[CentOS] Outbound traffic spike every 30 minutes

[Bowie Bailey]

On 12/3/2013 3:42 PM, diegors at gmail.com wrote:
 > >
 > > ------Mensaje original------ De: Bowie Bailey Remitente:
 > > centos-bounces at centos.org Para: CentOS mailing list Responder a:
 > > CentOS mailing list Asunto: [CentOS] Outbound traffic spike every 30
 > > minutes Enviado: 3 de dic de 2013 19:36
 > >
 > > Since Sunday morning, one of my CentOS servers has been generating a
 > >  small spike of outbound traffic every 30 minutes (X:00 and X:30).
 > > It's not enough traffic to really cause any notice except for the
 > > fact that it is a very regular pattern and it started abruptly at
 > > midnight Sunday.
 > >
 > > This server is used for mail (Courier-MTA), and DNS (Bind).  I cannot
 > >  find anything unusual in either of those logs.  I tried grepping
 > > through my firewall logs, but have been unable to find anything
 > > useful there either.  I don't see any cron jobs that would generate
 > > network traffic.
 > >
 > > Any suggestions how I can go about tracking this down?
 > >
 >
 > Is inbound or outbound?
 > What port?
 > tcp or udp?

It is outbound from my server to the Internet.  My traffic monitor does 
not give me any more detailed information, just a nice sawtooth graph 
showing the regular spikes.

TCP or UDP and the port is part of what I am trying to determine.

-- 
Bowie