[CentOS] SYD flood dropped on Sendmail (centos 4.x)

Chris Heiner cheiner at networkdesignsinc.net
Thu Nov 20 19:57:33 UTC 2008


11/20/2008 02:53:04.864 -       SYN flood attack dropped -
75.2.205.141, 48102 -   10.80.80.210, 110

11/20/2008 03:08:04.864 -       SYN flood attack dropped -
75.2.205.141, 64955, greatcooks.biz -   10.80.80.220, 110

11/20/2008 03:23:08.864 -       SYN flood attack dropped -
75.2.205.141, 43068, greatcooks.biz -   10.80.80.210, 110 

 
These are the statements from my Firewall saying that it was dropped.

-----Original Message-----
From: centos-bounces at centos.org [mailto:centos-bounces at centos.org] On Behalf
Of Kai Schaetzl
Sent: Thursday, November 20, 2008 11:31 AM
To: centos at centos.org
Subject: Re: [CentOS] SYD flood dropped on Sendmail (centos 4.x)

Chris Heiner wrote on Thu, 20 Nov 2008 08:48:50 -0800:

> My firewall seems to block an attack my Centos / Sendmail boxes on port
110.

port 110 is your POP server, probably dovecot.

> These servers require a reboot after each attack.

Because of what?

> My firewall says it's
> blocked?

I don't see this statement in your logs. How/where does it say this?

> Do I need to patch something on sendmail? Or is my firewall not
> doing its job (Sonicwall)? This is not the first time this has happened.

SYN floods are not unusual, even if it is not an attack. 
What or if you want to do something depends on your situation.



Kai

-- 
Kai Schätzl, Berlin, Germany
Get your web at Conactive Internet Services: http://www.conactive.com



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