openssh unix dev - Jul 2004 - Runnin SSH on slow CPU (386 40Mhz 8Mb RAM)

Hello everybody,

I'd like to use OpenSSH (client & server, for shell & sftp) on
an embedded PC with limited resources (processor 386 SX 40Mhz
8Mb RAM). I have Linux running on it.

In the past, I tried to use OpenSSH on it just to see if it could
work but each connection required an incredible long time to start. I
suppose that the key generation is too expensive for that processor.

Is there something I can try to make it work better ? Can we change
the key length or use another encryption algorythm which is less
CPU-expensive ? Which one of the available cipher is the less CPU
expensive ?

Can I change ServerKeyBits in sshd_config without breaking
interoperability ?

Any inputs point me somewhere where I can look further is welcomed. Feel
free to point me to the right documentation if such one exists, but my
search have been unsuccessfull until now (including the search on the
list archive).

Thank you for your help.

Cheers,
-- 
Rapha?l Hertzog -+- http://www.ouaza.com
Formation Linux et logiciel libre : http://www.logidee.com
Earn money with free software: http://www.geniustrader.org

Raphael Hertzog wrote:
> I'd like to use OpenSSH (client & server, for shell & sftp) on
> an embedded PC with limited resources (processor 386 SX 40Mhz
> 8Mb RAM). I have Linux running on it.
> 
> In the past, I tried to use OpenSSH on it just to see if it could
> work but each connection required an incredible long time to start. I
> suppose that the key generation is too expensive for that processor.
Run ssh -vvv and you will be able to see which steps are taking the most 
time.
> Is there something I can try to make it work better ? Can we change
> the key length or use another encryption algorythm which is less
> CPU-expensive ? Which one of the available cipher is the less CPU
> expensive ?
Usually arcfour for symmetric ciphers, but it's probably the public-key 
stuff (DH, RSA or DSA) that's killing you.
> Can I change ServerKeyBits in sshd_config without breaking
> interoperability ?
Probably yes (within reason) but that will only affect SSHv1 connections.
> Any inputs point me somewhere where I can look further is welcomed. Feel
> free to point me to the right documentation if such one exists, but my
> search have been unsuccessfull until now (including the search on the
> list archive).
http://www.openssh.com/faq.html#3.3

-- 
Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
     Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.