Mailing List Archive

*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

----- Original Message -----

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
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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
The contents of this e-mail message and
any attachments are intended solely for the
addressee(s) and may contain confidential
and/or legally privileged information. If you
are not the intended recipient of this message
or if this message has been addressed to you
in error, please immediately alert the sender
by reply e-mail and then delete this message
and any attachments. If you are not the
intended recipient, you are notified that
any use, dissemination, distribution, copying,
or storage of this message or any attachment
is strictly prohibited.

E-MAIL CONFIDENTIALITY NOTICE:
The contents of this e-mail message and any attachments are intended solely for the addressee(s) and may contain confidential and/or legally privileged information. If you are not the intended recipient of this message or if this message has been addressed to you in error, please immediately alert the sender by reply e-mail and then delete this message and any attachments. If you are not the intended recipient, you are notified that any use, dissemination, distribution, copying, or storage of this message or any attachment is strictly prohibited.

Hi

>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.

Yes Attacks on voip have become more prevalent unfortunately.
Another thing to consider is blocking fragments , which have been a major factor in the attacks I have seen in sip.
But to do this you need to make sure that you are not exceeding mtu length in Invites, or block fragments only from untrusted IPs.

Brian