Re: [Dots] Signal / Data / Alias / Filter Implementation

["Konda, Tirumaleswar Reddy" <[e-mail]>]

The source IP addresses and source ports used by the DDoS attacker could change, the type of attack itself could evolve or change from one attack type to another.
It was discussed in the WG that this kind of information are only hints and not mandatory to be conveyed by the DOTS client in the mitigation request.  https://tools.ietf.org/html/draft-ietf-dots-requirements-06 only discusses conveying the mitigation scope and not the source or type of the attack. However, DOTS signal channel draft allows vendor specific parameters and reserved key values in the range of 32768 to 65536 for vendor specific parameters, these hints can be conveyed as vendor-specific parameters to the DOTS server.

-Tiru

From: Dots [mailto:[e-mail]] On Behalf Of Jon Shallow
Sent: Wednesday, August 2, 2017 3:43 PM
To: [e-mail]
Subject: [Dots] Signal / Data / Alias / Filter Implementation

Hi There,

I am trying to get my mind around how to implement this and have some questions / statements.

Signal Channel

The Signal channel looks very like Destination RTBH with some extras (protocols / port) as everything is target-* based.  There is no concept of source-ip, source-port (to handle reflection attacks) etc. or dealing with fragmented packet, icmp types and rate-limiting.

The DOTS client may have the smarts to work out what are the problematic source-* etc. values (e.g. can generate smart BGP FlowSpec rules) are that will sensibly control the DDoS Attack.

It is possible to use a previously defined alias over the Data Channel as an alternative for a mitigation request, but this too has source-* etc. limitations.
I have not found a way of using a Filter defined over the Data Channel as a signal

Sending a signal will cause all traffic to stop (or rate-limit possibly if it also happens to match a filter) to the target IP on the ports in question -  DDoS attack is now effective unless the DOTS server elects (via DNS or BGP swing) to scrub that particular traffic (by controlling rates, Source IPs / Source Ports etc.).

Data Channel

Can be used to set up aliases for later use.  These again however appear to be target-* based, with no source-*, icmp type or fragmentation capabilities.

Can set up a Filter, which does include both source and destination IPs, but appears that it is acted on when pushed over the data channel, and cannot be send as a signal - appears to be in place more for black/white listing IPs than as a signal for mitigation, but does include rate-limiting

Questions

How do we handle Source-* information in a mitigation signal request?
How do we handle specific ICMP types  in a mitigation signal request?
How do we handle fragmentation  in a mitigation signal request?

Regards

Jon