Re: Network Slowdowns?

["Miguel Figueiredo Mascarenhas Sousa Filipe" <miguel.filipe@xxxxxxxxx>]

Hi,

On 12 Oct 2006 07:50:53 GMT, Oliver Fromme
<check+j70hk000rs05jd2r@xxxxxxxxxx> wrote:
> Matthew Dillon wrote:
>  > [...]
>  >    CPU overhead is a different beast entirely.   SSH has a lot of encryption
>  >    and decryption overhead... my transfers over localhost top out at
>  >    21.8 MBytes/sec on my test box.
>
> The good old ssh1 package had a "-c none" option which
> disabled encryption entirely.
>
> Unfortunately the OpenSSH folks removed it for "security
> reasons".  I have a patch that applies to FreeBSD's contrib
> version of openssh; I think it should be usable on DF, too
> (but I haven't tried).  The patch is very simple.
>
> http://www.secnetix.de/~olli/FreeBSD/openssh-cipher-none.patch
>
> It is useful in cases where the underlying transport already
> does encryption anyway (e.g. over IPSEC, an OpenVPN tunnel
> or whatever), or if you trust the network (e.g. your home
> LAN, of if it's a direct link between two boxes).  It makes
> a hell of a difference if at least one of the two machines
> has a slow CPU (or has a fast CPU but is loaded with other
> processes), and you're scp'ing large amounts of data.
> Of course you could use rcp, ftp or whatever, but the nice
> thing with "scp -c none" is that you can still benefit from
> all the other features of ssh, such as authentication via
> the authorized_keys file, shortcuts via .ssh/config, easy
> tunneling of X11 and other connections etc.

Just to add that the fastest ssh ciphers I've tested are:
blowfish-cbc
arcfour

that's the "performance tunning" I do on all ssh_configs..

googling will confirm this.. so did
a lot of big scp's linux/x86 <-> solaris 7/sparc back in the days, in
my university...
(over ethernet + IPoverATM (which sucks  btw.. :=) )



> Best regards
>    Oliver

best regards,

--
Miguel Sousa Filipe