+* PAM:
+ --with-pam[=<path>]
+
+ Enable support for PAM, the Pluggable Authentication Modules library.
+ See doc/PAM.txt for details.
+
+* SSL:
+ --with-openssl[=<path>]
+ --with-gnutls[=<path>]
+
+ Enable support for SSL/TLS using OpenSSL or gnutls libraries.
+ See doc/SSL.txt for details.
+
+* IPv6:
+ --enable-ipv6
+
+ Adds support for version 6 of the Internet Protocol.
+