SSh internal window size.. (again)
From: Julian Elischer (julian_at_vicor.com)
Date: Wed, 28 Apr 2004 17:54:02 -0700 To: firstname.lastname@example.org
openssh version sshd version OpenSSH_3.5p1 FreeBSD-20030924
OpenSSH_3.5p1 FreeBSD-20030924, SSH protocols 1.5/2.0, OpenSSL 0x0090701f
So, I'm ssh-ing data from machine A to machine B using sftp.
with ping times of 60ms, I can't get over 600KB/sec
looking at the SYN packats going over the wire, the negotiation looks like:
A->B S 1041192722:1041192722(0) win 65535
<mss 1460,nop,wscale 2,nop,nop,timestamp 20289777 0> (DF)
B->A S 1916098679:1916098679(0) ack 1041192723 win 57344
<mss 1460,nop,wscale 0,nop,nop,timestamp 616601895 20289777> (DF)
the recv and send default buffer sizes are set to 128K, on both sides
window scaling is enable on both sides,
so one would think that larger windows would result and data would flow
no. it looks as if..
(1) there is an internal windowing going on in the ssh protocol with a 64K
window size.. Is this changeable?).
(2) sshd opens it's socket with a 57KB window anyhow, despite the
higher default window size.. is this true?
Can these things be changed? it's be nice to be able to use ssh
to transfer data at the available bandwith..