[SWLUG] Helping me debug network issue

Mon Jan 9 14:33:00 UTC 2012

Hello all,

I am am having trouble connecting my work pc (Debian Squeeze) to any
external sites at the moment. I was wondering if anybody could shed
some light on how I can troubleshoot this.

Okay first off, the LAN works perfectly I can access local websites
and resources (in fact the keyboard and mouse I am using to type this
is running over synergy to my windows pc).

DNS seems fine, and so does ping:

dtmorgan at daniel-debian:~$ ping www.google.co.uk
PING www-cctld.l.google.com (173.194.67.94) 56(84) bytes of data.
64 bytes from wi-in-f94.1e100.net (173.194.67.94): icmp_req=1 ttl=47
time=17.9 ms
64 bytes from wi-in-f94.1e100.net (173.194.67.94): icmp_req=2 ttl=47
time=17.9 ms
^C
--- www-cctld.l.google.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 17.975/17.982/17.990/0.134 ms
dtmorgan at daniel-debian:~$

So I thought maybe there was a problem with port 80 traffic, so I
telnet to google on port 80 and this works also.

dtmorgan at daniel-debian:~$ telnet www.google.com 80
Trying 173.194.67.106...
Connected to www.l.google.com.
Escape character is '^]'.
GET /
HTTP/1.0 302 Found
Location: http://www.google.co.uk/
Cache-Control: private
Content-Type: text/html; charset=UTF-8
Set-Cookie: PREF=ID=aa6314ad0c697a80:FF=0:TM=1326119362:LM=1326119362:S=bHW89V6BfLlLhHXj;
expires=Wed, 08-Jan-2014 14:29:22 GMT; path=/; domain=.google.com
Date: Mon, 09 Jan 2012 14:29:22 GMT
Server: gws
Content-Length: 221
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN

<HTML><HEAD><meta http-equiv="content-type" content="text/html;charset=utf-8">
<TITLE>302 Moved</TITLE></HEAD><BODY>
<H1>302 Moved</H1>
The document has moved
<A HREF="http://www.google.co.uk/">here</A>.
</BODY></HTML>
Connection closed by foreign host.

but if I use wget I just get

dtmorgan at daniel-debian:~$ wget www.google.co.uk
--2012-01-09 14:29:23--  http://www.google.co.uk/
Resolving www.google.co.uk... 173.194.67.94
Connecting to www.google.co.uk|173.194.67.94|:80... connected.
HTTP request sent, awaiting response...

and it hangs.

It's not just port 80 traffic I can ssh to servers on the lan, but I
can't ssh to external servers the other side of the wan.

My route table looks like this:

dtmorgan at daniel-debian:~$ sudo route
[sudo] password for dtmorgan:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.0.0      *               255.255.252.0   U     1      0        0 eth0
default         172.16.3.254    0.0.0.0         UG    0      0        0 eth0

from looking around on google, I was going to try ntop. However
apt-get is also failing.

Hope somebody has got some ideas

Dan