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Subject2.0.37-pre4 "MASQ: failed..." even though NO masquerading active
Hi!

On a threaded socks server using 2.0.37-pre4 I get "MASQ: failed TCP/UDP
checksum from a.b.c.d" messages.

Well, I was confused because:
- No masquerade routing entries has been entered with ipfwadm
- No active masquerade connections shows up in ipfwadm -M -l (of course)

- No TCP or UDP connections to or from the "a.b.c.d" host shows up in
netstat, nor in the socks log.
- No TCP or UDP ports in the masquerade range are active, so that printk
should never be called - right?

from ipmasq.c it looks as if only ports 61000-up should ever get this
message, by default.

/* Make sure packet is in the masq range */
portptr = (__u16 *)&(((char *)iph)[iph->ihl*4]);
if ((ntohs(portptr[1]) < PORT_MASQ_BEGIN ||
ntohs(portptr[1]) > PORT_MASQ_END))

Are the packets with the bad checksum so broken that the port number is
wrong too, or how come it reaches this printk?

I can't understand from the sources if these messages are harmless or
not. I can't see why the kernel should print out messages about normal
protocol operation, though.

A Cc: of replies would be appreciated since vger is so slow.

--
Daniel.Deimert@intermec.com Intermec Printer AB, Göteborg, Sweden
http://www.intermec.com/ Intermec Identification Systems Division




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