[SWLUG] Helping me debug network issue

Mon Jan 9 14:51:42 UTC 2012

Sounds like an MTU problem, (the 302 http reply is quite small in your
telnet example).

Try the -s flag in ping.

Curon

On 9 January 2012 14:33, Daniel Morgan <plodski at gmail.com> wrote:

> 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
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