Index: privoxy-3.0.29-stable/jbsockets.c
===================================================================
--- privoxy-3.0.29-stable/jbsockets.c
+++ privoxy-3.0.29-stable/jbsockets.c	2020-11-29 09:15:29.355801127 +0100
@@ -233,7 +233,17 @@
    }
 
    memset((char *)&hints, 0, sizeof(hints));
-   hints.ai_family = AF_UNSPEC;
+   switch(csp->config->address_family_preference)
+   {
+      case ADDRESS_FAMILY_PREFERENCE_IPV4:
+         hints.ai_family = AF_INET;
+         break;
+      case ADDRESS_FAMILY_PREFERENCE_IPV6:
+         hints.ai_family = AF_INET6;
+         break;
+      default:
+         hints.ai_family = AF_UNSPEC;
+   }
    hints.ai_socktype = SOCK_STREAM;
    hints.ai_flags = AI_NUMERICSERV; /* avoid service look-up */
 #ifdef AI_ADDRCONFIG
Index: privoxy-3.0.29-stable/loadcfg.c
===================================================================
--- privoxy-3.0.29-stable/loadcfg.c
+++ privoxy-3.0.29-stable/loadcfg.c	2020-11-29 09:17:34.443048783 +0100
@@ -130,6 +130,7 @@
 #define hash_actions_file                1196306641U /* "actionsfile" */
 #define hash_accept_intercepted_requests 1513024973U /* "accept-intercepted-requests" */
 #define hash_admin_address               4112573064U /* "admin-address" */
+#define hash_address_family_preference   3725998957U /* "address-family-preference */
 #define hash_allow_cgi_request_crunching  258915987U /* "allow-cgi-request-crunching" */
 #define hash_buffer_limit                1881726070U /* "buffer-limit */
 #define hash_ca_cert_file                1622923720U /* "ca-cert-file" */
@@ -1154,6 +1155,31 @@
             break;
 
 /* *************************************************************************
+ * address-family-preference ipv4|IPv4|ipv6|IPv6|none
+ * *************************************************************************/
+         case hash_address_family_preference:
+            if (!strcmp(arg, "ipv4") || !strcmp(arg, "IPv4"))
+            {
+               config->address_family_preference = ADDRESS_FAMILY_PREFERENCE_IPV4;
+            }
+            else if (!strcmp(arg, "ipv6") || !strcmp(arg, "IPv6"))
+            {
+               config->address_family_preference = ADDRESS_FAMILY_PREFERENCE_IPV6;
+            }
+            else if (!strcmp(arg, "none"))
+            {
+               config->address_family_preference = ADDRESS_FAMILY_PREFERENCE_NONE;
+            }
+            else
+            {
+               log_error(LOG_LEVEL_FATAL,
+                  "Directive %s used with invalid argument '%s'. Use 'ipv6', 'ipv4', or 'none'.",
+                  cmd, arg);
+            }
+            break;
+
+
+/* *************************************************************************
  * forward url-pattern (.|http-proxy-host[:port])
  * *************************************************************************/
          case hash_forward:
Index: privoxy-3.0.29-stable/project.h
===================================================================
--- privoxy-3.0.29-stable/project.h
+++ privoxy-3.0.29-stable/project.h	2020-11-29 09:19:53.120359562 +0100
@@ -979,6 +979,17 @@
  */
 #define MAX_LISTENING_SOCKETS 10
 
+enum address_family_preference
+{
+   /** No preference, let the OS decide. */
+   ADDRESS_FAMILY_PREFERENCE_NONE = 0,
+   /** Ask the OS for IPv4 addresses only. */
+   ADDRESS_FAMILY_PREFERENCE_IPV4,
+   /** Ask the OS for IPv6 addresses only. */
+   ADDRESS_FAMILY_PREFERENCE_IPV6
+};
+
+
 struct ssl_attr {
 #ifdef FEATURE_HTTPS_INSPECTION_MBEDTLS
    mbedtls_connection_attr  mbedtls_attr; /* Mbed TLS attrs*/
@@ -1557,6 +1568,9 @@
    unsigned int default_server_timeout;
 #endif
 
+   /** Preference for the address family for outgoing connections. */
+   enum address_family_preference address_family_preference;
+
 #ifdef FEATURE_COMPRESSION
    int compression_level;
 #endif
Index: privoxy-3.0.29-stable/doc/source/p-config.sgml
===================================================================
--- privoxy-3.0.29-stable/doc/source/p-config.sgml
+++ privoxy-3.0.29-stable/doc/source/p-config.sgml	2020-11-29 09:21:24.470783855 +0100
@@ -3827,6 +3827,44 @@
 </variablelist>
 </sect3>
 
+<sect3 renderas="sect4" id="address-family-preference"><title>address-family-preference</title>
+<variablelist>
+ <varlistentry>
+  <term>Specifies:</term>
+  <listitem>
+   <para>
+    Whether a specific address family (IPv4 or IPv6) is preferred for outgoing connections.
+   </para>
+  </listitem>
+ </varlistentry>
+ <varlistentry>
+  <term>Type of value:</term>
+  <listitem>
+   <para>
+    <replaceable>none or ipv4 or ipv6</replaceable>
+   </para>
+  </listitem>
+ </varlistentry>
+ <varlistentry>
+  <term>Default value:</term>
+  <listitem>
+   <para>none</para>
+  </listitem>
+ </varlistentry>
+ <varlistentry>
+  <term>Notes:</term>
+  <listitem>
+   <para>
+     By default &my-app; performs generic DNS lookups, often preferring IPv6 in practice.
+     When this option is set to something other than none, addresses from the specified
+     family are requested from the OS.
+   </para>
+  </listitem>
+ </varlistentry>
+</variablelist>
+<![%config-file;[<literallayout>@@#address-family-preference  none</literallayout>]]>
+</sect3>
+
 <!--  ~  End section  ~  -->
 
 <!--   ~~~~~       New section      ~~~~~     -->