Slow connection performance with ssh2

Gregory Leblanc gleblanc at linuxweasel.com
Mon Nov 5 01:05:19 EST 2001


On Sun, 2001-11-04 at 12:00, Gert Doering wrote:
> Hi,
> 
> On Sun, Nov 04, 2001 at 03:18:00PM +0100, Robert Dahlem wrote:
> > SSH2_MSG_KEX_DH_GEX_REQUEST sent         SSH2_MSG_KEX_DH_GEX_REQUEST received
> > expecting SSH2_MSG_KEX_DH_GEX_GROUP      SSH2_MSG_KEX_DH_GEX_GROUP sent
> > ********* 3.330 seconds                  ********* 3.39 seconds
> > dh_gen_key: priv key bits set: 134/256   dh_gen_key: priv_key bits set: 126/256
> 
> I have noticed the same - it hangs at these points for a while:
> 
> debug: Sending SSH2_MSG_KEX_DH_GEX_REQUEST.
> debug: Wait SSH2_MSG_KEX_DH_GEX_GROUP.
> debug: Got SSH2_MSG_KEX_DH_GEX_GROUP.
> <pause, loooong>
> debug: bits set: 1008/2049
> debug: Sending SSH2_MSG_KEX_DH_GEX_INIT.
> debug: Wait SSH2_MSG_KEX_DH_GEX_REPLY.
> <2nd pause, shorter>
> debug: Got SSH2_MSG_KEXDH_REPLY.
> 
> As my hardware is slower (Sparc LX, NetBSD, 50 MHz CPU) it takes more 
> than 2 minutes (!!), which are spent on CPU cycles in ssh and sshd - running
> with 95% CPU... - the overall CPU time used by sshd for a successful
> connect is about 2:50 minutes

Older SPARCs in general are bloody slow at encryption operations.  Try
upgrading to 2.9.9p2, and make sure that you're -not- using DSA, as
that's REALLY REALLY slow.
	Greg




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