Date: Wed, 20 Sep 2000 14:48:11 -0700 (PDT) From: Stephen Krauth <stephenk@stephenk.com> To: freebsd-questions@freebsd.org Subject: Strangest network problem - FreeBSD 4.1 Message-ID: <Pine.BSF.4.21.0009201406090.296-100000@beelzebub.inside.killermartian.com>
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Sorry for the cryptic subject, but I'm not sure how to one-line this.
The Problem: When trying to submit information to some websites (please
don't hit delete as soon as you see the word 'website'), one of my
machines will hang, the other will work. The example I'll use below is
when trying to buy something from outpost.com. It goes like this: click
'Click to buy' button, netscape hangs for a minute or so (but not like a
DNS hang - I can still interact with Netscape), and returns 'The document
conained no data.' From tcpdump, it looks like the bad machine simply
never gets an 'ACK' (see below) that the good one does. The bad machine
ALWAYS fails like this, the other always works.
The Setup: At first I was using NAT, but I disabled it as a test and the
problem still happened. Both machines were tested with a direct
connection to the cable coming from my DSL modem. For the machine that
was originally the NAT gateway (which is the bad machine) I booted from
kernel.GENERIC, and the problem still happened. I've included some
tcpdump output below, but I've edited it to (hopefully) make it easy to
read. BAD_HOST is the machine with the problems, GOOD_HOST is the machine
that works, and VENDOR is the website I was trying to contact at the time
(some long, ugly, outpost.com machinename).
Details: Both machines are running FreeBSD 4.1-RELEASE, and during the
test were running a minimum of services. The BAD_HOST machine has two
ethernet interfaces. dmesg & ifconfig are:
dc0: <Intel 21143 10/100BaseTX> port 0x6500-0x657f mem 0xe1004000-0xe10043ff
irq 10 at device 19.0 on pci0
ed1: <Ethernet PnP ISA Card /S> at port 0x240-0x25f irq 3 on isa0
dc0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 10.0.69.1 netmask 0xffffff00 broadcast 10.0.69.255
inet6 fe80::2c0:f0ff:fe4d:8f0%dc0 prefixlen 64 scopeid 0x1
ether 00:c0:f0:4d:08:f0
media: autoselect (100baseTX) status: active
supported media: autoselect 100baseTX <full-duplex> 100baseTX
10baseT/UTP <full-duplex> 10baseT/UTP none
ed1: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
inet 207.171.38.149 netmask 0xffffff00 broadcast 207.171.38.255
inet6 fe80::240:5ff:fe47:cddf%ed1 prefixlen 64 scopeid 0x2
ether 00:40:05:47:cd:df
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
inet6 fe80::1%lo0 prefixlen 64 scopeid 0x3
inet6 ::1 prefixlen 128
inet 127.0.0.1 netmask 0xff000000
The working machine (GOOD_HOST) has only one interface:
xl0: <3Com 3c905-TX Fast Etherlink XL> port 0xfcc0-0xfcff irq 11 at device
16.0 on pci0
(I don't have ifconfig for this one, since the network is back to the NAT
setup at the moment and wouldn't be useful).
Tcpdump:
BAD_HOST (this is the trace from clicking 'buy' and the hang):
BAD_HOST.1071 > VENDOR.http: S 1418824846:1418824846(0) win 16384 <mss 1460> (DF)
VENDOR.http > BAD_HOST.1071: S 2669526896:2669526896(0) ack 1418824847 win 8760 <mss 1460> (DF)
BAD_HOST.1071 > VENDOR.http: . ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: P 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: P 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: P 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: P 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: P 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: F 1054:1054(0) ack 1 win 17520 (DF)
BAD_HOST.1070 > VENDOR.http: FP 1:1054(1053) ack 1 win 17520 (DF)
BAD_HOST.1071 > VENDOR.http: FP 1:1054(1053) ack 1 win 17520 (DF)
VENDOR.http > BAD_HOST.1070: R 0:0(0) ack 1054 win 0
BAD_HOST.1071 > VENDOR.http: FP 1:1054(1053) ack 1 win 17520 (DF)
^C
GOOD_HOST (this is the trace from clicking 'buy' and working fine):
GOOD_HOST.1092 > VENDOR.http: S 1239899754:1239899754(0) win 16384 <mss 1460> (DF)
VENDOR.http > GOOD_HOST.1092: S 1298853381:1298853381(0) ack 1239899755 win 8760 <mss 1460> (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 1 win 17520 (DF)
GOOD_HOST.1092 > VENDOR.http: P 1:1027(1026) ack 1 win 17520 (DF)
VENDOR.http > GOOD_HOST.1092: . ack 1027 win 8760 (DF)
VENDOR.http > GOOD_HOST.1092: P 1:117(116) ack 1027 win 8760 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 117 win 17520 (DF)
VENDOR.http > GOOD_HOST.1092: . 117:1577(1460) ack 1027 win 8760 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 1577 win 17520 (DF)
VENDOR.http > GOOD_HOST.1092: . 3037:4497(1460) ack 1027 win 8760 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 1577 win 17520 (DF)
VENDOR.http > GOOD_HOST.1092: P 4497:5957(1460) ack 1027 win 8760 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 1577 win 17520 (DF)
VENDOR.http > GOOD_HOST.1092: . 1577:3037(1460) ack 1027 win 8760 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 5957 win 13140 (DF)
GOOD_HOST.1092 > VENDOR.http: . ack 5957 win 17236 (DF)
[and then some doubleclick crap...]
^C
Ok, this is already pretty long. If you have any ideas I'll appreciate
it. If there's any other info I can send please mention it. Thanks!
Steve K. U.F.O. - "For the feeler gauge in you."
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