[H-GEN] Mail problems.......*almost* solved

[Robert Brockway]

On Wed, 24 Sep 1997, Michael Anthon wrote:

> 5. Start to recieve the message.  After about the 5th line or so of the 
> attachment, it hangs and at that exact time I get this error message in the 
> log......Sep 24 00:04:37 linux kernel: MASQ: failed TCP/UDP checksum from 
> 203.20.132.2!

This is suggesting the packet got mangled while going through ppp.  Here
are some possible reasons: Line noise, ppp fragmentation, modem settings.
There may be othe reasons.

Line noise can't be discounted as a cause.  Try taking your phone out
of the wall socket as they cause all sorts of noise (call waiting,
and they draw power from the line every 20 minutes to keep those stored
numbers in memory).

As for fragmentation, make sure you have 'always defragment' set in
the kernel config.  Recompile a kernel with this feature if necessary to
check it.  You should have this on with masq anyway. If the packets were
getting fragmented due to smallish mtu at the upstream site you could see
problems like this.

Modems settings are always fun to play with.

> Ohhh... more stuff in the log.  I have NO idea what this means, but looks 
> related
> 
> Sep 24 00:13:40 linux pppd[1599]: rcvd [proto=0x7] 0d 0a 62
> Sep 24 00:13:40 linux pppd[1599]: Unknown protocol (0x7) received

The port number (which determins the protocol) is only stored in the first
fragment.  If the packets weren't being defraged before going down stream
you might see unknown protocol errors perhaps. hmm.
Cheers,
	-Robert

--Robert Brockway. Email: robert at zen.humbug.org.au, robert at icc.net.au
                          r.brockway at mailbox.uq.edu.au, robert at plugged.net.au
                   WWW:   http://www.humbug.org.au/~robert
                   President of HUMBUG (http://www.humbug.org.au)

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