificate chain is built from
the certificates in that path. <code>TLSCertificateChainFile</code> should be
used as an alternative to <code>TLSCACertificatePath</code> for explicitly
constructing the server certificate chain. It is especially useful to avoid
conflicts with CA certificates when using client authentication. For although
placing a CA certificate of the server certificate chain into
the <code>TLSCACertificatePath</code> has the same effect for the certificate
chain construction, it has the side-effect that client certificates issued by
this same CA certificate are also accepted on client authentication. This
is usually <i>not</i> what one expects.
<p>
Be careful: providing the certificate chain works only if you are using a
single (either RSA or DSA) based server certificate. If you are using a coupled
RSA+DSA certificate pair, this will work only if actually both certificates
use the same certificate chain. Otherwise, clients will become confused.
<p>
Example:
<pre>
TLSCertificateChainFile /etc/ftpd/client-ca-list.pem
</pre>
<p>
<b>Note</b>: If you use the <code>NoCertRequest</code>
<a href="#TLSOptions"><code>TLSOption</code></a>, then any configured
<code>TLSCertificateChainFile</code> directive will be ignored. It is a waste
of time to construct a certificate chain to send to the client if the server
does not request that the client send a certificate to be verified.
<p>
<hr>
<h2><a name="TLSCipherSuite">TLSCipherSuite</a></h2>
<strong>Syntax:</strong> TLSCipherSuite <em>cipher-list</em><br>
<strong>Default:</strong> DEFAULT:!EXPORT:!DES<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
Default cipher list is "DEFAULT:!EXPORT:!DES".
<p>
How to put together a <em>cipher list</em> parameter:
<pre>
Key Exchange Algorithms:
"kRSA" RSA key exchange
"kDHr" Diffie-Hellman key exchange (key from RSA cert)
"kDHd" Diffie-Hellman key exchange (key from DSA cert)
"kEDH' Ephemeral Diffie-Hellman key exchange (temporary key)
Authentication Algorithm:
"aNULL" No authentication
"aRSA" RSA authentication
"aDSS" DSS authentication
"aDH" Diffie-Hellman authentication
Cipher Encoding Algorithm:
"eNULL" No encodiing
"DES" DES encoding
"3DES" Triple DES encoding
"RC4" RC4 encoding
"RC2" RC2 encoding
"IDEA" IDEA encoding
MAC Digest Algorithm:
"MD5" MD5 hash function
"SHA1" SHA1 hash function
"SHA" SHA hash function (should not be used)
Aliases:
"ALL" all ciphers
"SSLv2" all SSL version 2.0 ciphers (should not be used)
"SSLv3" all SSL version 3.0 ciphers
"EXP" all export ciphers (40-bit)
"EXPORT56" all export ciphers (56-bit)
"LOW" all low strength ciphers (no export)
"MEDIUM" all ciphers with 128-bit encryption
"HIGH" all ciphers using greater than 128-bit encryption
"RSA" all ciphers using RSA key exchange
"DH" all ciphers using Diffie-Hellman key exchange
"EDH" all ciphers using Ephemeral Diffie-Hellman key exchange
"ADH" all ciphers using Anonymous Diffie-Hellman key exchange
"DSS" all ciphers using DSS authentication
"NULL" all ciphers using no encryption
</pre>
<p>
Each item in the list may include a prefix modifier:
<pre>
"+" move cipher(s) to the current location in the list
"-" remove cipher(s) from the list (may be added again by a
subsequent list entry)
"!" kill cipher from the list (it may not be added again by a
subsequent list entry)
</pre>
<p>
If no modifier is specified the entry is added to the list at the current
position. "+" may also be used to combine tags to specify entries
such as "RSA+RC4" describes all ciphers that use both RSA and RC4.
<p>
For example, all available ciphers not including ADH key exchange:
<pre>
ALL:!ADH:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv2:+EXP
</pre>
<p>
All algorithms including ADH and export but excluding patented algorithms:
<pre>
HIGH:MEDIUM:LOW:EXPORT56:EXP:ADH:!kRSA:!aRSA:!RC4:!RC2:!IDEA
</pre>
<p>
The OpenSSL command
<pre>
openssl ciphers -v <em><list of ciphers></em>
</pre>
may be used to list all of the ciphers and the order described by a specific
<em><list of ciphers></em>.
<p>
<hr>
<h2><a name="TLSControlsACLs">TLSControlsACLs</a></h2>
<strong>Syntax:</strong> TLSControlsACLs <em>actions|"all" "allow"|"deny" "user"|"group" list</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config<br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.3rc1 and later
<p>
The <code>TLSControlsACLs</code> directive configures access lists of
<em>users</em> or <em>groups</em> who are allowed (or denied) the ability to
use the <em>actions</em> implemented by <code>mod_tls</code>. The default
behavior is to deny everyone unless an ACL allowing access has been explicitly
configured.
<p>
If "allow" is used, then <em>list</em>, a comma-delimited list
of <em>users</em> or <em>groups</em>, can use the given <em>actions</em>; all
others are denied. If "deny" is used, then the <em>list</em> of
<em>users</em> or <em>groups</em> cannot use <em>actions</em> all others are
allowed. Multiple <code>TLSControlsACLs</code> directives may be used to
configure ACLs for different control actions, and for both users and groups.
<p>
The <em>actions</em> provided by <code>mod_tls</code> are
"sesscache clear" , "sesscache info", and
"sesscache remove".
<p>
Examples:
<pre>
# Allow only user root to examine/update the external SSL session cache
TLSControlsACLs all allow user root
</pre>
<p>
<hr>
<h2><a name="TLSCryptoDevice">TLSCryptoDevice</a></h2>
<strong>Syntax:</strong> TLSCryptoDevice <em>driver|"all"|"none"</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>TLSCryptoDevice</code> directive is used to configure
<code>mod_tls</code> to use an OpenSSL "engine", a cryptographic module
that OpenSSL library can use for accelerated cryptographic support, or
HSM keys, <i>etc</i>.
<p>
To use all of the engines compiled into OpenSSL, use:
<pre>
TLSCryptoDevice all
</pre>
OpenSSL will find, from the list of supported engines, the first one
usable, if any. If no usable engines are found, OpenSSL will default to
its normal software implementation. If a specific engine is desired as
the default engine to use, specify the engine name, <i>e.g.</i>:
<pre>
TLSCryptoDevice chil
</pre>
<p>
The OpenSSL command
<pre>
openssl engine
</pre>
may be used to list all of the engine drivers supported by OpenSSL.
<p>
<hr>
<h2><a name="TLSDHParamFile">TLSDHParamFile</a></h2>
<strong>Syntax:</strong> TLSDHParamFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSDHParamFile</code> directive is used to configure a file that
contains pre-computed Diffie-Hellman (DH) group parameters. The
<code>mod_tls</code> module will use these parameters when engaging in
Diffie-Hellman key exchanges.
<p>
Such key exchanges can be computationally intensive, in terms for parameter
generation. To help speed up the process and avoid latency for Diffie-Hellman
key exchanges, the DH group parameters used may be generated in advance, and
stored in a <code>TLSDHParamFile</code>. The <code>dhparam</code> utility
that comes with OpenSSL may be used to generate an appropriate file for this
directive:
<pre>
# openssl dhparam -outform PEM -2 <i>nbits</i> >> dhparams.pem
# openssl dhparam -outform PEM -5 <i>nbits</i> >> dhparams.pem
<pre>
Using either -2 or -5 as the generator is fine. The <em>nbits</em> value used
should vary between 512 and 4096, inclusive.
<p>
The <em>file</em> parameter must be an absolute path.
<p>
<hr>
<h2><a name="TLSDSACertficateFile">TLSDSACertficateFile</a></h2>
<strong>Syntax:</strong> TLSDSACertificateFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSDSACertificateFile</code> directive points to the PEM-encoded
file containing the DSA certificate file for the server and optionally also
the corresponding DSA private key file.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted. Alternatively, the <code>TLSPassPhraseProvider</code>
directive can be used to supply a source for that passphrase.
<p>
Example:
<pre>
TLSDSACertificateFile /etc/ftpd/server-dsa-cert.pem
</pre>
<p>
<hr>
<h2><a name="TLSDSACertificateKeyFile">TLSDSACertificateKeyFile</a></h2>
<strong>Syntax:</strong> TLSDSACertificateKeyFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSDSACertificateKeyFile</code> directive points to the PEM-encoded
private key file for the server. If the private key is not combined with the
certificate in the <code>TLSDSACertificateFile</code>, use this additional
directive to point to the file with the standalone private key. When
<code>TLSDSACertificateFile</code> is used and the file contains both the
certificate and the private key, this directive need not be used. However,
this practice is strongly discouraged. Instead we recommend you to separate
the certificate and the private key.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted.
<p>
Example:
<pre>
TLSDSACertificateKeyFile /etc/ftpd/server-dsa-key.pem
</pre>
<p>
<hr>
<h2><a name="TLSECCertficateFile">TLSECCertficateFile</a></h2>
<strong>Syntax:</strong> TLSECCertificateFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc4 and later
<p>
The <code>TLSECCertificateFile</code> directive points to the PEM-encoded
file containing the EC certificate file for the server and optionally also
the corresponding EC private key file.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted. Alternatively, the <code>TLSPassPhraseProvider</code>
directive can be used to supply a source for that passphrase.
<p>
Example:
<pre>
TLSECCertificateFile /etc/ftpd/server-ec-cert.pem
</pre>
<p>
<hr>
<h2><a name="TLSECCertificateKeyFile">TLSECCertificateKeyFile</a></h2>
<strong>Syntax:</strong> TLSECCertificateKeyFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc4 and later
<p>
The <code>TLSECCertificateKeyFile</code> directive points to the PEM-encoded
private key file for the server. If the private key is not combined with the
certificate in the <code>TLSECCertificateFile</code>, use this additional
directive to point to the file with the standalone private key. When
<code>TLSECCertificateFile</code> is used and the file contains both the
certificate and the private key, this directive need not be used. However,
this practice is strongly discouraged. Instead we recommend you to separate
the certificate and the private key.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted.
<p>
Example:
<pre>
TLSECCertificateKeyFile /etc/ftpd/server-ec-key.pem
</pre>
<p>
<hr>
<h2><a name="TLSEngine">TLSEngine</a></h2>
<strong>Syntax:</strong> TLSEngine <em>on|off</em><br>
<strong>Default:</strong> off<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSEngine</code> directive toggles the use of the SSL/TLS protocol
engine (<i>e.g.</i> <code>mod_tls</code>). This is usually used inside a
<code><VirtualHost></code> section to enable SSL/TLS sessions for a
particular virtual host. By default <code>mod_tls</code> is disabled for both
the main server and all configured virtual hosts.
<p>
<hr>
<h2><a name="TLSLog">TLSLog</a></h2>
<strong>Syntax:</strong> TLSLog <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSLog</code> directive is used to specify a log file for
<code>mod_tls</code>'s reporting on a per-server basis. The <em>file</em>
parameter given must be the full path to the file to use for logging.
<p>
Note that this path must <b>not</b> be to a world-writable directory and,
unless <code>AllowLogSymlinks</code> is explicitly set to <em>on</em>
(generally a bad idea), the path must <b>not</b> be a symbolic link.
<p>
<hr>
<h2><a name="TLSMasqueradeAddress">TLSMasqueradeAddress</a></h2>
<strong>Syntax:</strong> TLSMasqueradeAddress <em>ip-address|dns-name|device-name</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc2 and later
<p>
The <code>TLSMasqueradeAddress</code> directive functions exactly like the
<a href="../modules/mod_core.html#MasqueradeAddress"><code>MasqueradeAddress</code></a>, except that it applies <b>only to FTPS sessions</b>. (Note that if
<em>both</em> <code>MasqueradeAddress</code> <b>and</b>
<code>TLSMasqueradeAddress</code> are configured, then the
<code>TLSMasqueradeAddress</code> directive will take precedence, but only
for FTPS sessions.)
<p>
<b><i>Discussion</i></b><br>
Why is something like <code>TLSMasqueradeAddress</code> needed? There are
cases where some sites run <code>proftpd</code> within a restricted VLAN/DMZ,
with some sort of firewall/proxy/router device which handles FTP and FTPS
connections from the Internet to that <code>proftpd</code> server:
<pre>
<i>client</i> <---> <i>firewall</i> <---> <i>load balancer</i> <---> <i>server</i>
</pre>
In many cases, the firewall/proxy/router device will look at the FTP responses
for the <code>PASV</code>/<code>EPSV</code> commands (in which
<code>proftpd</code> may be sending its internal, non-public IP address), and
rewrite the responses to have the IP address of the firewall/proxy/router
device.
<p>
Normally, the <code>MasqueradeAddress</code> directive can be used for such
cases, so that <code>proftpd</code> sends the configured address in the
<code>PASV</code>/<code>EPSV</code> responses. With that configuration,
the firewall/proxy/router device will not need to rewrite the responses.
And this approach works for FTPS sessions as well, where the
firewall/proxy/router device <b><i>cannot</i></b> rewrite the response due to
the SSL/TLS protection.
<p>
Sometimes, though, sites <b>want</b> their firewall/proxy/router device to be
able to properly rewrite FTP responses. But due to bugs/implementation details
in the firewall/proxy/router devices, <i>if</i> a
<code>PASV</code>/<code>EPSV</code> response contains a public IP address, the
device will drop/break that FTP connection.
<p>
This leaves the site in a case where it does <b>not</b> want to use
<code>MasqueradeAddress</code> (so that the device can properly rewrite FTP
responses), which works -- but only for plain FTP sessions. Yet the site
<b>does</b> want to use <code>MasqueradeAddress</code> -- but only for FTPS
sessions, since the device cannot rewrite FTPS responses.
<p>
For these situations, then, the <code>TLSMasqueradeAddress</code> directive
can/should be used: it provides <code>MasqueradeAddress</code> functionality,
but only for FTPS sessions.
<p>
<hr>
<h2><a name="TLSOptions">TLSOptions</a></h2>
<strong>Syntax:</strong> TLSOptions <em>opt1 ...</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSOptions</code> directive is used to configure various optional
behavior of <code>mod_tls</code>. <b>Note</b>: all of the configured
<code>TLSOptions</code> parameters <b>must</b> appear on the same line in
the configuration; only the first <code>TLSOptions</code> directive that
appears in the configuration is used.
<p>
Example:
<pre>
TLSOptions iPAddressRequired StdEnvVars NoSessionReuseRequired
</pre>
<p>
The currently implemented options are:
<ul>
<li><code>AllowClientRenegotiations</code><br>
<p>
The <code>mod_tls</code> will reject any SSL/TLS session renegotiation
attempts by the client, in order to mitigate any issues arising from the
<a href="http://www.educatedguesswork.org/2009/11/understanding_the_tls_renegoti.html">SSL/TLS session renegotiation vulnerability</a> (CVE-2009-3555)
or <a href="http://www.ietf.org/mail-archive/web/tls/current/msg07553.html">SSL/TLS session renegotiation DoS</a> (CVE-2011-1473). If, however, your
particular site or clients absolutely require support for client-initiated
SSL/TLS session renegotiations, then this option can be used.
<b>Not recommended.</b>
<p>
Note, however, that SSL/TLS session renegotiation requests that are
initiated by <code>mod_tls</code>, via the
<a href="#TLSRenegotiate"><code>TLSRenegotiate</code></a> directive, are
still handled (depending on the OpenSSL version).
<li><code>AllowDotLogin</code><br>
<p>
By default, <code>mod_tls</code> still requires that a user supply a
password for authentication, even if a valid client certificate is
presented. If this option is enabled, <code>mod_tls</code> will check
in the user's home directory for a <code>.tlslogin</code> file, which
should contain one or more PEM-encoded certificates. If the certificate
presented by the client, if any, matches a certificate in this
<code>.tlslogin</code> file, the user will be considered authenticated
and the server will not prompt for a password. If the user's
<code>.tlslogin</code> does not exist, or does not contain the client's
certificate, then the server will fallback to requesting a password for
authentication.
<p>
<li><code>AllowPerUser</code><br>
<p>
This option affects how <code>mod_tls</code> evaluates any
<code>TLSRequired</code> directives. Usually <code>mod_tls</code>
will reject any FTP commands, when <code>TLSRequired on</code> or
<code>TLSRequired ctrl</code> is in effect, if the client has not
successfully negotiated a SSL/TLS handshake. The FTPS specification
requires that the SSL/TLS handshake occur, via the AUTH FTP command,
<i>before</i> the USER and PASS commands. This means that
<code>mod_tls</code> does not know the identity of the connecting client
when enforcing <code>TLSRequired</code>. If this <code>AllowPerUser</code>
is used, <code>mod_tls</code> will wait until after the <code>PASS</code>
command has been processed to enforce any <code>TLSRequired</code>
settings.
<p>
<b>Important</b>: if <code>AllowPerUser</code> is used, even if
<code>TLSRequired on</code> or <code>TLSRequired ctrl</code> are in
effect, it will be possible for the connecting client to send
usernames and password <i>unprotected</i> before <code>mod_tls</code>
rejects the connection. This results in a slightly weaker security
policy enforcement; please consider carefully if this tradeoff is
acceptable for your site.
<p>
However, <code>TLSRequired auth</code> and
<code>TLSRequired auth+data</code> configurations will override the
<code>AllowPerUser</code> option.
<p>
<li><code>CommonNameRequired</code><br>
<p>
This option will cause <code>mod_tls</code> to perform checks on a client's
certificate once the SSL handshake has been completed: the client's
certificate will be searched for the <code>CommonName</code> (CN) X509v3
value. Unless a <code>CommonName</code> value is present, and the
value matches the DNS name to which the client's IP address resolves,
the SSL session is closed. This check is only performed during
SSL handshakes on the control channel. Note that if
<code>UseReverseDNS</code> is <em>off</em>, this option is automatically
disabled.
<p>
<li><code>EnableDiags</code><br>
Sets callbacks in the OpenSSL library such that <b>a lot</b> of
SSL/TLS protcol information is logged to the
<a href="#TLSLog"><code>TLSLog</code></a> file. This option is very
useful when debugging strange interactions with FTPS clients.
<p>
<li><code>ExportCertData</code><br>
<p>
Sets the following environment variables, if applicable. Note that
doing so increases the memory size of the process quite a bit:
<table border=1>
<tr>
<td><code>TLS_SERVER_CERT</code></td>
<td>Server certificate, PEM-encoded</td>
</tr>
<tr>
<td><code>TLS_CLIENT_CERT</code></td>
<td>Client certificate, PEM-encoded</td>
</tr>
<tr>
<td><code>TLS_CLIENT_CERT_CHAIN<i>n</i></code></td>
<td>PEM-encoded certificates in client certificate chain</td>
</tr>
</table>
<p>
<li><code>NoCertRequest</code><br>
<p>
Some FTP clients are known to be buggy when handling a server's certificate
request. This option causes the server to <b>not</b> send such a request
during an SSL handshake.
<p>
<li><code>NoEmptyFragments</code><br>
<p>
In order to prevent certain attacks (<i>e.g.</i> the so-called
<a href="http://www.kb.cert.org/vuls/id/864643">"BEAST"
attack</a>), the <code>mod_tls</code> module was changed to use OpenSSL's
builtin countermeasure of inserting <a href="http://www.openssl.org/~bodo/tls-cbc.txt">empty fragments</a>. However, some browsers/clients may not handle
such empty fragments well. Use this <code>NoEmptyFragaments</code>
TLSOption in order to interoperate with such clients, with risk of losing
the protective countermeasure.
<p>
Note that this protective countermeasure only applies to SSLv3 and TLSv1
sessions; it does not affect TLSv1.1 or TLSv1.2 sessions.
<p>
Added in ProFTPD 1.3.4rc4.
<p>
<li><code>NoSessionReuseRequired</code><br>
<p>
As of ProFTPD 1.3.3rc1, <code>mod_tls</code> only accepts SSL/TLS data
connections that reuse the SSL session of the control connection, as a
security measure. Unfortunately, there are some clients (<i>e.g.</i>
curl) which do not reuse SSL sessions.
<p>
To relax the requirement that the SSL session from the control connection
be reused for data connections, use the following in the proftpd.conf:
<pre>
<IfModule mod_tls.c>
...
TLSOptions NoSessionReuseRequired
...
</IfModule>
</pre>
<p>
<li><code>StdEnvVars</code><br>
<p>
Sets the following environment variables, if applicable. These environment
variables are then avaiable for use, such as in <code>LogFormat</code>s.
Note that doing so may increase the memory size of the process quite a bit:
<table border=1>
<tr>
<td><code>FTPS</code></td>
<td>Present if FTP over SSL/TLS is being used</td>
</tr>
<tr>
<td><code>TLS_PROTOCOL</code></td>
<td>SSL protocol version (<i>e.g.</i> SSLv3, TLSv1)</td>
</tr>
<tr>
<td><code>TLS_SESSION_ID</code></td>
<td>Hex-encoded SSL session ID</td>
</tr>
<tr>
<td><code>TLS_CIPHER</code></td>
<td>Cipher specification name</td>
</tr>
<tr>
<td><code>TLS_CIPHER_EXPORT</code></td>
<td>Present if cipher is an export cipher</td>
</tr>
<tr>
<td><code>TLS_CIPHER_KEYSIZE_POSSIBLE</code></td>
<td>Number of cipher bits possible</td>
</tr>
<tr>
<td><code>TLS_CIPHER_KEYSIZE_USED</code></td>
<td>Number of cipher bits used</td>
</tr>
<tr>
<td><code>TLS_LIBRARY_VERSION</code></td>
<td>OpenSSL version</td>
</tr>
<tr>
<td><code>TLS_CLIENT_M_VERSION</code></td>
<td>Client certificate version</td>
</tr>
<tr>
<td><code>TLS_CLIENT_M_SERIAL</code></td>
<td>Client certificate serial number</td>
</tr>
<tr>
<td><code>TLS_CLIENT_S_DN</code></td>
<td>Subject DN of client certificate</td>
</tr>
<tr>
<td><code>TLS_CLIENT_S_DN_</code><i>x509<i></td>
<td>Component of client certificate's Subject DN, where <i>x509</i> is
a component of a X509 DN:<br>
C,CN,D,I,G,L,O,OU,S,ST,T,UID,Email</td>
</tr>
<tr>
<td><code>TLS_CLIENT_I_DN</code></td>
<td>Issuer DN of client certificate</td>
</tr>
<tr>
<td><code>TLS_CLIENT_I_DN_</code><i>x509</i></td>
<td>Component of client certificate's Issuer DN, where <i>x509</i> is
a component of a X509 DN:<br>
C,CN,D,I,G,L,O,OU,S,ST,T,UID,Email</td>
</tr>
<tr>
<td><code>TLS_CLIENT_V_START</code></td>
<td>Start time of client certificate validity</td>
</tr>
<tr>
<td><code>TLS_CLIENT_V_END</code></td>
<td>End time of client certificate validity</td>
</tr>
<tr>
<td><code>TLS_CLIENT_A_SIG</code></td>
<td>Client certificate's signature algorithm</td>
</tr>
<tr>
<td><code>TLS_CLIENT_A_KEY</code></td>
<td>Client certificate's public key algorithm</td>
</tr>
<tr>
<td><code>TLS_CLIENT_CERT</code>
<td>Client certificate, PEM-encoded</td>
</tr>
<tr>
<td><code>TLS_CLIENT_CERT_CHAIN<i>n</i></code></td>
<td>PEM-encoded certificates in client certificate chain</td>
</tr>
<tr>
<td><code>TLS_SERVER_M_VERSION</code></td>
<td>Server certificate version</td>
</tr>
<tr>
<td><code>TLS_SERVER_M_SERIAL</code></td>
<td>Server certificate serial number</td>
</tr>
<tr>
<td><code>TLS_SERVER_S_DN</code></td>
<td>Subject DN of server certificate</td>
</tr>
<tr>
<td><code>TLS_SERVER_S_DN_</code><i>x509</i></td>
<td>Component of server certificate's Subject DN, where <i>x509</i> is
a component of a X509 DN:<br>
C,CN,D,I,G,L,O,OU,S,ST,T,UID,Email</td>
</tr>
<tr>
<td><code>TLS_SERVER_I_DN</code></td>
<td>Issuer DN of server certificate</td>
</tr>
<tr>
<td><code>TLS_SERVER_I_DN_</code><i>x509</i></td>
<td>Component of server certificate's Issuer DN, where <i>x509</i> is
a component of a X509 DN:<br>
C,CN,D,I,G,L,O,OU,S,ST,T,UID,Email</td>
</tr>
<tr>
<td><code>TLS_SERVER_V_START</code></td>
<td>Start time of server certificate validity</td>
</tr>
<tr>
<td><code>TLS_SERVER_V_END</code></td>
<td>End time of server certificate validity</td>
</tr>
<tr>
<td><code>TLS_SERVER_A_SIG</code></td>
<td>Server certificate's signature algorithm</td>
</tr>
<tr>
<td><code>TLS_SERVER_A_KEY</code></td>
<td>Server certificate's public key algorithm</td>
</tr>
<tr>
<td><code>TLS_SERVER_CERT</code></td>
<td>Server certificate, PEM-encoded</td>
</tr>
</table>
<p>
<li><code>UseImplicitSSL</code><br>
<p>
This option will cause the <code>mod_tls</code> module to handle <b>all</b>
connections as if they are SSL connections implicitly; the client does
<i>not</i> need to send the <code>AUTH TLS</code> FTP command. This can
cause issues for FTPS clients which are expecting explicit FTPS, not
implicit FTPS.
<p>
Thus if the <code>UseImplicitSSL</code> option is used, you will want to
have a separate <code><VirtualHost></code> section with
a different port number just for those clients which require/expect
implicit FTPS. For example:
<pre>
<IfModule mod_tls.c>
<VirtualHost a.b.c.d>
TLSEngine on
TLSOptions UseImplicitSSL
# The "standard" implicit FTPS port is 990
Port 990
...
</VirtualHost>
</IfModule>
</pre>
<p>
<li><code>dNSNameRequired</code><br>
<p>
This option will cause <code>mod_tls</code> to perform checks on a client's
certificate once the SSL handshake has been completed: the client's
certificate will be searched for the <code>subjectAltName</code> X509v3
extension, and, in that extension, the <code>dNSName</code> value will
be looked up. Unless a <code>dNSName</code> value is present, and the
value matches the DNS name to which the client's IP address resolves,
the SSL session is closed. This check is only performed during
SSL handshakes on the control channel. Note that if
<code>UseReverseDNS</code> is <em>off</em>, this option is automatically
disabled.
<p>
<li><code>iPAddressRequired</code><br>
<p>
This option will cause <code>mod_tls</code> to perform checks on a client's
certificate once the SSL handshake has been completed: the client's
certificate will be searched for the <code>subjectAltName</code> X509v3
extension, and, in that extension, the <code>iPAddress</code> value will
be looked up. Unless an <code>iPAddress</code> value is present, and the
value matches the IP address of the client, the SSL session is closed.
This check is only performed during SSL handshakes on the control channel.
</ul>
<p>
<hr>
<h2><a name="TLSPKCS12File">TLSPKCS12File</a></h2>
<strong>Syntax:</strong> TLSPKCS12File <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.3rc1 and later
<p>
The <code>TLSPKCS12ile</code> directive points to the PKCS#12 file containing
the certificate file and its private key for the server.
<p>
If the PKCS#12 file is protected with a passphrase, the administrator will
be prompted for the passphrase when the daemon starts up, and when the daemon
is restarted. Alternatively, the <code>TLSPassPhraseProvider</code>
directive can be used to supply a source for that passphrase.
<p>
Example:
<pre>
TLSPKCS12File /etc/ftpd/server-cert.p12
</pre>
<p>
<hr>
<h2><a name="TLSPassPhraseProvider">TLSPassPhraseProvider</a></h2>
<strong>Syntax:</strong> TLSPassPhraseProvider <em>path</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config<br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>TLSPassPhraseProvider</code> directive is used to specify an
external program which will be called, when <code>mod_tls</code> starts up,
for each encrypted certificate key file. The program will be invoked with
two command-line arguments, passed on <code>stdin</code> to the program:
<pre>
<em>servername</em>:<em>portnumber</em> "RSA"|"DSA"
</pre>
where <code><em>servername</em>:<em>portnumber</em></code> indicates the
server using that encrypted certificate key, and <code>"RSA"</code>
or <code>"DSA"</code> indicates the private key algorithm used
for that key. The program then must print the corresponding passphrase
for the key to <code>stdout</code>.
<p>
The intent is that this external program can perform any security checks
necessary, to make sure that the system is not compromised by an attacker,
and only when these checks pass successfully will the passphrase be provided.
These security checks, and the way the passphrase is determined, can be as
complex as you like.
<p>
Example:
<pre>
TLSPassPhraseProvider /etc/ftpd/tls/get-passphrase
</pre>
<p>
<hr>
<h2><a name="TLSProtocol">TLSProtocol</a></h2>
<strong>Syntax:</strong> TLSProtocol <em>protocol1</em> ... <em>protocolN</em><br>
<strong>Default:</strong> SSLv3 TLSv1<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSProtocol</code> directive is used to configure the SSL/TLS
protocol versions that <code>mod_tls</code> should use when establishing
SSL/TLS sessions. Clients can then only connect using the configured
protocol.
<p>
Since the protocol version used by <code>mod_tls</code> is set only once,
when the daemon starts, the <code>TLSProtocol</code> directive is only allowed
in the "server config" context.
<p>
The allowed protocols are:
<p>
<table>
<tr>
<td><code>SSLv3</code></td>
<td>Allow only SSLv3</td>
</tr>
<tr>
<td><code>TLSv1</code></td>
<td>Allow only TLSv1</td>
</tr>
<tr>
<td><code>TLSv1.1</code></td>
<td>Allow only TLSv1.1</td>
</tr>
<tr>
<td><code>TLSv1.2</code></td>
<td>Allow only TLSv1.2</td>
</tr>
</table>
To support both SSLv3 and TLSv1, simply list both parameters for the
<code>TLSProtocol</code> directive, <i>e.g.</i>:
<pre>
TLSProtocol SSLv3 TLSv1
</pre>
<p>
Note that the parameter "SSLv23" is supported as a legacy style for saying
"all versions".
<p>
All use of SSLv2 is disabled. SSLv2 <b>should not</b> be used.
<p>
<hr>
<h2><a name="TLSRandomSeed">TLSRandomSeed</a></h2>
<strong>Syntax:</strong> TLSRandomSeed <em>seed</em><br>
<strong>Default:</strong> <i>openssl-dir</i><code>/.rnd</code><br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSRandomSeed</code> directive configures the file that
<code>mod_tls</code> will use for seeding the PRNG. <em>seed</em> must be an
absolute path.
<p>
When the daemon shuts down, any random data left will be written out to the
random seed file, so that that data may be used for seeding when the daemon
is started again.
<p>
Example:
<pre>
TLSRandomSeed /etc/ftpd/server.rnd
</pre>
<p>
Note that the <code>TLSRandomSeed</code> directive is <b>not</b> used to
seed the entropy required by the OpenSSL library; that configuration
is OpenSSL-specific. Instead, the <code>TLSRandomSeed</code> file can
be thought of a cache file for the unused entropy, to be used to help
speed up entropy gathering when the daemon starts up again.
<p>
<hr>
<h2><a name="TLSRenegotiate">TLSRenegotiate</a></h2>
<strong>Syntax:</strong> TLSRenegotiate <em>["ctrl" secs] ["data" Kbytes] ["timeout" secs]|["required" on|off]|"none"</em><br>
<strong>Default:</strong> ctrl 14400 data 25165824 required true <i>(for OpenSSL 0.9.7 or greater)</i><br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSRenegotiate</code> directive is used to configure when SSL
renegotiations are to occur. Renegotiations, and thus this directive, are
only supported by <code>mod_tls</code> if the version of OpenSSL installed
is 0.9.7 or greater.
<p>
If supported, renegotiations will occur on control channels that have been
established for four hours by default, and on data channels that have
transferred over one gigabyte of data by default. When renegotiations are
requested, the client is given a timeout of 30 seconds, by default, to perform
the renegotiation. To change the default control channel renegotiation
timeout, use <em>ctrl</em> followed by a number, greater than zero, in seconds.
Use <em>data</em> followed by a number, greater than zero, of kilobytes to
change the default data channel renegotiation threshhold. The <em>timeout</em>
parameter, followed by a positive number of seconds, is used to change the
length of time given to a client to complete a requested renegotiation, after
which the SSL session will be shutdown. By default, <code>mod_tls</code>
will <b>require</b> that the client comply with the requested renegotiation
within the <code>TLSRenegotiate</code> timeout. If, however, the client is
unwilling or unable to do so, and the daemon needs to support these clients,
set <em>required</em> to <i>off</i>. Doing so will cause renegotiations to
be requested, but not required.
<p>
By default, <code>mod_tls</code> will perform renegotiations if supported, on
the control channel after 4 hours, and on the data channel after one gigabyte
of transferred data. The default timeout for a renegotiation is 30 seconds.
<p>
Use <em>none</em> to disable all renegotiation requirements.
<p>
Examples:
<pre>
# Change renegotiations to occur on control channels after 1 hour
TLSRenegotiate ctrl 3600
# Change renegotiations to occur on data channels after 500 MB
TLSRenegotiate data 512000
# Change renegotiations so that they are not required, only requested
TLSRenegotiate required off
# Change only the timeout for renegotiations to be 5 minutes
TLSRenegotiate timeout 300
# Change all of the above renegotiation threshholds using one directive
TLSRenegotiate ctrl 3600 data 512000 required off timeout 300
# To disable renegotiations entirely
TLSRenegotiate none
</pre>
<p>
<hr>
<h2><a name="TLSRequired">TLSRequired</a></h2>
<strong>Syntax:</strong> TLSRequired <em>on|off|ctrl|[!]data|auth|auth+[!]data</em><br>
<strong>Default:</strong> off<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSRequired</code> directive is used to define a basic security
policy, one that dictates whether the control channel, or data channel, or
both, of an FTP session must occur over SSL/TLS.
<p>
The <em>on</em> parameter enables SSL/TLS requirements on both control and
data channels; <em>off</em> disables the requirements on both channels.
Use <em>ctrl</em> and <em>data</em> to require SSL/TLS on either channel
individually.
<p>
Example:
<pre>
# Require SSL/TLS on the control channel, so that passwords are not sent
# in the clear.
TLSRequired ctrl
# Require SSL/TLS on both channels.
TLSRequired on
</pre>
The <em>auth</em> parameter requires that SSL/TLS be used on the control
channel, but only for authentication. To use this setting <i>and</i>
require SSL/TLS for data transfers, use the <em>auth+data</em> parameter,
<i>e.g.</i>:
<pre>
# Allow the client to use the CCC command to remove SSL/TLS from the
# control channel, but only after authentication has been performed.
# Still enforce the policy of using SSL/TLS for data transfers.
#
# Note that if we did not need to protect data transfers, we would
# set 'TLSRequired auth' instead of using 'TLSRequired auth+data'.
TLSRequired auth+data
</pre>
This <em>auth+data</em> parameter allows a very specific security policy:
authentication via the <code>USER</code>/<code>PASS</code> commands
<b>must</b> be protected via SSL/TLS, as must the data channel, but after
authenticating, the client can request that protection be removed from the
control channel. This policy allows clients to use the <code>CCC</code>
(<b>C</b>lear <b>C</b>ommand <b>C</b>hannel) command, which in turn enables
SSL/TLS protected data transfers that are operate better with firewalls that
monitor the FTP control channel.
<p>
It is <i>also</i> possible to configure a policy which <i>rejects</i> use
of SSL/TLS for protecting the data channel. Some sites may wish to use
such a policy in order to protect the control channels of their clients, but
to prevent the data transfers from consuming too much CPU. The
<code>TLSRequired</code> directive can be set such that an FTPS client
requesting protection of the data channel, using the <code>PROT</code> command,
will have that command refused. To configure such a policy, use one of
the following:
<pre>
# If the client wishes to protect the control channel, allow it; but reject
# any attempt to protect the data channel
TLSRequired !data
# <b>Require</b> protection on the control channel, but reject protection of the
# data channel
TLSRequired ctrl+!data
# <b>Require</b> protection on the control channel for <i>authentication</i> (but not
# after), and reject protection of the data channel
TLSRequired auth+!data
</pre>
<p>
<hr>
<h2><a name="TLSRSACertificateFile">TLSRSACertificateFile</a></h2>
<strong>Syntax:</strong> TLSRSACertificateFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSRSACertificateFile</code> directive points to the PEM-encoded
file containing the RSA certificate file for the server and optionally also
the corresponding RSA private key file.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted. Alternatively, the <code>TLSPassPhraseProvider</code>
directive can be used to supply a source for that passphrase.
<p>
Example:
<pre>
TLSRSACertificateFile /etc/ftpd/server-rsa-cert.pem
</pre>
<p>
<hr>
<h2><a name="TLSRSACertificateKeyFile">TLSRSACertificateKeyFile</a></h2>
<strong>Syntax:</strong> TLSRSACertificateKeyFile <em>file</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSRSACertificateKeyFile</code> directive points to the PEM-encoded
private key file for the server. If the private key is not combined with the
certificate in the <code>TLSRSACertificateFile</code>, use this additional
directive to point to the file with the standalone private key. When
<code>TLSRSACertificateFile</code> is used and the file contains both the
certificate and the private key, this directive need not be used. However,
this practice is strongly discouraged. Instead we recommend you to separate
the certificate and the private key.
<p>
If the contained private key is encrypted, the administrator will be
prompted for the passphrase when the daemon starts up, and when the daemon
is restarted.
<p>
Example:
<pre>
TLSRSACertificateKeyFile /etc/ftpd/server-rsa-key.pem
</pre>
<p>
<hr>
<h2><a name="TLSServerCipherPreference">TLSServerCipherPreference</a></h2>
<strong>Syntax:</strong> TLSServerCipherPreference <em>on|off</em><br>
<strong>Default:</strong> Off<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc1 and later
<p>
When choosing a cipher during an SSLv3 or TLSv1 handshake, normally the
<i>client's</i> ciphersuite preference is used. If the
<code>TLSServerCipherPreference</code> directive is enabled, then the
<i>server's</i> ciphersuite preference will be used instead.
<p>
For example:
<pre>
TLSServerCipherPreference on
</pre>
<p>
<hr>
<h2><a name="TLSSessionCache">TLSSessionCache</a></h2>
<strong>Syntax:</strong> TLSSessionCache <em>"off"|type:/info [timeout]</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config<br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.3rc1 and later
<p>
The <code>TLSSessionCache</code> directive configures an external SSL session
cache, which can be used for storing and shared SSL sessions across multiple
processes. An external SSL session cache is an optional facility which speeds
up parallel FTPS session connections.
<p>
Modern FTP clients often create multiple simultaneous connections to an FTP
server, for downloading different chunks of data in parallel. Each FTP
connection will be handled by a different server process, and each one
will be required to perform a full SSL/TLS handshake. By using an
external SSL session cache, a cached SSL session can be "resumed" by the
client, which avoids the expensive portions of the handshake. FTPS clients
which cache the SSL session locally can also attempt to resume that cached
session at a later date; if the server still has that same session cached,
the FTPS client can again avoid the expensive portions of the handshake and
resume its previous SSL session.
<p>
If the <code>TLSSessionCache</code> directive is <i>not</i> used, then
OpenSSL's default internal SSL session caching will be used. Thus multiple
SSL sessions to the same server process (<i>e.g.</i> for FTP data transfers)
will benefit from the speedup, but parallel simultaneous FTP connections from
the same FTPS client will each need to perform the full SSL/TLS handshake.
By default, OpenSSL caches SSL sessions for 300 seconds (5 minutes). If
your FTP sessions last longer than this (<i>e.g.</i> for downloading large
files), you may need to configure a longer cache lifetime using:
<pre>
# Configure OpenSSL's internal caching to be 1800 seconds (30 minutes)
TLSSessionCache internal: 1800
</pre>
<p>
The <em>type</em> and <em>info</em> parameters all depend on the module
implementing the external SSL session cache being configured. For example,
for using a shared memory external SSL session cache, see the
<a href="mod_tls_shmcache.html"><code>mod_tls_shmcache</code></a> documentation.
<p>
The optional <em>timeout</em> parameters sets the time-to-live, in seconds, for
the SSL session datal stored in the external SSL session cache. It can be set
as low as 15 for testing, but should be set to higher values like 600 in real
life. The default timeout is 1800 seconds (30 minutes).
<p>
Use of SSL session caching can be disabled entirely by using:
<pre>
TLSSessionCache off
</pre>
<p>
<hr>
<h2><a name="TLSTimeoutHandshake">TLSTimeoutHandshake</a></h2>
<strong>Syntax:</strong> TLSTimeoutHandshake <em>seconds</em><br>
<strong>Default:</strong> 300<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.9rc1 and later
<p>
The <code>TLSTimeoutHandshake</code> directive configures the maximum number
of seconds for <code>mod_tls</code> to accept an SSL/TLS handshake. If set to
zero, <code>mod_tls</code> will wait forever for a handshake to complete. The
default is 300 seconds (five minutes).
<p>
<hr>
<h2><a name="TLSUserName">TLSUserName</a></h2>
<strong>Syntax:</strong> TLSUserName <em>attribute</em><br>
<strong>Default:</strong> off<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc2 and later
<p>
The <code>TLSUserName</code> directive configures which <em>attribute</em>
of a client certificate to match against the name provided by the FTPS client
in its <code>USER</code> command. If the certificate <em>attribute</em>
value matches the <code>USER</code> name, the user is considered to be
authenticated <b>without requiring that password be sent over the network</b>.
<p>
The <em>attribute</em> can either be "CommonName" (to match the CN of the
client certificate to the requested <code>USER</code> name),
"EmailSubjAltName" (to match <b>any</b> Email Subject Alternative Names (SANs)
to the requested <code>USER</code> name), or a custom OID.
<p>
Examples:
<pre>
# Match the CN
TLSUserName CommonName
# Match any Email SANs
TLSUserName EmailSubjAltName
# Match specific (custom) OID
TLSUserName 1.2.3.4.5
</pre>
<p>
Note that for the <code>TLSUserName</code> directive to be effective,
<code>mod_tls</code> has to be configured to request that clients provide
certificates, <i>i.e.</i>:
<pre>
# Verify clients
TLSVerifyClient on
# and possibly verify the user based on the client certs
TLSUserName CommonName
</pre>
<p>
See also: <a href="#TLSVerifyClient"><code>TLSVerifyClient</code></a>
<p>
<hr>
<h2><a name="TLSVerifyClient">TLSVerifyClient</a></h2>
<strong>Syntax:</strong> TLSVerifyClient <em>on|off</em><br>
<strong>Default:</strong> off<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSVerifyClient</code> directive configures how <code>mod_tls</code>
handles certificates presented by clients. If <em>off</em>, the module
will accept the certificate and establish an SSL/TLS session, but will not
verify the certificate. If <em>on</em>, the module will verify a client's
certificate and, furthermore, will fail all SSL handshake attempts <b>unless</b>
the client presents a certificate when the server requests one. Note that the
server can be configured to <i>not</i> request a client certificate via
the <code>TLSOptions</code> directive's "NoCertRequest" parameter.
<p>
See also: <a href="#TLSOptions"><code>TLSOptions</code></a>
<p>
<hr>
<h2><a name="TLSVerifyDepth">TLSVerifyDepth</a></h2>
<strong>Syntax:</strong> TLSVerifyDepth <em>depth</em><br>
<strong>Default:</strong> 9<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.2.7rc1 and later
<p>
The <code>TLSVerifyDepth</code> directive sets how deeply <code>mod_tls</code>
should verify before deciding that the client does not have a valid
certificate. The depth actually is the maximum number of intermediate
certificate issuers, <i>i.e.</i> the number of CA certificates which are
allowed to be followed while verifying the client certificate. A depth of 0
means that only self-signed client certificates are accepted, a depth of 1
means the client certificate can be self-signed or has to be signed by a CA
which is directly known to the server (<i>i.e.</i> the CA's certificate is
under <code>TLSCACertificatePath</code>), etc.
<p>
Example:
<pre>
TLSVerifyDepth 10
</pre>
<p>
<hr>
<h2><a name="TLSVerifyOrder">TLSVerifyOrder</a></h2>
<strong>Syntax:</strong> TLSVerifyOrder <em>crl|ocsp</em><br>
<strong>Default:</strong> crl<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.2rc1 and later
<p>
The <code>TLSVerifyOrder</code> directive configures how the
<code>mod_tls</code> will verify the certificates presented by clients, if
at all. Unless <code>TLSVerifyClient</code> is <em>on</em>, the
<code>TLSVerifyOrder</code> directive is not needed.
<p>
By default, the <code>mod_tls</code> module will include any CRLs (Certificate
Revocation List) that may have been configured via the
<code>TLSCARevocationFile</code> and/or <code>TLSCARevocationPath</code>
directives. This default behavior is the equivalent of configuring the
<code>TLSVerifyOrder</code> to use CRLs, <i>e.g.</i>:
<pre>
TLSVerifyOrder crl
</pre>
<p>
Another way of checking the validity of the client certificate is to use
the Online Certificate Status Protocol (OCSP), defined in
<a href="http://www.faqs.org/rfcs/rfc2560.html">RFC 2560</a>. To configure
the <code>mod_tls</code> module to use OCSP when verifying, use:
<pre>
TLSVerifyOrder ocsp
</pre>
Note that at is possible for <code>mod_tls</code> to use both CRLs <i>and</i>
OCSP when verifying certificates. Simply use <code>TLSVerifyOrder</code>
to configure the order in which <code>mod_tls</code> should use the various
verification mechanisms:
<pre>
TLSVerifyOrder ocsp crl
</pre>
Verification ends when a mechanism can successfully verify the certificate.
<p>
See also: <a href="#TLSCARevocationFile"><code>TLSCARevocationFile</code></a>,
<a href="#TLSCARevocationPath"><code>TLSCARevocationPath</code></a>
<p>
<hr>
<h2><a name="TLSVerifyServer">TLSVerifyServer</a></h2>
<strong>Syntax:</strong> TLSVerifyServer <em>on|off|NoReverseDNS</em><br>
<strong>Default:</strong> on<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_tls<br>
<strong>Compatibility:</strong> 1.3.5rc4 and later
<p>
The <code>TLSVerifyServer</code> directive configures how <code>mod_tls</code>
handles certificates presented by <em>other servers</em>, during a secure
site-to-site (<i>a.k.a.</i> "secure FXP") transfer. If <em>off</em>, the
module will accept the certificate and establish an SSL/TLS session, but will
<b>not</b> verify the certificate. If <em>on</em>, the module will verify a
server's certificate and, furthermore, will fail all SSL handshake attempts
<b>unless</b> the server presents a valid certificate.
<p>
The <em>NoReverseDNS</em> parameter tells <code>mod_tls</code> to validate
the server's certificate, <b>but</b> to only validate it based on IP address,
rather than using DNS names (for <i>e.g.</i> CommonName (CN) and DNS
SubjectAltName (SAN) checks). The recommended certificate validation
techniques use DNS names, so using <em>NoReverseDNS</em> performs less
strict validations. Unfortunately, in most secure site-to-site transfers,
this setting may be required since FTP site-to-site transfers send IP
addresses, not DNS names, in the command which establish the data transfer.
<p>
See also: <a href="#TLSVerifyClient"><code>TLSVerifyClient</code></a>,
<a href="#TLSVerifyDepth"><code>TLSVerifyDepth</code></a>
<p>
<hr>
<h2>Control Actions</h2>
<p>
<hr>
<h3><a name="tls_sesscache_clear"><code>tls sesscache clear</code></a></h3>
<strong>Syntax:</strong> ftpdctl tls sesscache clear<br>
<strong>Purpose:</strong> Clears all cached sessions from the SSL session cache<br>
<p>
The <code>tls sesscache clear</code> action is used to clear all cached
sessions, whether they have expired or not, from the configured external
SSL session cache. For example:
<pre>
# ftpdctl tls sesscache clear
ftpdctl: tls sesscache: cleared 1 session from 'shm' session cache
</pre>
<p>
See also: <a href="#TLSSessionCache"><code>TLSSessionCache</code></a>
<p>
<hr>
<h3><a name="tls_sesscache_info"><code>tls sesscache info</code></a></h3>
<strong>Syntax:</strong> ftpdctl tls sesscache info <em>[-v]</em><br>
<strong>Purpose:</strong> Displays status of session cache<br>
<p>
The <code>tls sesscache info</code> action is used to display information
about the configured external SSL session cache. If the optional <em>-v</em>
command-line option is used, then information about each cached session
will also be displayed.
<p>
For example:
<pre>
# ftpdctl tls sesscache info -v
ftpdctl: Shared memory (shm) SSL session cache provided by mod_tls_shmcache/0.1
ftpdctl:
ftpdctl: Shared memory segment ID: 589824
ftpdctl: Shared memory segment size: 1576960 bytes
ftpdctl: Shared memory cache created on: Mon Mar 9 21:18:05 2009
ftpdctl: Shared memory attach count: 1
ftpdctl:
ftpdctl: Max session cache size: 153
ftpdctl: Current session cache size: 1
ftpdctl:
ftpdctl: Cache lifetime hits: 0
ftpdctl: Cache lifetime misses: 0
ftpdctl:
ftpdctl: Cache lifetime sessions stored: 1
ftpdctl: Cache lifetime sessions deleted: 0
ftpdctl: Cache lifetime sessions expired: 0
ftpdctl:
ftpdctl: Cache lifetime errors handling sessions in cache: 0
ftpdctl: Cache lifetime sessions exceeding max entry size: 0
ftpdctl:
ftpdctl: Cached sessions:
ftpdctl: -----BEGIN SSL SESSION PARAMETERS-----
ftpdctl: Session ID: A9BB647E236BAB0EF128FE9EAD2ABEC6F8E65C9EB8F050A07D1F0F66EC3019DC
ftpdctl: Session ID Context: 00000000
ftpdctl: Protocol: TLSv1
ftpdctl: Started: Mon Mar 9 21:19:20 2009
ftpdctl: Expires: Tue Mar 10 21:19:20 2009 (86400 secs)
ftpdctl: -----END SSL SESSION PARAMETERS-----
</pre>
<p>
See also: <a href="#TLSSessionCache"><code>TLSSessionCache</code></a>
<p>
<hr>
<h3><a name="tls_sesscache_remove"><code>tls sesscache remove</code></a></h3>
<strong>Syntax:</strong> ftpdctl tls sesscache remove<br>
<strong>Purpose:</strong> Removes the external SSL session cache<br>
<p>
The <code>tls sesscache remove</code> action is used to remove the
external SSL session cache entirely. Depending on the actual module providing
the session cache, this may or may not be implemented.
<p>
For example:
<pre>
# ftpdctl tls sesscache remove
ftpdctl: tls sesscache: removed 'shm' session cache
</pre>
<p>
See also: <a href="#TLSSessionCache"><code>TLSSessionCache</code></a>
<p>
<hr>
<h2><a name="Usage">Usage</a></h2>
Much of the documentation for Apache's <code>mod_ssl</code>, concerning
certificates, OpenSSL usage, <i>etc</i> applies to this module as well:
<pre>
<a href="http://www.modssl.org/docs/2.7/">http://www.modssl.org/docs/2.7/</a>
</pre>
The OpenSSL documentation, and its
<a href="http://www.openssl.org/support/faq.cgi">FAQ</a>, are recommended as
well:
<pre>
<a href="http://www.openssl.org/docs/">http://www.openssl.org/docs/</a>
</pre>
<p>
There is also a script, <code>cert-tool</code>, that can help in the creation
of certificates. See <code>cert-tool --help</code> for usage information:
<pre>
<a href="http://www.castaglia.org/openssl/contrib/cert-tool">http://www.castaglia.org/openssl/contrib/cert-tool</a>
</pre>
<p>
A copy of the Draft describing FTP over SSL/TLS is included with the source
code for this module.
<p>
<hr>
<h2><a name="Installation">Installation</a></h2>
The <code>mod_tls</code> module is distributed with ProFTPD. Simply follow
the normal steps for using third-party modules in proftpd:
<pre>
./configure --with-modules=mod_tls
make
make install
</pre>
Alternatively, <code>mod_tls</code> can be built as a DSO module:
<pre>
./configure --enable-dso --with-shared=mod_tls ...
</pre>
Then follow the usual steps:
<pre>
make
make install
</pre>
<p>
You may need to specify the location of the OpenSSL header and library files
in your <code>configure</i> command, <i>e.g.</i>:
<pre>
./configure --with-modules=mod_tls \
--with-includes=/usr/local/openssl \
--with-libraries=/usr/local/openssl
</pre>
<p>
<hr><br>
Author: <i>$Author: castaglia $</i><br>
Last Updated: <i>$Date: 2013-12-09 23:15:16 $</i><br>
<hr>
<font size=2><b><i>
© Copyright 2002-2013 TJ Saunders<br>
All Rights Reserved<br>
</i></b></font>
<hr><br>
</body>
</html>
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