[libvirt-users] Would a DOS on dovecot running under a VM cause host to crash?

Hey All, I'm just wondering whether this is what caused my server to crash. Started last night in NZ land. Jun 20 19:22:11 elm dovecot: imap-login: Disconnected (tried to use disallowed plaintext auth): user=<>, rip=attackerip, lip=10.0.0.3, session=<0C8LzpDfZQDINsQC> occasionally get Jun 20 19:22:52 elm dovecot: imap-login: Disconnected (no auth attempts in 1 secs): user=<>, rip=attackerip, lip=10.0.0.3, session=<bHdz0JDfpwDINsQC> or in 0 secs last at Jun 20 19:26:24 elm dovecot: imap-login: Disconnected (tried to use disallowed plaintext auth): user=<>, rip=attackerip, lip=10.0.0.3, session=<1MUR3ZDfcwDINsQC> and a minute later the server lost contact to the world. When I checked a bit later, the underlying host machine (dovecot runs on a VM (KVM)) had been powered off. Now, here in NZ land, there was also a crazy storm last night, and lots of brown outs. There could potentially of been a surge that killed it, but the UPS was still running fine when I started it again. The "attack" lasted around 4 minutes, in which there was 1161 lines in the log for a single attacker ip, and no other similar logs previously. Would this be enough to kill not only the VM running dovecot, but the underlying host machine? All up to date with patches, running debian stable (wheezy). dovecot-core debian package version 1:2.1.7-7 dovecot version 2.1.7 I notice there is a version 2.2.3 out, but not in debian yet. Could this fix this issue? I don't particularly want to have it happen again :D. The host is running debian oldstable (squeeze), so could update more. libvirt0 debian package version 0.8.3-5+squeeze5 libvirt version 0.8.3 I notice there is a version 1.0.6 out (debian stable only has 0.9.12-11+deb7u1, which is 0.9.12), would either of these versions fix an issue like this? qemu-kvm debian package version 0.12.5+dfsg-5+squeeze10 kernel is 2.6.32-5-amd64 Any thoughts? Cheers, Hugh