Multiple IP's on one ethernet port

Multi-home hosts are possible, make sure that the kernel has "IP: aliasing support" built in. It appears as if you need at least one device named, for example, ethX. If you define, say, an ethX:0 and and ethX:1 then ifconfig won't show them, but if one of them is ethX then both show up OK.

Network configuration in /etc/network/interfaces:

iface eth0:1 inet static
        address 192.168.1.50
        netmask 255.255.255.0

For some reason pump doesn't like the :0 aliases so if you're using dhcp then it has to be on ethX.

For more info see http://www.tldp.org/HOWTO/mini/IP-Alias/index.html

/etc/hostname: use short name on Debian, fqdn on centos: http://serverfault.com/questions/331936/setting-the-hostname-fqdn-or-short-name

Tests After Setting Up a New Box

$ hostname
$ hostname --fqdn
$ dnsdomainname
$ python -c "import socket; print socket.gethostname()"
$ python -c "import socket; print socket.gethostbyaddr('<output from previous command>')"

If these aren't what's expected the problem is probably in either /etc/hostname or /etc/hosts.