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[ts-7000] Cheating on tcp_syn_retries -- anything better?

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Subject: [ts-7000] Cheating on tcp_syn_retries -- anything better?
From: "damotclese" <>
Date: Tue, 29 Sep 2009 21:12:33 -0000
Greetings, Group!

When connect() is called, the TCP/IP stack makes variable tcp_syn_retries 
number of SYN retries which are approximately from 40 to 50 seconds apart which 
means minimu number of seconds between _meaningfully_ calling connect() is 
about 180 seconds.

connect() under TS-Linux for the same IP/TCP Port number while there are 
pending SYN retries appears to cause problems, at least it does for me.  
Retried SYNs appear to stop being sent if a connect() is called 10 seconds in 
to a previous connect()'s retry period.

Anyone else notice that behavior?

What I did was I echo 1 > /proc/sys/net/ipv4/tcp_syn_retries prior to calling 
connect() then I echo 5 back in afterwards. The control block for the TCP 
connection attempt gets initialized to 1 so that my calling connect() every 10 
seconds actually works.

Also I noticed that calling close() on a sock that's in SYN_SENT state does not 
immediately force the TCP/IP stack to leave that state -- which was surprising.

Does anyone have a better solution?  I want to be able to perform one single 
SYN according to a configurable period of time, I don't want retries to be 
performs.

Thanks!





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