Re: Dropbear SSH server Denial of Service

[Damien Miller <djm () mindrot org>]

On Fri, 10 Mar 2006, Matt Johnston wrote:

> Dropbear 0.48 mitigates this issue by having a per-IP limit
> as well as a global limit - this will at least prevent an
> IP-deprived attacker from denying service.
>
> It's worth noting that various other network services (such
> as netkit-inetd and OpenSSH) have the same design issues, at
> least in default configurations.

OpenSSH has had connection-flood DoS mitigation since 2000, in the 
form of random early drop of connections so legitimate users have a
probabalistic change of getting in. See the "MaxStartups" documentation
in sshd_config(5)

-d