A Weird one

Daniel V Klein dvk@lonewolf.com
Fri Jul 23 22:06:20 UTC 2004


My firewall/router NATs my external addresses to my internal addresses (it is
a Cisco 2621 - a fairly substantial router for a home system, and it
certainly can handle what I'm asking it to do).  Inside, I have 3 class-C's,
outside I have a /28.  The servers are all NATed 1:1, so they have an inside
and an outside address.  But my router makes all that transparent...

The problem is still very strange, as "cdcc rtt" works perfectly on one box
running BSDi and not on another running FreeBSD 4.10.

% cdcc rtt
# 07/23/04 17:54:26 EDT  /var/dcc/map
# Re-resolve names after 19:54:25  Check RTTs after 18:09:26
# 189.50 ms threshold, 189.50 ms average    12 total, 4 working servers
IPv6 off

dcc1.dcc-servers.net,-      anon
#   142.27.70.214,-                                  COLLEGEOFNEWCALEDONIA ID
1189
#     100% of  5 requests ok  533.22 ms RTT            108 ms queue wait
#   194.109.153.82,-                                             NIET ID 1080
#      50% of 10 requests ok 2642.25 ms RTT           1780 ms queue wait
# * 208.201.249.232,-                                       sonic.net ID 1156
#      44% of 18 requests ok  139.50 ms RTT             52 ms queue wait

dcc2.dcc-servers.net,-      anon
#   194.119.212.5,-                                                   ID 1182
#      17% of 12 requests ok  232.59 ms RTT             80 ms queue wait
#   212.203.14.116,-                                
#      not answering

dcc3.dcc-servers.net,-      anon
#   137.118.60.88,-                                 
#      not answering
#   216.240.97.12,-                                 
#      not answering

dcc4.dcc-servers.net,-      anon
#   204.152.184.184,-                               
#      not answering
#   212.69.217.26,-                                 
#      not answering

dcc5.dcc-servers.net,-      anon
#   62.75.136.220,-                                 
#      not answering
#   194.85.132.210,-                                
#      not answering
#   208.201.249.233,-                               
#      not answering


======================

In another window on the same machine:

# tcpdump port 6277
tcpdump: listening on vr0
17:54:25.793569 maxwell.ibp.com.2402 > avas.cnc.bc.ca.6277: udp 40
17:54:25.913486 avas.cnc.bc.ca.6277 > maxwell.ibp.com.2402: udp 108 (DF)
17:54:25.913719 maxwell.ibp.com.2402 > werkt.niet.net.6277: udp 40
17:54:26.215933 werkt.niet.net.6277 > maxwell.ibp.com.2402: udp 108 (DF)
17:54:26.216126 maxwell.ibp.com.2402 > eth0.d.spam.sonic.net.6277: udp 40
17:54:26.300307 eth0.d.spam.sonic.net.6277 > maxwell.ibp.com.2402: udp 108 (DF)
17:54:26.300491 maxwell.ibp.com.2402 > ns.pa.iasf.cnr.it.6277: udp 40
17:54:26.438113 ns.pa.iasf.cnr.it.6277 > maxwell.ibp.com.2402: udp 108 (DF)


Note that only 3 machines were polled!  On my other machine, there is a
shitstorm of UDP packets on port 6277.  I'm stumped - what debugging can I
turn on to find this?  If I do "cdcc -ddddd rtt" I see nothing different
from a plain old "cdcc rtt".

-Dan

> > From: Daniel V Klein 
> 
> >                                                        NATed from ...
> 
> > If I delete dcc2.dcc-servers.net, then suddenly dcc3.dcc-servers.net answer
> s.
> > It seems to be only able to handle 4 machines total.
> 
> If by "it" you mean your NAT box, then that would also be my guess.
> 
> Note that I do not really understand where NAT is involved.
> 
> 
> Vernon Schryver    vjs@rhyolite.com
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> DCC mailing list      DCC@rhyolite.com
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