Bug 99031 – iptables NAT chain not working with DNAT and SNAT

Bug 99031 - iptables NAT chain not working with DNAT and SNAT

Summary:	iptables NAT chain not working with DNAT and SNAT

Status:	CLOSED WORKSFORME

Aliases:	None

Product:	Red Hat Linux
Classification:	Retired
Component:	iptables (Show other bugs)
Sub Component:
Version:	9
Hardware:	i686 Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Thomas Woerner
QA Contact:	Ben Levenson
Docs Contact:

URL:
Whiteboard:
Keywords:	Security

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2003-07-11 20:50 EDT by Chris
Modified:	2007-04-18 12:55 EDT (History)
CC List:	0 users

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:
Story Points:	---
Clone Of:
Environment:
Last Closed:	2003-08-11 05:29:48 EDT
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
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Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
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Description Chris 2003-07-11 20:50:31 EDT

From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.2.1) Gecko/20030225

Description of problem:
Redhat 9 with all patches applied from RHN. 

Start IPtables with default settings (ACCEPT all) using /etc/init.d/iptables start.

Set rule 
iptables -t nat -A POSTROUTING -o eth0 -p tcp -j SNAT --to-source 172.20.0.248

Ran ethereal to see network traffic and it kept the source as my private ip of
192.168.1.101 rather than changing it to 172.20.0.248. Yes my ip_forward is set
to 1 in the proc filesystem.

I have tried the exact same steps using Knoppix boot disk and it works fine.

Version-Release number of selected component (if applicable):
iptables-1.2.7a-2

How reproducible:
Always

Steps to Reproduce:
1.in description
2.
3.
    

Additional info:

Not good when you have firewall rules that worked before then you perform an
upgrade and your firewall has holes in it now...

Comment 1 Thomas Woerner 2003-07-21 04:05:11 EDT

I have tested this with different kernel and iptables versions and it works for me:

kernel-2.4.20-9 to kernel 2.4.20-18.9
iptables-1.2.7a-2 to iptables-1.2.8-7

I have used tcpdump on 3 machines: source host, mangle host, destination host.

Please check this again.

Comment 2 Mark J. Cox (Product Security) 2003-08-11 05:29:48 EDT

no response from reporter - please reopen this bug if you are able to reproduce
the problem.

Comment 3 Need Real Name 2003-09-04 07:47:08 EDT

I was having similar problems with kernel-2.4.20-20.9 and iptables-1.2.7a-2 --
rules in the nat table didn't seem to work. Upgrading to iptables-1.2.8-9.1
seems to solve the problem.

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