linux-kernel - Re: Seeing TCP socket options (nodelay, cork, etc) in Linux procfs or elsewhere?

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Message-ID: <1268670031.3154.35.camel@edumazet-laptop>
Date:	Mon, 15 Mar 2010 17:20:31 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"MacCana, Mike" <mike.maccana@...dit-suisse.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: Seeing TCP socket options (nodelay, cork, etc) in Linux procfs
 or elsewhere?

Le lundi 15 mars 2010 à 15:49 +0000, MacCana, Mike a écrit :
> Hi kernel folks,
>  
> I was wondering if there was a standard location to see TCP socket
> options (eg, nodelay, cork, etc), perhaps via procfs or some other
> means? I'd like to check whether arbitrary apps (for which I don't have
> code) are using particular TCP options. 
>  
> Wandering round /proc/net hasn't turned up anything yet, and after a
> quick:
> socket.setsockopt(0, 1, 1)
> to enable NODELAY I can't see any obvious difference in procfs or
> netstat output (where other Unixes seem to put this info). hat's the
> best way to see TCP options on sockets created by others' code?
> 

There is limited support given by ss command (part of iproute2) :

ss -emoi

ESTAB       0      0                                55.225.18.5:4900
55.225.18.5:50000    uid:501 ino:135421 sk:c3b405c0
	 mem:(r0,w0,f4096,t0) ts bic wscale:6,6 rto:201 rtt:1/0.5 ato:40 cwnd:3
send 393.2Mbps rcv_space:32768


But CORK flag is not exported yet (its usually a volatile flag, at least
with Apache server)



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