firewall without rules blocks packages

firewall without rules blocks packages

[Joerg Bruenner]

Hi,

I have configured iptables:

Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source 
            destination
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source 
            destination
Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source 
            destination

It should be wide open. But it is not:
If I ping from firewall-box to box A A replies the
expected way. If I ping from A to firewall A wont
get an answer. Firewall recives the ping packes I
verified.
I can play the same with ssh or telnet ...

What can I do? 

Thanks a lot for help
Joerg


	

	
		
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Re: firewall without rules blocks packages

[Antony Stone]

On Saturday 05 June 2004 2:06 pm, Joerg Bruenner wrote:

> Hi,
>
> I have configured iptables:
>
> Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
> Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
> Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
>
> It should be wide open. But it is not:
> If I ping from firewall-box to box A A replies the
> expected way. If I ping from A to firewall A wont
> get an answer. Firewall recives the ping packes I
> verified.
> I can play the same with ssh or telnet ...
>
> What can I do?

Check the routing tables; check that services (ssh / telnet) are running; 
check that A is not blocking packets; check the netmasks on the interfaces.

Regards,

Antony.

-- 
What is this talk of "software release"?
Our software evolves and matures until it is capable of escape, leaving a 
bloody trail of designers and quality assurance people in its wake.

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Re: firewall without rules blocks packages

[Antony Stone]

On Saturday 05 June 2004 2:19 pm, Antony Stone wrote:

> On Saturday 05 June 2004 2:06 pm, Joerg Bruenner wrote:
> > Hi,
> >
> > I have configured iptables:
> >
> > Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
> > Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
> > Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
> >
> > It should be wide open. But it is not:
> > If I ping from firewall-box to box A A replies the
> > expected way. If I ping from A to firewall A wont
> > get an answer. Firewall recives the ping packes I
> > verified.
> > I can play the same with ssh or telnet ...
> >
> > What can I do?
>
> Check the routing tables; check that services (ssh / telnet) are running;
> check that A is not blocking packets; check the netmasks on the interfaces.

Also check the nat and mangle tables to make sure there are no rules there 
causing your strange behaviour.

Antony.

-- 
Bill Gates has personally assured the Spanish Academy that he will never allow 
the upside-down question mark to disappear from Microsoft word-processing 
programs, which must be reassuring for millions of Spanish-speaking people, 
though just a piddling afterthought as far as he's concerned.

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