connection issues

Alder, Stephen (GTS) Stephen_Alder at ml.com
Fri Jun 20 18:34:38 UTC 2008


Have you upgraded the kernel lately?  

I've seen an upgraded kernel (big jumps in arch) make changes to
/etc/sysctl.conf - where the ip forwarding kernel parameter is
hardcoded.

 

Unlikely but easy enough to check and cross off as a possibility.

cat /etc/sysctl.conf | grep ip_forward

 

Steve

 

From: redhat-sysadmin-list-bounces at redhat.com
[mailto:redhat-sysadmin-list-bounces at redhat.com] On Behalf Of
Oluwagbenga Shobowale
Sent: Friday, June 20, 2008 2:00 PM
To: redhat-sysadmin-list at redhat.com
Subject: connection issues

 

Hi,

Can anyone help me with this issue? I have a redhat box that  connects
to the internet, hence it acts as a router. This server runs sendmail,
squid, pop3, samba etc..and all worked well at least before now.

However, recently it just stop working... When I logon locally to the
machine I can surf the internet, however other computers linux or
windows can't connect to any of its services. However, I can ping and it
responds back...

For example, on the server, I run an nslookup on any domain it get
resolved, however it does not work from any of the clients connected to
it. I stop iptables to test ..still it does not work. I ran tcpdump on
port 53 and I see traffic going in but the server does not respond with
the answer. Same goes for ssh and other services. At the end I get the
amount of filters passed and zero for the kernel. Hence I think traffic
is getting into the kernel but its not passing it back out.

 

Can someone help with this problem? Should I do a fresh installation?

Thanks
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