Best utilizing fat long pipes and large file transfer

Glen Turner gdt at
Mon Jun 16 02:48:06 UTC 2008

Robert E. Seastrom wrote:
> As a user of hpn-ssh for years, I have to wonder if there is any
> reason (aside from the sheer cussedness for which Theo is infamous)
> that the window improvements at least from hpn-ssh haven't been
> backported into mainline openssh?  I suppose there might be
> portability concerns with the multithreaded ciphers, and there's
> certainly a good argument for not supporting NONE as a cipher type out
> of the box without a recompile, but there's not much excuse for the
> fixed size tiny buffers - I mean, it's 2008 already...

Fedora 8 and 9 and Ubuntu 8.04 include the upstream OpenSSH which include
large window patches.  OpenSSH 4.7 ChangeLog contains:

> Other changes, new functionality and fixes in this release:
>  * The SSH channel window size has been increased, and both ssh(1)
>    sshd(8) now send window updates more aggressively. These improves
>    performance on high-BDP (Bandwidth Delay Product) networks.

Cheers, Glen

  Glen Turner

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