Ubuntu server on LAN but can't get to internet when other pc's can

Question

I have spent over 32 hours tyring to solve this problem. My ubuntu 10.04.4 server has postfix/dovecot etc and has been running fine up until 5/3/2012. My symptoms are I can SSH to the server locally, I can ping it etc. but it does not get to internet or the internet to it. I have gone through several pages on this site as well as others.
Here are some pertinent files, I am sure you will want more and I will get to you.

# The primary network interface
auto eth0
iface eth0 inet static
address 192.168.xxx.xxx
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
gateway 192.168.xxx.xxx

# Pubilc IP network interface
auto eth0:0
iface eth0:0 inet static
    name Ethernet Public IP card
    address 65.15.XXX.XXX
    netmask 255.255.255.240
    broadcast 65.15.XXX.XXX
    network 65.15.XXX.XXX

$ host www.gtlib.gatech.edu
www.gtlib.gatech.edu has address 128.61.111.13
www.gtlib.gatech.edu has address 128.61.111.11
www.gtlib.gatech.edu has address 128.61.111.10
www.gtlib.gatech.edu has IPv6 address 2610:148:1f00:6f00:21b:24ff:fe1d:e940
www.gtlib.gatech.edu has IPv6 address 2610:148:1f00:6f00:20c:29ff:fe3c:63a8
www.gtlib.gatech.edu has IPv6 address 2610:148:1f00:6f00:216:36ff:fee9:2178

$ ping 128.61.111.13
PING 128.61.111.13 (128.61.111.13) 56(84) bytes of data.

It timed out. When I do a apt-get or a wget it times out.

$ route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
65.15.xxx.xxx     *               255.255.255.240 U     0      0        0 eth0
192.168.0.0     *               255.255.255.0   U     0      0        0 eth0
default         towerysxxx.towe 0.0.0.0         UG    100    0        0 eth0

Please let me know what else I can provide.

Answer 1

auto eth0:0you should avoid doing this, as it depends on the deprecated ifconfig and the way it uses multiple ip addresses. I guess its still the way to do it with interfaces(5) however....

what is the ip address of this host?:

default         towerysxxx.towe 0.0.0.0         UG    100    0        0 eth0

your gateway should be on the public ip part, having your gateway in the localnet while you are the gateway makes no sense, that is your problem, you don't have your gateway set right.