Allowing TCP/IP connections

In the postgres configuration file, which options do I have to enable to
allow TCP/IP connections:

#
#       Connection Parameters
#
#tcpip_socket = false
#ssl = false

#max_connections = 32 # 1-1024

#port = 5432
#hostname_lookup = false
#show_source_port = false

#unix_socket_directory = ''
#unix_socket_group = ''
#unix_socket_permissions = 0777

#virtual_host = ''

#krb_server_keyfile = ''