[Info-vax] SSH on VAX - performance impact of break in attempts

[urbancamo]

Good morning,

I have a VAX running Multinet V5.3 under a hobbyist license which has
an SSH server running to allow access for selected remote users. I've
been experiencing a number of break in attempts lately, generally
lasting for several hours each. Each attempt causes the SSH server to
utilise 100% CPU for about 20 seconds (on a VAXstation 4000/90) - this
is having a negative impact for users on overall system performance. I
am using the SSH2 server.

I have attempted a number of strategies to reduce this impact:

1. I have defined an AllowUsers list so only named users are allowed.
2. I have set AuthInteractiveFailureTimeout to 30 so that there is a
30 second delay between login attempts from the same host/session.
3. I have set RequiredAuthentications to publickey,password so that
both a password and a valid public key are required.

Unfortunately none of these strategies reduce the length of 100% CPU
utilisation for failed login attempts.

If anyone has any suggestions that would be great.

Many thanks, Mark.