[CentOS] CentOS 4.4 blocking outbound connections?

Neil Aggarwal neil at JAMMConsulting.com
Sat Feb 17 20:33:34 UTC 2007


Fabian:

This is annoying.  I was playing around with the rules
and things started working.  I put the rules back to what
I had before and things still work.

I don't like it when things do that.  Makes me wonder if
it will switch back on its own.

Thanks,
	Neil 



--
Neil Aggarwal, (214)986-3533, www.JAMMConsulting.com
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-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Of Fabian Arrotin
Sent: Saturday, February 17, 2007 10:04 AM
To: CentOS mailing list
Subject: Re: [CentOS] CentOS 4.4 blocking outbound connections?

On Sat, 2007-02-17 at 09:15 -0600, Neil Aggarwal wrote:
> Hello:
> 
> When I installed CentOS 4.4 (from the ServerCD) on my server, I told 
> it not to install a firewall and I disabled SELinux.  The server is
> a SuperMicro 5015P-TR.
> 
> I set up my own /etc/init.d/firewall with these rules:
> 
> #!/bin/sh
> # Firewall script
> #
> # Source function library
> . /etc/init.d/functions
> 
> RETVAL=0
> 
> # Some definitions (Will need to change ETH0_IP to match your
configuration)
> ETH0_IP=38.114.192.86
> 
> # See how we were called.
> case "$1" in
>   start)
>         echo -n "Starting firewall: "
>         /sbin/modprobe ip_conntrack_ftp
> 
>         # Set the default policies to drop all packets
>         /sbin/iptables -P INPUT DROP
>         /sbin/iptables -P OUTPUT DROP
>         /sbin/iptables -P FORWARD DROP
> 
>         # Flush any existing rules
>         /sbin/iptables -F
> 
>         # Allow loopback traffic
>         /sbin/iptables -A INPUT -i lo -j ACCEPT
>         /sbin/iptables -A OUTPUT -o lo -j ACCEPT
> 
>         # Allow icmp protocol packets
>         /sbin/iptables -A INPUT -i eth0 -d $ETH0_IP -p icmp -j ACCEPT
>         /sbin/iptables -A OUTPUT -o eth0 -s $ETH0_IP -p icmp -j ACCEPT
> 
>         # Allow ssh connections from the outside world
>         /sbin/iptables -A INPUT -i eth0 -d $ETH0_IP -p tcp --sport 1024:
> --dport ssh -m state --state NEW,ESTABLISHED -j ACCEPT
>         /sbin/iptables -A OUTPUT -o eth0 -s $ETH0_IP -p tcp --sport ssh
> --dport 1024: -m state --state ESTABLISHED -j ACCEPT

Why not using ESTABLISHED,RELATED instead of just using ESTABLISHED ?

Can you also consider giving us the result of `iptables -L -v -n --line-
numbers` ? That gives a better view of what the system is using as
iptables rules ...

> 
>   <snip>

-- 
Fabian Arrotin <fabian.arrotin at arrfab.net>




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