iptables error for nat/masq

id10t · Tux's lil' helper Joined: 18 May 2002 Posts: 100

Hi all...

When I tried setting up my old firewall script (I use gShield from muse.linuxmafia.org), the iptable command to start masq/nat results in a "iptables - invalid argument" output to my console. The exact same script works fine in my Slack 8.1 install (dual boot between slack and gentoo), and I'm using the exact same kernel .config (vanilla 2.4.21 sources) as my Slack install.

Any ideas? My wife is getting kinda perturbed about not being able to get online

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neilhwatson · l33t Joined: 06 Feb 2003 Posts: 719 Location: Canada

You need to determine which is the offending rule. Try entering the rules manually and/or use the -v option to increase verbosity.
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Decibels · Veteran Joined: 16 Aug 2002 Posts: 1623 Location: U.S.A.

I made some changes recently in my firewall script (hadn't for awhile and that is why hadn't noticed the change), but I was re-enabling masq for my other box and kept getting the same thing.
Little fuzzy on the details now. But in my script I had to add this line:

id10t · Tux's lil' helper Joined: 18 May 2002 Posts: 100

OK, I did a iptables-save > working on my Slack install, chrooted over to my gentoo install, and when I try to do a iptables-restore < working, I get

iptables-restore: line 7 failed

Line 7 is: -A POSTROUTING -s 192.168.0.0/255.255.255.0 -o ppp0 -j MASQUERADE

Just for grins I also emerged firestarter, and I get the same error from my original post, again on the line that sets up nat/masq.
:cry:

Any ideas as to why ?
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asterism · n00b Joined: 19 Aug 2003 Posts: 5

Try going back to iptables-1.2.7a-r4 if you are not already using that version.

I had a similar problem as you did with 1.2.8-r1. It didn't grok my NAT commands. (Also wouldn't compile against the 2.6 sources.)

Hope this Helps

Decibels · Veteran Joined: 16 Aug 2002 Posts: 1623 Location: U.S.A.

id10t · Tux's lil' helper Joined: 18 May 2002 Posts: 100

Fixed. Removing and re-emerging the iptables-1.2.7a-r4 ebuild specifically did it.
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masseya · Posted: Mon Feb 09, 2004 5:38 pm Post subject:

Moving from Networking and Security.

Please follow up to iptables invalid argument..

There are a great number of threads that are essentially dupes of this topic, so if you feel that something in this thread should go in the sticky thread, please re-post it there or provide a link back here. As always, please PM a moderator if you feel this thread is significantly different than any other thread and was inadvertently locked.

Thanks to nephros for pointing out the dupes.