Iptables not working?

RickyJaff · 10-28-2003, 04:54 AM

One thing...
Edit the following files..
/etc/sysctl.conf

In this file change the value of "net.ipv4.ip_forward" from 0 to 1
and also "net.ipv4.conf.default.rp_filter" 0 to 1
The above might help u if u have already not done that..

Also make sure that u r using correct dns server of your ISP because in windows ICS if you entered wrong DNS address- it works but take little long to resolve but if u have provided in wrong dns in LInux it never works..
I don't remember but same thing was with one of my friend a long time ago.. and at the end we found that it was only because of wrong DNS server address.

To know wht is ur exact dns server check ur /etc/resolv.conf file while u r connected to net and there entry "namerserver" will tell u the dns addres of your ISP.

powerchord81 · 10-29-2003, 01:36 PM

Quote:

Originally posted by Blindsight
You can ping out fine from the linux box? Try pinging google from linux.

Also, when pinging from windows, try 'ping -t -w 5000 www.google.com' that way it'll wait 5 seconds before timing out. I have to do that from my network because I'm deployed in the middle of nowhere and it's about 2 seconds from here to anywhere else on the internet, heh.

If your DNS is pointed to your linux box, the windows machine may not be getting out to the internet at all, it may just be getting dns resolution from your linux box.

try traceroute -n www.google.com from the linux box and see how far it gets out, then try tracert -d www.google.com from your windows box and see how far it gets.

This'll aid in finding an answer, and keep the ball rolling..

Thanks for trying to help.

I can ping google from linux no problem.

And tried the ping -t -w 5000 command, but it still times out.

I've tried it without the linux box as a primary dns and with... either way it times out.

tracert from linux to google works fine. From windows it times out after getting to the linux gateway (192.168.1.1)

powerchord81 · 10-29-2003, 01:40 PM

Quote:

Originally posted by RickyJaff
One thing...
Edit the following files..
/etc/sysctl.conf

In this file change the value of "net.ipv4.ip_forward" from 0 to 1
and also "net.ipv4.conf.default.rp_filter" 0 to 1
The above might help u if u have already not done that..

Also make sure that u r using correct dns server of your ISP because in windows ICS if you entered wrong DNS address- it works but take little long to resolve but if u have provided in wrong dns in LInux it never works..
I don't remember but same thing was with one of my friend a long time ago.. and at the end we found that it was only because of wrong DNS server address.

To know wht is ur exact dns server check ur /etc/resolv.conf file while u r connected to net and there entry "namerserver" will tell u the dns addres of your ISP.

Hi, I've checked my /etc/sysctl.conf file and those values are already set to 1.

And i've checked the DNS addresses are right, and they exactly match the ones in /etc/resolv.conf and /etc/ppp/resolv.conf

I've completely run out of ideas now.

joseph · 10-30-2003, 02:53 AM

can you post up your iptables scripts?

powerchord81 · 10-30-2003, 06:35 AM

Quote:

Originally posted by joseph
can you post up your iptables scripts?

#!/bin/sh

IPTABLES=sbin/iptables

iptables --flush
iptables --table nat --flush

iptables --table nat --append POSTROUTING --out-interface ppp0 -j MASQUERADE
iptables --append FORWARD --in-interface eth0 -j ACCEPT

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

collen · 10-30-2003, 06:58 AM

Hmm, i got the same problem.
and i'm running a redhat 9 distro.

i can resolve hostnames, but a ping or traceroute timesout..
also i tryed the same things as noted in this forum-topic.. no resuld..

somehow, the data get's stuck .. on it's way.. (or lost)
so we keep on testing...

Collen

powerchord81 · 10-31-2003, 09:12 AM

any more ideas?

collen · 10-31-2003, 09:18 AM

well i got mine working today..

i used the iptables-script at the beginning of this list.
and a adjusted my network start-stop script.
coz every time i restarted my network it stopped
forwarding.. (and that was my prob)

so you might look at your init.d/network script and
find some parameter about the forwarding..!

sorry.. that was all for me.. rest works ok dokay now..

Collen