Ubuntu cannot access internet, LAN is fine
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Kevin Southworth
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Published on 2011-08-01T16:48:52Z
Indexed on
2013/07/01
10:23 UTC
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I have an Ubuntu 8.04 LTS server that is directly connected to our Comcast Business Gateway modem and I have configured it with 1 of our 5 allotted Static IPs. My other machines on our LAN can connect to this server (via ssh, web, ping, etc.) but I cannot access this server from outside our network, and this machine cannot get out to the internet either (ping google.com fails with unknown host).
Here is my /etc/networking/interfaces file:
auto lo
iface lo inet loopback
auto eth0
iface eth0 inet static
address 173.162.54.19
netmask 255.255.255.248
broadcast 173.162.54.23
gateway 173.162.54.22
and my /etc/resolv.conf:
nameserver 68.87.77.130
nameserver 68.87.72.130
output from sudo route -n:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
173.162.54.16 0.0.0.0 255.255.255.248 U 0 0 0 eth0
0.0.0.0 173.162.54.22 0.0.0.0 UG 100 0 0 eth0
I have a Windows 2008 machine with an almost identical Static IP, static DNS setup and it works correctly, can access it within the LAN and also from public internet, the Windows machine and the Ubuntu machine are both directly connected to the Comcast Business Gateway.
I have tried rebooting Ubuntu, rebooting my Comcast modem, but nothing seems to make it work. I'm an Ubuntu noob, is there some other config I need to apply to make this work?
UPDATE: Yes I am able to ping my default gateway 173.162.54.22
output of iptables --list -n:
Chain INPUT (policy DROP)
target prot opt source destination
ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-input all -- 0.0.0.0/0 0.0.0.0/0
Chain FORWARD (policy DROP)
target prot opt source destination
ufw-before-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-forward all -- 0.0.0.0/0 0.0.0.0/0
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ufw-before-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-output all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-after-forward (1 references)
target prot opt source destination
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK FORWARD]: '
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-after-input (1 references)
target prot opt source destination
RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:137
RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:138
RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:139
RETURN tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:445
RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67
RETURN udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:68
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK INPUT]: '
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-after-output (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-before-forward (1 references)
target prot opt source destination
ufw-user-forward all -- 0.0.0.0/0 0.0.0.0/0
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-before-input (1 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 ctstate RELATED,ESTABLISHED
DROP all -- 0.0.0.0/0 0.0.0.0/0 ctstate INVALID
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 3
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 4
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 11
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 12
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 8
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:67 dpt:68
ufw-not-local all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 224.0.0.0/4 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 224.0.0.0/4
ufw-user-input all -- 0.0.0.0/0 0.0.0.0/0
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-before-output (1 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW,RELATED,ESTABLISHED
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW,RELATED,ESTABLISHED
ufw-user-output all -- 0.0.0.0/0 0.0.0.0/0
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-not-local (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type LOCAL
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type MULTICAST
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type BROADCAST
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK NOT-TO-ME]: '
DROP all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-user-forward (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-user-input (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:80
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:22
RETURN all -- 0.0.0.0/0 0.0.0.0/0
Chain ufw-user-output (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0
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