Date: Fri, 30 Dec 1994 22:36:55 +0100 From: Stephen Melvin <melvin@zytek.fr> To: freebsd-hackers@freebsd.org Subject: source IP address mangled on certain packets!!?? Message-ID: <199412302136.WAA02083@seine.zytek.fr>
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I recently upgraded to 1.1.5.1R and I'm having a rather strange
problem with packets from "ping" and "traceroute". The setup is
as follows. I have a dialup-PPP connection which is periodically
established with pppd and then disconnected with kill -INT. Most
of this happens automatically and it has been working great for
the last 3 months. Now, after I upgraded I noticed that somtimes
(but not every time) pppd is invoked, certain (but not all) outgoing
packets get sent with garbage in the source IP address field
(consequently, they never return). However, packets from most
applications work all the time. I don't know if the problem
is with the new pppd or the new kernel, but it doesn't seem to be
with ping itself as the same thing happens with the 1.1R version
of ping. Interestingly, I can ping the address on the other end
of the ppp link OK. Here is a sample output from "tcpdump" for
three different commands.
"ping 193.107.193.22" (this one is correct)
-------
09:30:36.947118 193.104.118.2 > 193.107.193.22: icmp: echo request
09:30:37.260806 193.107.193.22 > 193.104.118.2: icmp: echo reply
09:30:37.950530 193.104.118.2 > 193.107.193.22: icmp: echo request
09:30:38.264977 193.107.193.22 > 193.104.118.2: icmp: echo reply
09:30:38.960544 193.104.118.2 > 193.107.193.22: icmp: echo request
09:30:39.273976 193.107.193.22 > 193.104.118.2: icmp: echo reply
-------
"ping 193.107.193.17" (where the heck did 86.0.26.0 come from?)
-------
09:26:38.520605 86.0.26.0 > 193.107.193.17: icmp: echo request
09:26:39.533073 86.0.26.0 > 193.107.193.17: icmp: echo request
09:26:40.543428 86.0.26.0 > 193.107.193.17: icmp: echo request
-------
"traceroute 193.107.193.17" (whoa, these are not IP numbers!!)
-------
09:21:50.003290 65.0.128.0.33881 > 193.107.193.17.33435: udp 12 [ttl 1]
09:21:55.013135 149.0.21.0.33881 > 193.107.193.17.33436: udp 12 [ttl 1]
09:22:00.022998 44.0.173.1.33881 > 193.107.193.17.33437: udp 12 [ttl 1]
09:22:05.033429 0.0.0.0.33881 > 193.107.193.17.33438: udp 12
09:22:10.043181 76.0.128.0.33881 > 193.107.193.17.33439: udp 12
09:22:15.052946 67.0.7.0.33881 > 193.107.193.17.33440: udp 12
-------
So, to summarize:
1. problem doesn't occur with 1.1R kernel, pppd and ping.
2. problem does occur with 1.1R ping on 1.1.5.1R kernel and pppd.
3. problem doesn't occur all the time, but it seems to either
always occur or never occur for a given invocation of pppd
and once it starts, I have to reboot to fix it.
4. problem seems to be only with outgoing packets from ping
and traceroute. (Note: incoming echo request packets from a
remote destination get bounced back properly).
5. outgoing packets to the machine on the other end of the ppp
link work OK all the time.
--------------
Stephen Melvin
melvin@zytek.fr
---------------
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