Zero sized downloads

Michael Green mishagreen at gmail.com
Thu Aug 25 11:33:06 BST 2005


On 8/25/05, Horms <horms at verge.net.au> wrote:

> That is very strange. I assume that apache log is from one of b1-4.

All four instances of apache2 write the log to the same file:
/srv/LogShared/apache/access_log
/srv/LogShared/apache/error_log
and others (ssl..etc)

> It could be some wird MTU problem, but its probably something more
> mundane. Could you send the output of a tcpdump on the linux director,
> for both a success (index.php) and fail (snps.zip).
> 
> Something like
> 
> tcpdump -n -e -i any host 192.115.133.204 or icmp

> Also, could you show the output of ipvsadm -L -c -n after each test.

I N D E X . P H P
*^*^*^*^*^*^*
This simple script simply polls 'hostname' and sends it giving me
(admin) idea what RS has just replied:
---- script begin ------
bioinfo4:/srv/www/htdocs # more /srv/www/htdocs/index.php
<html>
<head>
<title>Testing LVS</title>
</head>
<body>
<?php
$host=`hostname`;
print($host);
?>
</body>
</html>
----script end -----

Requesting index.php:
[michaelg at beastier ~] ->wget -t 1 http://biolvs.weizmann.ac.il/index.php
--11:01:56--  http://biolvs.weizmann.ac.il/index.php
           => `index.php'
Resolving biolvs.weizmann.ac.il... 132.77.150.100
Connecting to biolvs.weizmann.ac.il[132.77.150.100]:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: unspecified [text/html]

    [ <=>                                                             
        ] 75            --.--K/s

11:01:56 (732.42 KB/s) - `index.php' saved [75]

wget was performed twice.

tcpdump output can be found <http://biolvs.weizmann.ac.il/tcpdump-index.php>
The file gets downloaded and the input looks ok:
 <html>
<head>
<title>Testing LVS</title>
</head>
<body>
b4
</body>
</html>

And ipvsadm:
IPVS connection entries
pro expire state       source             virtual            destination
TCP 00:08  CLOSE       192.115.133.204:48034 132.77.150.100:80  192.168.1.24:80
bioinfo4:~ #           

S N P S . T G Z
*^*^*^*^*^*^*
[michaelg at beastier ~] ->wget -t 1 http://biolvs.weizmann.ac.il/snps.tgz
--13:00:40--  http://biolvs.weizmann.ac.il/snps.tgz
           => `snps.tgz.4'
Resolving biolvs.weizmann.ac.il... 132.77.150.100
Connecting to biolvs.weizmann.ac.il[132.77.150.100]:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 10,798,002 [application/x-gzip]

 0% [                                                                 
        ] 0             --.--K/s

13:00:40 (0.00 B/s) - Connection closed at byte 0. Giving up.

tcpdump:
13:00:40.385158 < 00:02:b3:b8:f6:6d 0800 76: IP 192.115.133.204.37332
> 132.77.150.100.80: S 3127335056:3127335056(0)
 win 5840 <mss 1460,sackOK,timestamp 76863627 0,nop,wscale 0>
13:00:40.385214 > 00:0d:60:19:93:f1 0800 76: IP 192.115.133.204.37332
> 192.168.1.24.80: S 3127335056:3127335056(0) w
in 5840 <mss 1460,sackOK,timestamp 76863627 0,nop,wscale 0>
13:00:40.385393 < 00:09:6b:b5:d2:ee 0800 76: IP 192.168.1.24.80 >
192.115.133.204.37332: S 59647951:59647951(0) ack 3
127335057 win 5792 <mss 1460,sackOK,timestamp 1479584364 76863627,nop,wscale 0>
13:00:40.385418 > 00:0d:60:19:93:f0 0800 76: IP 132.77.150.100.80 >
192.115.133.204.37332: S 59647951:59647951(0) ack
 3127335057 win 5792 <mss 1460,sackOK,timestamp 1479584364
76863627,nop,wscale 0>
13:00:40.386033 < 00:02:b3:b8:f6:6d 0800 68: IP 192.115.133.204.37332
> 132.77.150.100.80: . ack 1 win 5840 <nop,nop,
timestamp 76863627 1479584364>
13:00:40.386048 > 00:0d:60:19:93:f1 0800 68: IP 192.115.133.204.37332
> 192.168.1.24.80: . ack 1 win 5840 <nop,nop,ti
mestamp 76863627 1479584364>
13:00:40.402148 < 00:02:b3:b8:f6:6d 0800 184: IP 192.115.133.204.37332
> 132.77.150.100.80: P 1:117(116) ack 1 win 58
40 <nop,nop,timestamp 76863628 1479584364>
13:00:40.402161 > 00:0d:60:19:93:f1 0800 184: IP 192.115.133.204.37332
> 192.168.1.24.80: P 1:117(116) ack 1 win 5840
 <nop,nop,timestamp 76863628 1479584364>
13:00:40.402256 < 00:09:6b:b5:d2:ee 0800 68: IP 192.168.1.24.80 >
192.115.133.204.37332: . ack 117 win 5792 <nop,nop,
timestamp 1479584381 76863628>
13:00:40.402278 > 00:0d:60:19:93:f0 0800 68: IP 132.77.150.100.80 >
192.115.133.204.37332: . ack 117 win 5792 <nop,no
p,timestamp 1479584381 76863628>
13:00:40.403130 < 00:09:6b:b5:d2:ee 0800 376: IP 192.168.1.24.80 >
192.115.133.204.37332: P 1:309(308) ack 117 win 57
92 <nop,nop,timestamp 1479584382 76863628>
13:00:40.403139 > 00:0d:60:19:93:f0 0800 376: IP 132.77.150.100.80 >
192.115.133.204.37332: P 1:309(308) ack 117 win
5792 <nop,nop,timestamp 1479584382 76863628>
13:00:40.404400 < 00:02:b3:b8:f6:6d 0800 68: IP 192.115.133.204.37332
> 132.77.150.100.80: . ack 309 win 6432 <nop,no
p,timestamp 76863629 1479584382>
13:00:40.404412 > 00:0d:60:19:93:f1 0800 68: IP 192.115.133.204.37332
> 192.168.1.24.80: . ack 309 win 6432 <nop,nop,
timestamp 76863629 1479584382>
13:00:40.420869 < 00:09:6b:b5:d2:ee 0800 68: IP 192.168.1.24.80 >
192.115.133.204.37332: F 309:309(0) ack 117 win 579
2 <nop,nop,timestamp 1479584400 76863629>
13:00:40.420878 > 00:0d:60:19:93:f0 0800 68: IP 132.77.150.100.80 >
192.115.133.204.37332: F 309:309(0) ack 117 win 5
792 <nop,nop,timestamp 1479584400 76863629>
13:00:40.421636 < 00:02:b3:b8:f6:6d 0800 68: IP 192.115.133.204.37332
> 132.77.150.100.80: . ack 310 win 6432 <nop,no
p,timestamp 76863630 1479584400>
13:00:40.421648 > 00:0d:60:19:93:f1 0800 68: IP 192.115.133.204.37332
> 192.168.1.24.80: . ack 310 win 6432 <nop,nop,
timestamp 76863630 1479584400>
13:00:40.421651 < 00:02:b3:b8:f6:6d 0800 68: IP 192.115.133.204.37332
> 132.77.150.100.80: R 117:117(0) ack 310 win 6
432 <nop,nop,timestamp 76863630 1479584400>
13:00:40.421665 > 00:0d:60:19:93:f1 0800 68: IP 192.115.133.204.37332
> 192.168.1.24.80: R 117:117(0) ack 310 win 643
2 <nop,nop,timestamp 76863630 1479584400>
13:02:37.062459 < 00:02:b3:b8:f6:6d 0800 76: IP 192.115.133.204.37333
> 132.77.150.100.80: S 4289559963:4289559963(0)
 win 5840 <mss 1460,sackOK,timestamp 76875294 0,nop,wscale 0>
13:02:37.062493 > 00:0d:60:19:93:f1 0800 76: IP 192.115.133.204.37333
> 192.168.1.24.80: S 4289559963:4289559963(0) w
in 5840 <mss 1460,sackOK,timestamp 76875294 0,nop,wscale 0>
13:02:37.062566 < 00:09:6b:b5:d2:ee 0800 76: IP 192.168.1.24.80 >
192.115.133.204.37333: S 198195321:198195321(0) ack
 4289559964 win 5792 <mss 1460,sackOK,timestamp 1479701061
76875294,nop,wscale 0>
13:02:37.062586 > 00:0d:60:19:93:f0 0800 76: IP 132.77.150.100.80 >
192.115.133.204.37333: S 198195321:198195321(0) a
ck 4289559964 win 5792 <mss 1460,sackOK,timestamp 1479701061
76875294,nop,wscale 0>
13:02:37.063080 < 00:02:b3:b8:f6:6d 0800 68: IP 192.115.133.204.37333
> 132.77.150.100.80: . ack 1 win 5840 <nop,nop,
tim
42 packets received by filter
0 packets dropped by kernel

ipvsadm:
bioinfo4:~ # ipvsadm -L -c -n
IPVS connection entries
pro expire state       source             virtual            destination
TCP 00:03  CLOSE       192.115.133.204:37332 132.77.150.100:80  192.168.1.24:80


-- 
Warm regards,
Michael Green


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