Enable Loopback confuse

Joris Dobbelsteen joris.dobbelsteen at mail.com
Fri Aug 19 13:55:39 CEST 2005


Yes, normally loopback traffic is not forwarded

Telnet generates packet
Iptables evaluates OUTPUT filter
Packet it routed, destination is to local system
Iptables evaluates INPUT filter
Someby received the packet

This is how (I guess) it would work...

- Joris

>-----Original Message-----
>From: netfilter-bounces at lists.netfilter.org 
>[mailto:netfilter-bounces at lists.netfilter.org] On Behalf Of 
>nattapon viroonsri
>Sent: vrijdag, 19 augustus 2005 12:42
>To: netfilter at lists.netfilter.org
>Subject: Enable Loopback confuse
>
>
>Anyone please recommend me about iptables loopback
>
>When i enable loopback i just use 2 line below and everything 
>work fine iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT 
>-o lo -j ACCEPT
>
>But i see many example around then have also included this 
>line below  to enable loopback iptables -A FORWARD -o lo - j ACCEPT ?
>
>i try generate packet locally like "telnet localhost 25" and 
>debug with "iptables -L -nv"
>but dont see any packet match  this rule(FORWARD)    only  
>INPUT and OUTPUT 
>matched
>
>So can i omit this line ?
>or what kind of packet that match this rule ?
>
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