Amos,
thanks for your reply. See my notes below.
On Wed, Jan 9, 2013 at 1:55 AM, Amos Jeffries <squid3@xxxxxxxxxxxxx> wrote:
On 9/01/2013 5:27 p.m., Simon Matthews wrote:
I am finding that some websites do not respond when queried through squid.
I looked at this page, which suggests some solutions:
http://squidproxy.wordpress.com/2007/06/05/thinsg-to-look-at-if-websites-are-hanging
but I don't think it gives any useful suggestions. I tried setting the
mss to 1200 without success.
The basic reason that I don't think these suggestions are appropriate
for the problems I am seeing is simply that queries from the same
machine using telnet or wget (but not from squid) do get responses, so
the problem appears to be related to squid, rather than the networking
setup.
So where are the packets disappearing?
The article is a bit old but those are still the main reasons. Nowdays
things are also compounded by IPv6 and ICMPv6 packets also having
ECN/PMTU/WSS issues, you need to check whether Squid is performing IPv4 or
IPv6 then followup carefully in each of those protocols. Note that wget and
telnet can easily use a different version of IP with better results.
If you can mention some specific sites (or better specific URLs) which are
failing maybe someone can take a look and see if its just your or a bigger
issue.
The site that is giving problems is http://www.dmv.ca.gov
Here are some tcpdumps:
wget, bypassing the proxy:
tcpdump -i eth0 host 134.186.15.29
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
19:51:53.580924 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[S], seq 3438916088, win 14600, options [mss 1460,sackOK,TS val
1020431 ecr 0,nop,wscale 7], length 0
19:51:53.603836 IP 134.186.15.29.http > 98.248.55.206.34654: Flags
[S.], seq 3339908004, ack 3438916089, win 65535, options [mss 1380],
length 0
19:51:53.603907 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[.], ack 1, win 14600, length 0
19:51:55.449109 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[P.], seq 1:16, ack 1, win 14600, length 15
19:51:55.673140 IP 134.186.15.29.http > 98.248.55.206.34654: Flags
[.], ack 16, win 65535, length 0
19:51:56.776100 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[P.], seq 16:17, ack 1, win 14600, length 1
19:51:56.800028 IP 134.186.15.29.http > 98.248.55.206.34654: Flags
[P.], seq 1:1136, ack 17, win 65535, length 1135
19:51:56.800099 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[.], ack 1136, win 15890, length 0
19:51:56.800118 IP 134.186.15.29.http > 98.248.55.206.34654: Flags
[F.], seq 1136, ack 17, win 65535, length 0
19:51:56.801280 IP 98.248.55.206.34654 > 134.186.15.29.http: Flags
[F.], seq 17, ack 1137, win 15890, length 0
19:51:56.828107 IP 134.186.15.29.http > 98.248.55.206.34654: Flags
[.], ack 18, win 65535, length 0
wget via the proxy:
tcpdump -i eth0 host 134.186.15.29
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
19:51:03.118935 IP 98.248.55.206.34653 > 134.186.15.29.http: Flags
[S], seq 2175513684, win 14600, options [mss 1460,sackOK,TS val
1007816 ecr 0,nop,wscale 7], length 0
19:51:03.140282 IP 134.186.15.29.http > 98.248.55.206.34653: Flags
[S.], seq 3122380782, ack 2175513685, win 65535, options [mss 1380],
length 0
19:51:03.140361 IP 98.248.55.206.34653 > 134.186.15.29.http: Flags
[.], ack 1, win 14600, length 0
19:51:03.140684 IP 98.248.55.206.34653 > 134.186.15.29.http: Flags
[P.], seq 1:204, ack 1, win 14600, length 203
19:51:03.385677 IP 98.248.55.206.34653 > 134.186.15.29.http: Flags
[P.], seq 1:204, ack 1, win 14600, length 203
