Speeding up scp (Was: Re: Ramfs and Cachless Networking.)

[Samuli Suonpaa <suonpaa@iki.fi>]

Viktor Rosenfeld <rosenfel@informatik.hu-berlin.de> wrote:
> I suspect that the problem lies with scp.  On my local network I
> experience transfer rates of less than 200kB/s with scp because the
> server is an old Pentium 133 with not enough horse power.  With
> plain old rcp I get up to 6MB/s on a 100MB (half duplex?) link.

In that case I suggest you try blowfish cipher instead of 3des, which
seems to be Debian default for some reason. Blowfish is a _lot_ faster
than 3des, as this should demonstrate: (scp runs on my 400MHz laptop
and sshd on a 900MHz server, networks is 100Mbps with no additional
traffic.)

$ time scp -c 3des -q oberon:/var/www/testi.100M /dev/zero

real	1m28.652s
user	0m0.050s
sys	0m0.450s
$ time scp -c blowfish -q oberon:/var/www/testi.100M /dev/zero 

real	0m27.329s
user	0m0.070s
sys	0m0.390s

Nice difference, right?

When you have decided this is really what you want, it's time to edit
/etc/ssh/ssh_config to make blowfish the default cipher by adding
'Cipher blowfish' in part 'Host *'.

Suonpää...