Re: [OPSEC] I-D Action: draft-gont-opsec-ipv6-firewall-reqs-00.txt

["Smith, Donald" <[e-mail]>]

Just a nit initially.
"This document
   specifies a set of requirements for IPv6 firewalls, marked as
   "mandatory", "recommended", or "optional"."


That isn't the language we use.
In fact in terminology Mr Gont uses the right language.
"
3.  Terminology


   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119]."

This is hard very hard I don't know of a single v4 firewall that can do full proxies for all tcp applications.

REQ GEN-3:
      MUST support full-proxy for the TCP [RFC0793] connections (the
      handshake is validated on the firewall before reaching the target
      system).
I think what you want is proxies for common layer 7 protocols (like http, ftp etc...)
So maybe something like this:

REQ GEN-3:
      Should support full-proxy for common TCP [RFC0793] layer seven protocols.


However if what you really want is TCP three ways proxied that is a little different.
Would a tcp cookie implementation meet this requirement? Or do you want the three way done with the firewall then thrown away and you add the src to a whitelist for the next attempt or replay one side or do you want the fw to proxy the syn in, syn/ack out and ack back in? If so what is the benefit if it keeps all the state in two places now (host and firewall)?

Time outs are generally used mostly for UDP not TCP. I don't object to having a timeout ability on tcp connections too but their primary use is UDP today in v4.

REQ GEN-4:
      MUST be able to enforce timeouts on TCP connections based on
      specific protocols (e.g. enforce DNS timeout to a specific number
      of seconds, or FIN-WAIT, etc.).  In general, it MUST have
      different kind of timeout values and thresholds to be used to
      prevent idle established connections to saturate resources on both
      the device and the service that is defended.


So maybe "timeouts on UDP, TCP and other IP protocols" ...


This is sometimes referred to as policy routing.

REQ GEN-6:
      MUST be able to redirect specific traffic to a proxy server e.g.
      for HTTP/S protocols.

But by saying "redirect" in theory a FW could meet that requirement by just rewriting the MAC and replaying the packet. Not really routing a layer 2 redirect. Which did you mean or did you mean both?

REQ SPC-1 and 4 are the same.

It says here that we want to match icmpv6 errors to tcp and udp you should include "and other ipv6 protocols" and won't this bring on new icmp blind tcp reset issues?

REQ SPC-6:
      MUST be able to statefully match ICMPv6 errors to TCP [RFC0793],
      UDP [RFC0768], and ICMPv6 [RFC4443] communication instances.

Split tunneling is almost always a concern on the client side not on firewalls.

REQ VPN-5:
      MUST be able to disable or enable split-tunnelling feature on VPN
      as required.

I have never seen that applied to a firewall but can't say it couldn't be:)
In general you allow in a vpn remote access client and DON'T want them also connected directly to the internet as that punches a whole in your firewall (potentially anyways).


This:
   REQ VPN-6:
      MUST be able to work indifferently on IPv4 and IPv6, and also
      offer both protocol in dual-stack in the same VPN connection.

Should be this:
   REQ VPN-6:
      MUST be able to transit IPv4 and IPv6 packets providing full parity for services, and also
      offer both protocols in dual-stack in the same VPN connection.

I am thinking tunnel instead of connection but do not feel strongly about it.
The use of indifferently isn't technically wrong but isn't the common use of that word.


This is really ip stack specific attacks (not really os specific).
I have run non-native ip stacks on some OSes in the past (win3.1...)


REQ DoS-1:
      MUST be able to protect against OS-specific attacks: nuke, ping-
      of-death (NOTE: this list should be expanded, and references
      added).

And all of those pretty much died out. Having said that in there isn't bad.
Here are a few more of those ip stack attacks.

ICMP Fragments based attacks (this would include POD) and you include fragement based attacks in the next requirement.
Smurf Attack
Xmas Tree Attack
LAND Attack
Teardrop Attack



This one probably needs some expansion.

   REQ DoS-4:
      MUST be able to protect against TCP resource exhaustion attacks:
      zero-window attacks, SYN-floods, etc. (see e.g. [CPNI-TCP])


So for syn flooding do we want proxied tcp cookies, or simple tcp ratelimiting and do you expect grey, white and blacklisting to be done based on some form of authentication (completes the hand shake or gets the cookie right ...)?
Or can any or all methods be treated the same?


Wrong RFC :)
  REQ DoS-8:
      MUST be able to participate to a blackhole/sync hole routing
      infrastructure as per [RFC5635].

You probably want this one https://tools.ietf.org/rfc/rfc3882.txt as it talks about sinkholing (and it is sink hole not sync hole :)
The other one is about doing urpf with BHF and being able to do src based BHF.

Also we may need to define what "participate" means. I generally don't expect firewalls (FW) to talk bgp and BHF is generally done with BGP.


I will stop here for now to allow you to think about it and the next section is going to take more thought.














(coffee != sleep) & (!coffee == sleep)
 [e-mail]



From: OPSEC [[e-mail]] on behalf of Marco Ermini [[e-mail]]
Sent: Tuesday, February 18, 2014 7:57 AM
To: [e-mail]
Subject: [OPSEC] I-D Action: draft-gont-opsec-ipv6-firewall-reqs-00.txt


Hi everyone,

a new Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is about defining requirements for IPv6-capable Firewalls. You are welcome to have a look and contribute.

        Title           : Using Only Link-Local Addressing Inside an IPv6 Network
        Authors : F. Gont
                          M. Ermini
                          W. Liu
        Filename        : draft-gont-opsec-ipv6-firewall-reqs-00.txt
        Pages           : 12
        Date            : 2014-02-14

Abstract:

   While there are a large number of documents discussing IP and IPv6
   packet filtering, requirements for IPv6 firewalls have never been
   specified in the RFC series.  When it comes to IPv6, the more limited
   experience with the protocols, and reduced variety of products has
   made it rather difficult to specify what are reasonable features to
   be expected from an IPv6 firewall.  This has typically been a problem
   for network operators, who typically have to produce a "Request for
   Proposal" (from scratch) that describes such features.  This document
   specifies a set of requirements for IPv6 firewalls, marked as
   "mandatory", "recommended", or "optional".

The IETF datatracker status page for this draft is:

https://datatracker.ietf.org/doc/draft-gont-opsec-ipv6-firewall-reqs/

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/


Kind regards,

Marco Ermini - PhD CISSP CISA CEH ITIL MCP
Senior IT Security & Compliance Analyst | Compliance Europe
ResMed Germany Inc.
Geschäftsführer: Frank Rebbert, Eric Paffrath, Michael Taube
Sitz der Gesellschaft: München
Registergericht: München, HRB 156206

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