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 184.108.40.206 www.gtlib.gatech.edu has address 220.127.116.11 www.gtlib.gatech.edu has address 18.104.22.168 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 22.214.171.124 PING 126.96.36.199 (188.8.131.52) 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.