bind apache2 to localhost only Ubuntu 12.04.3 LTS

Question

Trying to bind apache2 to localhost only, running Ubuntu 12.04.3 LTS on OpenVZ VPS. It fails on me (see /var/log/apache2/error.log). Default configuration is:

# cat /etc/hosts
fe00::0     ip6-localnet
ff00::0     ip6-mcastprefix
ff02::1     ip6-allnodes
ff02::2     ip6-allrouters

127.0.0.1 localhost.localdomain localhost
# Auto-generated hostname. Please do not remove this comment.
<some-ext-ipv6-address> <some-hostname>
::1     localhost ip6-localhost ip6-loopback
# netstat -lntup
tcp6       0      0 :::80                   :::*                    LISTEN      623/apache2

I change Listen 80 to Listen 172.0.0.1:80 in /etc/apache2/ports.conf.

Apache2 errors out. There is no other service listening on port 80, also there is no other (conflicting) Listen declaration, just the default ports.conf apache2 ships with + the single change described.

# cat /var/log/apache2/error.log
apache2: Could not reliably determine the server's fully qualified domain name, using <some-ext-ipv6-address> for ServerName
(99)Cannot assign requested address: make_sock: could not bind to address 172.0.0.1:80
no listening sockets available, shutting down
Unable to open logs

Answer 1

localhost address is 127.0.0.1 not 172.0.0.1