centos firewall with adsl. Problem access some website

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medion
Posts: 2
Joined: 2007/02/28 12:01:16

centos firewall with adsl. Problem access some website

Post by medion » 2007/02/28 12:14:57

I have install Centos and configure it to use it has a firewall.

I have configured something like this:

(Internet/ADSL) ppp0 - MyCentos - eth1 ---- LAN.

I have made some rules that says: everything from LAN to any accept and NAT.

My rules works with debian and redhat. I have tested it.

I have verified that my LAN is natted with the ip's ppp0.

The problem is that pc on LAN can connect to some website. For example, everything works well with www.google.be but some other sites doesn't work.
On the firewall every website can be view with for example lynckx.

I have verified my rule, my route, my NAT...

The only strange thing i have noticed is when i do a tcpdump i view many checksumm error.

I have configured the same bix with redhat and that's working.

I have do a simple install without proxy,...

Thanks for you help.

medion
Posts: 2
Joined: 2007/02/28 12:01:16

RESOLU

Post by medion » 2007/03/06 14:29:43

That's working now. We have change some parameters and we can now access all website.


It 's due to one of these parameters.
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling

echo 1 > /proc/sys/net/ipv4/tcp_sack

echo 1 > /proc/sys/net/ipv4/tcp_fack

echo 0 > /proc/sys/net/ipv4/tcp_syncookies

echo 0 > /proc/sys/net/ipv4/tcp_ecn

echo 1 > /proc/sys/net/ipv4/tcp_timestamps

pjwelsh
Posts: 2620
Joined: 2007/01/07 02:18:02
Location: Central IL USA

centos firewall with adsl. Problem access some website

Post by pjwelsh » 2007/03/06 16:20:55

Thank you very much for the resolution update. Now the rest of us can be of more help for someone else.

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