Strange connection problems.

Ryan Belcher Ryanb at
Wed Apr 13 14:26:33 CEST 2005

Kind of depends on how you look at it.  If an ICMP Ping (as an example) goes out of the network, the echo will make it back, but if an unrelated, or unestablished ICMP is directed to the network from the outside, it will be dropped.  I know this could be considered "bad form" in the right context, but I'm not specifically worried about it.

In any case, everything's working as I expect now.



-----Original Message-----
From: Mohamed Eldesoky [mailto:eldesoky.lists at]
Sent: Wednesday, April 13, 2005 7:43 AM
To: Ryan Belcher; netfilter
Subject: Re: Strange connection problems.

Are you blocking ICMP ??

On 4/13/05, Ryan Belcher <Ryanb at> wrote:
> Gentlemen,
> Thank you!  That cleared things up perfectly.  ppp0 had the MTU set for 1492; however, none of the other interfaces did (including eth1 which I failed to mention was actually the path to ppp0).  You are both gentlemen and scholars.
> Thanks again!
> Ryan
> -----Original Message-----
> From: Jason Opperisano [mailto:opie at]
> Sent: Monday, April 11, 2005 6:04 PM
> To: netfilter at
> Subject: Re: Strange connection problems.
> On Fri, Apr 08, 2005 at 05:14:09PM -0400, Ryan Belcher wrote:
> > Hi All,
> >
> > Below I've posted my FW config.  It's handling 3 interfaces.  ppp0, eth0, an ath0.
> > It's on Linux kernel version 2.6.10.
> >
> > Pretty much everything works as I expect except for a strange issue with certain websites while trying to connect from clients within my network.  For example,, SSL logins, and a few others.  If you want to poke at this configuration, penny-arcade will appear to begin connection but after the SYN, ACK, then HTTP GET sequence, the HTTP response never gets here (according to Ethereal anyways).  If I try connecting from the actual firewalling box itself, it works fine.
> >
> > Does anyone have any ideas?
> sounds like the classic description of an MTU issue.
> -j
> --
> "Tom Tucker: This is Tom Tucker... Tucker's evil twin Todd Tucker
>  out to destroy his brother's reputation. Now I'm going to go back inside
>  my motel room where I'm going to have freaky sex with my prostitute
>  with whom I still have another 45 minutes."
>         --Family Guy

Mohamed Eldesoky

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