[Fwd: linux-ipsec: ppp] How unreliable is tcpdump?

David (david+nospam@killerlabs.com)
Fri, 14 May 1999 16:51:45 -0700


Richard Guy Briggs wrote:

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>
> > Is there some known problem with freeswan 1.00 and ppp? I'm finding that
> > most of my packets (but not all) exit the ppp0 interface truncated with
> > very odd ip's.
>
> Tcpdump under Linux is not reliable for monitoring the packets originating or
> terminating at the machine on which it is running. Run it on another
> machine somewhere in between, if possible, or run a copy on both ends
> and throw out all the packets in one direction on each (I don't
> remember which direction gets false readings...). This may be your
> problem in diagnosing. There have been problems with PPP which we
> definitely want to fix, but are a little overloaded at the moment.
>
> > tcpdump
> >
> > 10:14:39.675021 truncated-ip - 1964 bytes missing!132.205.8.0 > 69.0.0.84:
> > (frag
> > 2510:2036@48192+) [tos 0x47] [ttl 0] (ipip)
> > 10:14:39.675021 truncated-ip - 31980 bytes
> > missing!h135-181-152-199.outland.luce
> > nt.com > 199.140.175.177: (frag 39423:32048@928+) [tos 0xc3]
> > 10:14:40.015021 modem-98.promethium.dialup.pol.co.uk.1025 >
> > world1.bellatlantic.
> > net.domain: 32576 (45)
> >
> >
> > I'm coming from modem-98.promethium.dialup.pol.co.uk.
> >
> > Does this make sense to anyone?
> >
> >
> >
> >
> > James Milne
> > UNIX SysAdmin
> > (403)750-4291
> >
>
> slainte mhath, RGB
> - --
> Richard Guy Briggs -- 1999 Green Party candidate for Ottawa-Vanier
> <http://www.conscoop.ottawa.on.ca/rgb/election.html> Vote Green!
>
> Prevent Internet Wiretapping! -- FreeS/WAN:<http://www.xs4all.nl/~freeswan>
>
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