Something you may want to consider is to put ACLs as far upstream as possible from your SBCs and only allow through what you need to the SBCs.  For example, apply a filter only permitting UDP 5060 and your RTP port range to your SBCs and then blocking everything else.  This is free and should stop a lot of common DDoS attacks before they ever get to your SBCs.  Even better if you can get your upstream ISP to apply the ACL.  DDoS attack traffic should be dropped as close to the source as possible.

 

-Rich

 

From: Mike Hammett <nanog@ics-il.net>
Date: Tuesday, September 21, 2021 at 4:39 PM
To: "Compton, Rich A" <Rich.Compton@charter.com>
Cc: NANOG list <nanog@nanog.org>
Subject: Re: [EXTERNAL] VoIP Provider DDoSes

 

CAUTION: The e-mail below is from an external source. Please exercise caution before opening attachments, clicking links, or following guidance.

*nods* We have a Metaswitch SBC.

 

So as long as the pipe isn't full, an SBC is the buffer one needs? If the pipe is filled, pump it through {insert DDoS mitigation service here}?

 

 



-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com

Midwest-IX
http://www.midwest-ix.com

 

From: "Rich A Compton" <Rich.Compton@charter.com>
To: "Mike Hammett" <nanog@ics-il.net>, "NANOG" <nanog@nanog.org>
Sent: Tuesday, September 21, 2021 4:59:06 PM
Subject: Re: [EXTERNAL] VoIP Provider DDoSes

Most of the larger DDoS mitigation appliances can block malformed SIP traffic and also can block volumetric/state exhaustion UDP floods.  A lot of VoIP companies have Session Border Controllers (SBCs) to protect public facing VoIP services.  SBCs are more application aware.  Kind of like a proxy based firewall just for VoIP.

 

-Rich

 

From: NANOG <nanog-bounces+rich.compton=charter.com@nanog.org> on behalf of Mike Hammett <nanog@ics-il.net>
Date: Tuesday, September 21, 2021 at 3:31 PM
To: NANOG list <nanog@nanog.org>
Subject: [EXTERNAL] VoIP Provider DDoSes

 

CAUTION: The e-mail below is from an external source. Please exercise caution before opening attachments, clicking links, or following guidance.

As many may know, a particular VoIP supplier is suffering a DDoS. https://twitter.com/voipms

 

Are your garden variety DDoS mitigation platforms or services equipped to handle DDoSes of VoIP services? What nuances does one have to be cognizant of? A WAF doesn't mean much to SIP, IAX2, RTP, etc.

 



-----
Mike Hammett
Intelligent Computing Solutions
http://www.ics-il.com

Midwest-IX
http://www.midwest-ix.com

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