jabber-network-server is the hostname or IP address of your
server. If it is set to nil, jabber.el will use the name in
jabber-server.
jabber-port is the TCP port of the server to connect to. If
nil, the default port is selected based on the chosen
connection method.
If both jabber-network-server and jabber-port are nil, and
a sufficiently modern dns.el is available, jabber.el will use SRV
records to find the right hostname and port.
jabber-connection-type specifies what kind of connection to
use. network means normal unencrypted network connection
(usually on port 5222), and ssl means encrypted connection
through GnuTLS or OpenSSL (port 5223), while starttls will
initiate an unencrypted connection and switch to encrypted if offered
by the server. You can change the settings of the encryption program
through M-x customize-group RET tls, M-x customize-group RET starttls
or M-x customize-group RET ssl, respectively.
By default, GnuTLS will be used if the tls library is available,
and if that fails, OpenSSL will be used if the ssl library is
available. You can force the use of either program by setting
jabber-connection-ssl-program to gnutls or openssl,
respectively. If you use starttls the library with the same name is
required, and it depends on the GnuTLS command line client.