connection issues

[Oluwagbenga Shobowale]

Thanks.. I did not intend to run without iptables, i just wanted to know why
I had the connectivity issues in the first place, then go on to ensure
everything works.. now I want to look in the logs...
Thanks again...

From: redhat-sysadmin-list-bounces at redhat.com
[mailto:redhat-sysadmin-list-bounces at redhat.com] On Behalf Of Andrew Bacchi
Sent: Friday, June 20, 2008 8:22 PM
To: redhat-sysadmin-list at redhat.com
Subject: Re: connection issues

I have to agree with Richard, here.  I'd find out why the firewall was
blocking traffic, and just poke a hole or two in it where needed.  I would
never run without a firewall.

Richard Riley wrote: 
Unless you have a serious firewall between this server and the internet, I'd
be VERY leery about NOT using iptables to control traffic.  You could be
exposing more than you want to those nasty hackers out there.

Richard 

 

  
-----Original Message-----
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 3:09 PM
To: redhat-sysadmin-list at redhat.com
Subject: RE: connection issues

Thanks..in fact I thought I stopped iptable, but in was 
iptable6 I stopped in services and I assumed it was iptable. 
Thanks.. its fine now...

From: redhat-sysadmin-list-bounces at redhat.com
[mailto:redhat-sysadmin-list-bounces at redhat.com] On Behalf 
Of Alder, Stephen
(GTS)
Sent: Friday, June 20, 2008 7:35 PM
To: redhat-sysadmin-list at redhat.com
Subject: RE: connection issues

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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-- 
veritatas simplex oratio est
        -Seneca

Andrew Bacchi
Systems Programmer
Rensselaer Polytechnic Institute
phone: 518.276.6415  fax: 518.276.2809

http://www.rpi.edu/~bacchi/