Re: Wierd Networking Problem

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On Wednesday 31 October 2007, Alain Spineux wrote:
> Did you tried to ping other host inside and outside your network, your
> gateway ? If not working, did you tried to arping your gateway ?
> Did you look for packet with "tcpdump -n -i eth0" ?
>

I  can successfully traceroute from the server to google.  I didn't try an 
arping.

I'll review the tcpdump messages today and let you know...

Shawn

> On 10/31/07, Shawn Everett <shawn@xxxxxxxxxx> wrote:
> > Hi Guys,
> >
> > I'm 100% sure this is not a Linux issue but I want a second opinion...
> >
> > I have a Linux server running CentOS.  It was been absolutely perfect
> > without any errors or problems.
> >
> > Since Monday it has been unable to send email.  It is configured to
> > act as a smart host.  All email gets forwarded to smtp.isp.net.
> >
> > The server is on a network behind a firewall completely nat'd.  No
> > ports are forwarded to it.
> >
> > telnet smtp.isp.net 25 generates the following:
> > Trying a.b.c.d...
> > Connected to smtp.isp.net.
> > Escape character is '^]'.
> >
> > And then nothing.  All other machines can connect to smtp.isp.net 25
> > without a problem.  They also use that host for their outgong mail
> > server.
> >
> > Using links to surf the web has a similar result.  It just hangs
> >
> > traceroute and nslookups work correctly.
> >
> > There are no errors anywhere.
> >
> > The network in question has various routing and vlan configurations,
> > proxy servers and such.  I tend to suspect they're the problem. 
> > They're also not in my control.
> >
> > The firewall does show the Linux box attempting to make SMTP
> > connections but nothing else.
> >
> > Any ideas or suggestions would be appreciated.  I have not yet
> > rebooted the server.
> >
> > Shawn
> > _______________________________________________
> > CentOS mailing list
> > CentOS@xxxxxxxxxx
> > http://lists.centos.org/mailman/listinfo/centos


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