Re: SSh internal window size.. (again)

From: monster (
Date: 04/29/04

  • Next message: Tobias Speckbacher: "private keys and users access to them"
    Date: Thu, 29 Apr 2004 06:56:14 +0000

    the tcp ip send recive can be changed with sysctrl for the kernel, but the higher the size the more risk you have of corruption
    as far as changing the size for just ssh
    no clue,, hope this helps
    On Wed, 28 Apr 2004 17:54:02 -0700
    Julian Elischer <> wrote:

    > sshd:
    > openssh version sshd version OpenSSH_3.5p1 FreeBSD-20030924
    > ssh:
    > 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
    > faster, but..
    > 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..

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