[Dovecot] Would attempting plaintext auth repeatably cause a DOS and server to crash?

[Daniel Reinhardt]

I doubt that the 1161 log lines would cause the VM to crash.  It would
potentially cause the logging directory to fill up if you have a small /var
partition where the logs are kept and at that point it could potentially
freeze the VM, but not cause the host to crash.  I think your issue
revolves around the storms.  I also do not consider a 1161 log lines a
DoS.  If it takes 1161 lines of failure entries to deny service to your
server, then I would take a look at your setup.


On Fri, Jun 21, 2013 at 3:37 AM, Steffen Kaiser <
skdovecot at smail.inf.fh-brs.de> wrote:

> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On Fri, 21 Jun 2013, Hugh Davenport wrote:
>
>  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.
>>
>
> I cannot believe that a DoS of a guest VM causes the host machine to power
> off.
>
> - -- Steffen Kaiser
> -----BEGIN PGP SIGNATURE-----
> Version: GnuPG v1.4.11 (GNU/Linux)
>
> iQEVAwUBUcQCtl3r2wJMiz2NAQIufg**gAr5cbKwdTNBIC7+RqhXAMN4N0C+**964Bn0
> Nlj5bxgZOo1KxqhRbxkvuiH5BRs7kQ**/**o7Nr7O7xbO0YPbMt3lQTGnsbKdPgbK**v7a
> ojqbSsXCxHOZkzNRkW4pDRty8JMEGQ**0oSMBzRbVlMrS+9g+**5FtFkPmOHFnHfEJ39
> a91+**O34fa42TbQgjmVPMWZQr6Oy6JtDcy7**fhdzI8d5iPv5KI/rL81hSTr9bm7spk
> ma4rBOKZfkd66In8BkqJPNRMIgP7ky**hGrrLxgOr4HlcgkxAm4+zo/**eBAGQruM4u+
> RcNa3IFTf0BpFrqL43XXS8ViqS5z16**L4a/MPnHFZc8rzLKldolI97Q==
> =bCZ0
> -----END PGP SIGNATURE-----
>



-- 
Daniel Reinhardt
cryptodan at cryptodan.net
http://www.cryptodan.net
301-875-7018(c)
410-455-0488(h)