File apache2-listen.conf of Package apache2

# Listen: Allows you to bind Apache to specific IP addresses and/or
# ports. See also the <VirtualHost> directive.
#
# http://httpd.apache.org/docs-2.2/mod/mpm_common.html#listen
#
# Change this to Listen on specific IP addresses as shown below to 
# prevent Apache from glomming onto all bound IP addresses (0.0.0.0)
#
# When we also provide SSL we have to listen to the 
# standard HTTP port (see above) and to the HTTPS port
#
# Note: Configurations that use IPv6 but not IPv4-mapped addresses need two
#       Listen directives: "Listen [::]:443" and "Listen 0.0.0.0:443"
#
#Listen 12.34.56.78:80
#Listen 80
#Listen 443

Listen 80

Listen 443

</IfModule>
    </IfDefine>
</IfDefine>

# Use name-based virtual hosting
# 
# - on a specified address / port:
#
#NameVirtualHost 12.34.56.78:80
#
# - name-based virtual hosting:
#
#NameVirtualHost *:80
#
# - on all addresses and ports. This is your best bet when you are on
#   dynamically assigned IP addresses:
#
#NameVirtualHost *