Re: limiting SSH client's bandwidth?

On Thu, 2009-02-12 at 12:40 +0100, Tomasz Chmielewski wrote:
Is it somehow possible to limit OpenSSH client's bandwidth?

Today I was copying data (whole block devices) over internet

dd if=/dev/san10/xen1 | bzip2 -9 | ssh "bzip2 -d | dd of=/dev/san18/xen1"

It worked fine, but the latency of other connections was horrible,
because the above connection ate almost all bandwidth available.

scp has this option:

-l limit
Limits the used bandwidth, specified in Kbit/s.

But it looks that it's not available to ssh.

I wouldn't like to use 3rd party programs or system settings,
because they are not portable, sometimes require root privileges
and are just additional burden for a one-off task.

SSH has always been meant for interactive shell - not file copying.
therefore, the -l (or similar) flag has no point there (unless your are
piping file copy operations through SSH) :D

Other problem is that SSH (being meant for interactive shell) sets the
TOS (type of service) bits to 'minimize delay'. SCP on contrary does not
do this, so even not throttled scp (full bandwidth) won't spoil your
concurrent ssh interactivity, because default qdisc attached to each
device on linux - pfifo_fast honours TOS bits - will send out SSH
traffic first, let the scp traffic queue.


This e-mail message may contain confidential and/or privileged information. If you are not an addressee or otherwise authorized to receive this message, you should not use, copy, disclose or take any action based on this e-mail or any information contained in the message.
If you have received this material in error, please advise the sender immediately by reply e-mail and delete this message. Thank you.
Allinea Software and Streamline Computing are trading divisions of Concurrent Thinking Limited: Registered in England and Wales No: 03913912
Registered Address: The Innovation Centre, Warwick Technology Park, Gallows Hill, Warwick, CV34 6UW, United Kingdom

Relevant Pages

  • Re: Is SSH worth it??
    ... > We would be using SSH and SCP. ... SCP for automated scripts. ... > client will not be prompted for a password. ... remote machine, but imho it is better to swap client+server and give ...
  • RE: SCP and MVS data sets?
    ... SCP and MVS data sets? ... Is it possible that the open function is different in SCP? ... You can also do the following weirdness to use ssh to copy a z/OS legacy ...
  • Re: why does scp not use all my cores on a multi-cpu machine?
    ... When I ran my little test earlier, I observed that while I typed scp, both ... scp and ssh got "energized" and in fact ssh used more time than scp. ... Now since encrypting and transmitting has some elements of paralellity ... Right -- ssh, et. al. is an I/O bound process, so long as the network ...
  • Re: linux to linux scp in batch mode: how?
    ... reason why it works now is because of the dsa key. ... > been configured automatically when I set up ssh, I would imagine that I am ... >> I have ssh and scp up and running on my two Redhat 7.2 Linux machines, ... >> between the machines. ...
  • Re: Using SSH or SCP in REXX under TSO
    ... Using SSH or SCP in REXX under TSO ... Does z/OS sftp have a BINARY subcommand? ...