[CentOS] Wierd Networking Problem
shawn at tandac.com
Wed Oct 31 07:24:22 UTC 2007
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:
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
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