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Re: fragmatiation with port-forwarding



Hi

On Tue, 28 Aug 2001, Dani Arbel wrote:

> If you have a rule in the FORWARD table to allow all or icmp related
> packets , then you need not add any specific rule for faragments or icmp
> fragmentation needed.

It seems that the packets were dropped by the nat router after all (due to
some wierd rule).

> Your problem is probably blackholing by a blocked icmp message of the type
> fragmentation needed. I just wonder what kind of setup makes this 6 bytes
> difference. Can you tell more about your iptables host setup ?

ipchains. Doing quite standard port forwarding.

The network itself is connected by frame-relay to BezeqInet.

> Dani
>
> On Tue, 28 Aug 2001, Tzafrir Cohen wrote:
>
> > Hi
> >
> > I have a web server that has recently moved to serve as port-forwarded
> > beond an ipchins linux box.
> >
> > I suddenly noticed frgamation problems: pages from the server don't load
> > if I get them fast enough. reducing the MTU to 1494 seems to solve the
> > problem (and setting it back to 1500 reproduces it).
> >
> > While I'll probably leave those MTU settings to prevent unnecessary
> > fragamantation, I can't exactly figure out how exactly the web server is
> > supposed to get the Fragment packets.
> >
> > I can't find any trace to dropped unlogged ICMP packetson the linux box
> > or the web server (and I'm pretty sure I currently log them all)
> >
> > Is there an explicit rule I need to add to forward the relevant ICMP
> > packets to a port-forwarded connection?
> > (It worked before the server was inside the NAT network, so I currently
> > suspect my own settings.)
> >
> > Thanks
> >
> > --
> > Tzafrir Cohen
> > mailto:tzafrir@technion.ac.il
> > http://www.technion.ac.il/~tzafrir
> >
> >
> >
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>
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-- 
Tzafrir Cohen
mailto:tzafrir@technion.ac.il
http://www.technion.ac.il/~tzafrir



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