Re: [gentoo-user] Curious ping problem with no FW

[Mick <michaelkintzios@gmail.com>]

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On Monday 14 July 2008, Harry Putnam wrote:
> I've had a problem with being able to ping out to the internet from my
> gentoo box, while at the same time I'm able to ping outbound from
> several windows boxes on same home lan.
>
> I don't run a firewall at all from linux but do have a Netgear
> switch/router/Firewall upstream between me and the internet cable
> modem.
[snip..]

> My router/fw can be set to deny specific machines outbound traffic but
> that is not done in this case.  So the solution must reside somewhere
> in my gentoo install.

It may be worth checking your router's firewall rules once more.  Is the 
gentoo box connected to the router in the same fashion as the MSWindows 
boxen, or is it in some funny DMZ set up?

What do the firewall logs show?

> What things should I be checking.

If as you say you have no firewall on the Gentoo box then you ought to have a 
quick look at your kernel.  Use sysclt:

/sbin/sysctl -a

and look at your settings probably for net.ipv4.icmp_* or your specific NIC.

> A ping attempt like this:
>
>   ping ftp.ucsb.edu
>   PING ftp.ucsb.edu (128.111.24.43) 56(84) bytes of data.
>
> Just never moves any further, but you can see it has resolved the
> alpha address to numeric forum so must have contacted and received
> info from the nameserver.

Or from your router if it acts as a caching DNS resolver?

Unless you have configured your Gentoo kernel in a way that I am not sure is 
possible, my money would go on something being amiss with the router firewall 
settings.
-- 
Regards,
Mick

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