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<h2><b>ProFTPD module <code>mod_wrap2</code></b></h2>
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<hr>
The <code>mod_wrap2</code> package allows the <code>proftpd</code> daemon to
provide <code>tcpwrapper</code>-like access control rules while running
in standalone mode. It also allows for those access rules to be stored
in various formats, such as files (<i>e.g.</i> <code>/etc/hosts.allow</code>
and <code>/etc/hosts.deny</code>) or in SQL tables. <b>Note</b> that the
<code>mod_wrap2</code> module does <b>not</b> require or use the
standard tcpwrappers <code>libwrap</code> library, and instead implements
the same functionality internally (in order to support SQL-based access rules).
Please read the <a href="#Usage">usage</a> documentation for more details.
<p>
This module is contained in <code>mod_wrap2.c</code>,
<code>mod_wrap2.h</code>, and in the submodules source files, for
ProFTPD 1.3.<i>x</i>. These modules are not enabled by default. Installation
<a href="#Installation">notes</a> follow the directive documentation.
<p>
The most current version of <code>mod_wrap2</code>'s submodules supports
storage of access table information in various formats:
<a name="submodules"></a>
<ul>
<li><a href="mod_wrap2_file.html"><code>mod_wrap2_file</code></a> for file-based access tables<br>
<li><a href="mod_wrap2_sql.html"><code>mod_wrap2_sql</code></a> for SQL-based access tables<br>
</ul>
<p>
The most current version of <code>mod_wrap2</code> is distributed with the
ProFTPD source code.
<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>
Many, many thanks to Wietse Venema for writing the <code>tcpwrappers</code>
package and its <code>libwrap</code> library, from which this module drew
much of its code.
<p>
<i>2002-12-12</i>: Thanks to Steve Grubb for pointing out a few cases where
interrupted functions were not being properly handled, and for reviewing
the module code.
<h2>Directives</h2>
<ul>
<li><a href="#WrapAllowMsg">WrapAllowMsg</a>
<li><a href="#WrapDenyMsg">WrapDenyMsg</a>
<li><a href="#WrapEngine">WrapEngine</a>
<li><a href="#WrapGroupTables">WrapGroupTables</a>
<li><a href="#WrapLog">WrapLog</a>
<li><a href="#WrapServiceName">WrapServiceName</a>
<li><a href="#WrapTables">WrapTables</a>
<li><a href="#WrapUserTables">WrapUserTables</a>
</ul>
<hr>
<h2><a name="WrapAllowMsg">WrapAllowMsg</a></h2>
<strong>Syntax:</strong> WrapAllowMsg <em>mesg</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost</code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>WrapAllowMsg</code> directive configures a message that will be
added to <code>proftpd</code>'s response to the connecting client when that
client is allowed by <code>mod_wrap2</code>'s access check. In the
<em>mesg</em> parameter, the magic cookie '%u' is replaced with the username
specified by the client during login.
<p>
Example:
<pre>
WrapAllowMsg "User '%u' allowed by access rules"
</pre>
<p>
<hr>
<h2><a name="WrapDenyMsg">WrapDenyMsg</a></h2>
<strong>Syntax:</strong> WrapDenyMsg <em>mesg</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost</code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>WrapDenyMsg</code> directive configures a message that will be
sent to the connecting client when that client is denied by
<code>mod_wrap2</code>'s access check, and disconnected. In the <em>mesg</em>
parameter, the magic cookie '%u' is replaced with the username specified by
the client during login.
<p>
Example:
<pre>
WrapDenyMsg "User '%u' denied by access rules"
</pre>
<p>
<hr>
<h2><a name="WrapEngine">WrapEngine</a></h2>
<strong>Syntax:</strong> WrapEngine <em>on|off</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later</a>
<p>
The <code>WrapEngine</code> directive enables or disables the module's runtime
access control engine. If it is set to <em>off</em> this module does no runtime
processing at all. Use this directive to disable the module instead of
commenting out all <code>mod_wrap2</code> directives.
<p>
<hr>
<h2><a name="WrapGroupTables">WrapGroupTables</a></h2>
<strong>Syntax:</strong> WrapGroupTables <em>group-AND-expression source-type:allow-source-info source-type:deny-source-info [source-type:options-source-info]</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost</code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>WrapGroupTables</code> directive configures the information necessary
for <code>mod_wrap2</code> to locate and use the tables containing the access
rules for specific groups.
<p>
The <em>group-AND-expression</em> parameter is a logical AND expression, which
means that the connecting user must be a member of <b>all</b> the groups
listed for this directive to apply. Group names may be negated with a
<code>!</code> prefix.
<p>
The next two parameters specify two tables, an allow and a deny table, each of
which contain the IP addresses, networks or host/network masks to be allowed or
denied.
<p>
Please consult the relevant <a href="#submodule">submodule</a> documentation
for details on that module's syntax for specifying tables. The service name
for which <code>mod_wrap2</code> will look in the indicated access tables is
"proftpd" by default; this can be configured via the
<a href="#WrapServiceName><code>WrapServiceName</code></a> directive.
<p>
See also:
<a href="#WrapServiceName">WrapServiceName</a>,
<a href="#WrapTables">WrapTables</a>,
<a href="#WrapUserTables">WrapUserTables</a>
<p>
<hr>
<h2><a name="WrapLog">WrapLog</a></h2>
<strong>Syntax:</strong> WrapLog <em>file|"none"</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later</a>
<p>
The <code>WrapLog</code> directive is used to a specify a log file for
<code>mod_wrap2</code> reporting, and can be done a per-server basis.
The <em>file</em> parameter must be the full path to the file to use for
logging. Note that this path must <b>not</b> be to a world-writeable
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>
If <em>file</em> is "none", no logging will be done at all; this
setting can be used to override a <code>WrapLog</code> setting inherited from
a <code><Global></code> context.
<p>
<hr>
<h2><a name="WrapServiceName">WrapServiceName</a></h2>
<strong>Syntax:</strong> WrapServiceName <em>name</em><br>
<strong>Default:</strong> <code>WrapServiceName proftpd</code><br>
<strong>Context:</strong> server config, <code><VirtualHost></code>, <code><Global></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
<code>WrapServiceName</code> is used to configure the name of the service under
which <code>mod_wrap2</code> will check the allow/deny tables. By default, this
is the name of the program started, <em>i.e.</em> "proftpd". However,
some administrators may want to use a different, more generic service name,
such as "ftpd"; use this directive for such needs. The lookup
using the configured <em>name</em> is <b>case-sensitive</b>.
<p>
<hr>
<h2><a name="WrapTables">WrapTables</a></h2>
<strong>Syntax:</strong> WrapTables <em>source-type:allow-source-info source-info:deny-source-info</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost</code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>WrapTables</code> directive configures the information necessary
for <code>mod_wrap2</code> to locate and use the tables containing the access
rules for all clients.
<p>
The two parameters specify two tables, an allow and a deny table, each of which
contain the IP addresses, networks or host/network masks to be allowed or
denied.
<p>
Please consult the relevant <a href="#submodule">submodule</a> documentation
for details on that module's syntax for specifying tables. The service name
for which <code>mod_wrap2</code> will look in the indicated access tables is
"proftpd" by default; this can be configured via the
<a href="#WrapServiceName><code>WrapServiceName</code></a> directive.
<p>
See also:
<a href="#WrapGroupTables">WrapGroupTables</a>,
<a href="#WrapServiceName">WrapServiceName</a>,
<a href="#WrapUserTables">WrapUserTables</a>
<p>
<hr>
<h2><a name="WrapUserTables">WrapUserTables</a></h2>
<strong>Syntax:</strong> WrapUserTables <em>user-OR-expression source-type:allow-source-info source-type:deny-source-info [source-type:option-source-info]</em><br>
<strong>Default:</strong> None<br>
<strong>Context:</strong> server config, <code><VirtualHost</code>, <code><Global></code>, <code><Anonymous></code><br>
<strong>Module:</strong> mod_wrap2<br>
<strong>Compatibility:</strong> 1.3.1rc1 and later
<p>
The <code>WrapUserTables</code> directive configures the information necessary
for <code>mod_wrap2</code> to locate and use the tables containing the access
rules for specific users.
<p>
The <em>user-OR-expression</em> parameter is a logical OR expression, which
means that the connecting user can be <b>any</b> the users listed for this
directive to apply. User names may be negated with a <code>!</code> prefix.
<p>
The next two parameters specify two tables, an allow and a deny table, each of
which contain the IP addresses, networks or host/network masks to be allowed or
denied.
<p>
Please consult the relevant <a href="#submodule">submodule</a> documentation
for details on that module's syntax for specifying tables. The service name
for which <code>mod_wrap2</code> will look in the indicated access tables is
"proftpd" by default; this can be configured via the
<a href="#WrapServiceName><code>WrapServiceName</code></a> directive.
<p>
See also:
<a href="#WrapGroupTables">WrapGroupTables</a>,
<a href="#WrapServiceName">WrapServiceName</a>,
<a href="#WrapTables">WrapTables</a>
<p>
<hr><br>
<h2><a name="Usage">Usage</a></h2>
To use <code>mod_wrap2</code>'s functionality, you must first define the tables
that together contain the access rules. Access rules are composed of
<b>daemon lists</b>, <b>client lists</b>, and optional <b>options lists</b>.
<b>daemon lists</b> are used so that the access rules can be configured for
mulitple daemons; <code>mod_wrap2</code> ignores all daemons except that
configured for <code>proftpd</code>. <b>client lists</b> are the heart of
the access rules, specifying the host names, IP addresses, <i>etc</i> to
be allowed or denied. The handling of <b>options lists</b> is done only if
<code>mod_wrap2</code> is configured with the
<code>--enable-wrapper-options</b> option.
<p>
There is a built-in precedence to the <code>WrapUserTables</code>,
<code>WrapGroupTables</code>, and <code>WrapTables</code> directives, if all
are used. <code>mod_wrap2</code> will look for applicable
<code>WrapUserTables</code> for the connecting user first. If no applicable
<code>WrapUserTables</code> are found, <code>mod_wrap2</code> will search for
<code>WrapGroupTables</code> which pertain to the connecting user. If not
found, <code>mod_wrap2</code> will then look for the server-wide
<code>WrapTables</code> directive. This allows for access control to be set
on a per-server basis, and allow for per-user or per-group access control
to be handled without interfering with the overall server access rules.
<p>
When checking the tables, <code>mod_wrap2</code> always checks the allow
table first. If the client has been explicitly allowed by the rules in
that table, processing stops and <code>mod_wrap2</code> allows the client
to continue the session. If not explicitly allowed, <code>mod_wrap2</code>
will then check the deny table's access rules. If the client has been
explicity denied by rules in that table, <code>mod_wrap2</code> will
disconnect the client. By default, if neither explicitly allowed or
explicitly denied, <code>mod_wrap2</code> will allow the client to continue.
<p><a name="#builtin"></a>
In addition to the various formats supported by the
<a href="#submodules">submodules</a>, there is a special source type:
"builtin". This is used in the situations where the administrator
wishes to configure "mostly closed" access rules, the most common
situation. For example, if all clients are to be denied by
<code>mod_wrap2</code> by default, unless that client is granted access via an
allow table entry, then the administrator can use:
<pre>
builtin:all
</pre>
as the deny table parameter (<i>e.g.</i> in a <code>WrapUserTables</code>,
<code>WrapGroupTables</code>, or <code>WrapTables</code> directive), rather
than configuring a static deny table that always says ALL.
<p>
<h3><a name="AccessRules">Access Rules</a></h3>
When checking access rules, the check terminates when the first match is
found. A <b>client list</b> is a list of one or more host names, host
addresses, patterns or wildcards (see below) that will be matched against the
client host name or address. The more complex <i>daemon@host</i> and
<i>user@host</i> forms are explained in the sections on server endpoint
patterns and on client username lookups, respectively. With the exception of
NIS/YP netgroup lookups, all access control checks are case insensitive.
<p>
<b>Patterns</b><br>
The access control language implements the following patterns:
<ul>
<li>A string that begins with a `.' character. A host name is matched if the
last components of its name match the specified pattern. For example, the
pattern <code>.castaglia.org</code> matches the host name
<code>golem.devlan.castaglia.org</code>.
<p>
<li>A string that ends with a `.' character. A host address is matched if its
first numeric fields match the given string. For example, the pattern
<code>131.155.</code> matches the address of (almost) every host on the
Eindhoven University network (<code>131.155.<i>x</i>.<i>x</i></code>).
<p>
<li>A string that begins with an `@' character is treated as an NIS (formerly
YP) netgroup name. A host name is matched if it is a host member of the
specified netgroup. Netgroup matches are not supported for client user
names. <i>Note</i> that <code>mod_wrap2</code> must be configured for NIS
support for netgroup lookups to occur.
<p>
<li>An expression of the form <i>n.n.n.n/m.m.m.m</i> is interpreted as a
<code>net/mask</code> pair. An IPv4 address is matched if the
<code>net</code> portion is equal to the bitwise AND of the address and the
<code>mask</code> portion. For example, the <code>net/mask</code> pattern
<code>131.155.72.0/255.255.254.0</code> matches every address in the range
<code>131.155.72.0</code> through <code>131.155.73.255</code>.
<p>
<li>Wildcards `*' and `?' can be used to match hostnames or IP addresses.
This method of matching cannot be used in conjunction with
<code>net/mask</code> matching, hostname matching beginning with `.' or
IP address matching ending with `.'.
</ul>
<p>
<b>Wildcards</b><br>
The access control language supports explicit wildcards:
<ul>
<li>ALL<br>
The universal wildcard, always matches.
<p>
<li>LOCAL<br>
Matches any host whose name does not contain a dot character.
<p>
<li>UNKNOWN<br>
Matches any user whose name is unknown, and matches any host whose name or
address are unknown. This pattern should be used with care: host names may
be unavailable due to temporary name server problems.
<p>
<li>KNOWN<br>
Matches any user whose name is known, and matches any host whose name and
address are known. This pattern should be used with care: host names may be
unavailable due to temporary name server problems.
<p>
<li>PARANOID<br>
Matches any host whose name does not match its address, before looking
at the access control tables.
</ul>
<p>
<b>Operators</b><br>
<ul>
<li>EXCEPT<br>
Intended use is of the form:
<pre>
<em>list1</em> EXCEPT <em>list2</em>
</pre>
This construct matches anything that matches <em>list1</em> unless it
matches <em>list2</em>. The EXCEPT operator can be used in <b>daemon
lists</b> and <b>client lists</b>. The EXCEPT operator can be nested: if
the control language would permit the use of parentheses:
<pre>
a EXCEPT b EXCEPT c
</pre>
would parse as
<pre>
(a EXCEPT (b EXCEPT c))
</pre>
</ul>
<p>
<b>Server Endpoint Patterns</b><br>
In order to distinguish clients by the network address that they connect to,
use patterns of the form:
<pre>
<i>process-name</i>@<i>host-pattern</i> : <i>client-list</i> ...
</pre>
Patterns like these can be used when the machine has different Internet
addresses with different Internet hostnames. Service providers can use this
facility to offer FTP, GOPHER or WWW archives with Internet names that may even
belong to different organizations. Some systems can have more than one
Internet address on one physical interface.
<p>
The <i>host-pattern</i> obeys the same syntax rules as host names and addresses
in <b>client lists</b>.
<p>
<b>Client Username Lookup</b><br>
When the client host supports the RFC 931 protocol, the <code>proftpd</code>
daemon can retrieve additional information about the owner of a connection.
Client username information, when available (<i>i.e.</i> when
<code>IdentLookups</code> are not disabled), is logged together with the client
host name, and can be used to match patterns like:
<pre>
<i>daemon-list</i> : ... <i>user-pattern</i>@<i>host-pattern</i> ...
</pre>
<p>
A <i>user-pattern</i> has the same syntax as a daemon pattern, so the same
wildcards apply (netgroup membership is not supported). One should not get
carried away with username lookups, though:
<ul>
<li>The client username information cannot be trusted when it is needed
most, <i>i.e.</i> when the client system has been compromised. In
general, ALL and (UN)KNOWN are the only user name patterns that make sense.
<p>
<li>Username lookups are possible only when the client host runs a suitable
daemon; in all other cases the result is "unknown".
</ul>
<p>
<h3><a name="AccessOptions">Access Options</a></h3>
This section describes optional <b>options list</b> portion the access control
language described above. The <b>options list</b> syntax uses the following
format:
<pre>
<i>opt1</i> : <i>opt2</i> ...
</pre>
Any `:' characters within options should be protected with a backslash.
<p>
An option is of the form <code>"keyword"</code> or
<code>"keyword value"</code>. Options are processed in the
specified order. For the sake of backwards compatibility with earlier
versions, a `=' is permitted between keyword and value.
<ul>
<li>ALLOW<br>
Grant service. This option must appear at the end of a rule.
</li>
<p>
<li>DENY<br>
Deny service. This option must appear at the end of a rule.
</li>
</ul>
<p>
The allow and deny keywords make it possible to keep all access control
rules within a single file, for example in the <code>hosts.allow</code>
file. To permit access from specific hosts only:
<pre>
ALL: .friendly.domain: ALLOW
ALL: ALL: DENY
</pre>
To permit access from all hosts except a few trouble makers:
<pre>
ALL: .bad.domain: DENY
ALL: ALL: ALLOW
</pre>
Notice the leading dot on the domain name patterns.
<ul>
<p>
<li>nice <em>[number]</em><br>
Change the nice value of the process (default 10). Specify a positive
value to spend more CPU resources on other processes.
<p>
<li>setenv <em>name=value</em><br>
Place a <code>name=value</code> pair into the process environment. The
value may contain whitespace (but leading and trailing blanks are stripped
off).
</ul>
<p>
<b>Diagnostics</b><br>
When a syntax error is found in an options list, the error is reported in the
<code>WrapLog</code> and the access option will be ignored.
<p>
<hr><br>
<h2><a name="Installation">Installation</a></h2>
After unpacking the latest proftpd-1.3.<i>x</i> source code, follow the usual
steps for using third-party modules in <code>proftpd</code>:
<pre>
./configure --with-modules=<em>wrap-modules</em>
make
make install
</pre>
where <em>wrap-modules</em> will depend on the types of access tables you wish
to support.
<p>
For file-based access tables, include the <code>mod_wrap2_file</code>
submodule, <i>e.g.</i>:
<pre>
mod_wrap2:mod_wrap2_file
</pre>
For SQL-based access tables, include the <code>mod_wrap2_sql</code>
submodule, <i>e.g.</i>:
<pre>
mod_wrap2:mod_wrap2_sql
</pre>
And, if you wish to support both file- and SQL-based access tables, use:
<pre>
mod_wrap2:mod_wrap2_file:mod_wrap2_sql
</pre>
Note that SQL tables require that a correct installation of <code>mod_sql</code>
(and any of its backend modules) also be used. Consult the <code>mod_sql</code>
documentation for installation instructions for that module.
<p>
<hr><br>
Author: <i>$Author: castaglia $</i><br>
Last Updated: <i>$Date: 2006/09/06 23:09:58 $</i><br>
<br><hr>
<font size=2><b><i>
© Copyright 2000-2006 TJ Saunders<br>
All Rights Reserved<br>
</i></b></font>
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