Re: [tram] Allow TURN to forward inbound connectivity checks without permission

Nils Ohlmeier <> Tue, 20 March 2018 12:30 UTC

Return-Path: <>
Received: from localhost (localhost []) by (Postfix) with ESMTP id 83CFC126D85 for <>; Tue, 20 Mar 2018 05:30:05 -0700 (PDT)
X-Virus-Scanned: amavisd-new at
X-Spam-Flag: NO
X-Spam-Score: -2
X-Spam-Status: No, score=-2 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HTML_MESSAGE=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Authentication-Results: (amavisd-new); dkim=pass (1024-bit key)
Received: from ([]) by localhost ( []) (amavisd-new, port 10024) with ESMTP id zTYvDbV8dsfE for <>; Tue, 20 Mar 2018 05:30:04 -0700 (PDT)
Received: from ( [IPv6:2a00:1450:400c:c0c::231]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by (Postfix) with ESMTPS id F3AE8124234 for <>; Tue, 20 Mar 2018 05:30:03 -0700 (PDT)
Received: by with SMTP id 80so407717wrb.2 for <>; Tue, 20 Mar 2018 05:30:03 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=google; h=from:message-id:mime-version:subject:date:in-reply-to:cc:to :references; bh=3FxR1l45YWltNOaZ8+TlrspeNpX6KqZIM29e+Awgua0=; b=DYkqJHODUni51N9kx75iRgZVepZ1jSabsy7ZY6lE0kciaiytHjnmOrwxMsdnSFZDMY HGEaRaVyhav+6b1miIC08ZExmq2rhWb9HU/8t5SwGxL5j57QMvzFZthlbRu7ElnuyxGp Ox3ymHPDNlW/BAIzzO+woQSh8lsx/EGPTyL1c=
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;; s=20161025; h=x-gm-message-state:from:message-id:mime-version:subject:date :in-reply-to:cc:to:references; bh=3FxR1l45YWltNOaZ8+TlrspeNpX6KqZIM29e+Awgua0=; b=cMFdmw4tnzm1MoPFnKd4D+RcKP4XVhU6NMVxkubiiUhjE5TQqpjFaO4AzQzonvIdYU S1fAXYTUKqoJhv166ew37bHWddq3G8/c/R12BTLFe96ewSAEd5Xav9L6vyaZdThhS5x6 8xnGUJk1wigDll6XbGwcLs4Cmruy0saLuCTYUB83I7Sd1jCRPfYUbOha2zhoDVUHUlLI Sx66dB6XUVDD6X7Jcw/WLoDrxnNUulDhgcb+4GSbR6eobyDje1RCjny+RRk0YEPI/0FK XQMEGZwycCfw0CAsPhDGNjA8BCwSaRksff5l7lT4VN6S/Kt1THsDLNgi/WrKKE6lEl0e yF1A==
X-Gm-Message-State: AElRT7GGHLVJ1MXCnyR+Zxp+Y/a3t9og/S+TmbBc0PUK2Fkk66enzkhr XzOk1K3AgQfLLmC9I+SQgnpKTQ==
X-Google-Smtp-Source: AG47ELsrIDofC9XAbi4RZO69tl+wbUXA0IWjBYc/ufQs+FppMRjvC92N98VJpmMy7pkzphMjiOpkBg==
X-Received: by with SMTP id p3mr12457437wrc.202.1521549002214; Tue, 20 Mar 2018 05:30:02 -0700 (PDT)
Received: from ?IPv6:2001:67c:1232:144:6d39:9314:376c:ca3b? ([2001:67c:1232:144:6d39:9314:376c:ca3b]) by with ESMTPSA id v22sm1388460wrd.43.2018. (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 20 Mar 2018 05:30:01 -0700 (PDT)
From: Nils Ohlmeier <>
Message-Id: <>
Content-Type: multipart/signed; boundary="Apple-Mail=_4ECEFD64-C2BA-4DB0-99D7-1F03A13A34B5"; protocol="application/pgp-signature"; micalg="pgp-sha512"
Mime-Version: 1.0 (Mac OS X Mail 11.2 \(3445.5.20\))
Date: Tue, 20 Mar 2018 12:30:00 +0000
In-Reply-To: <>
Cc: "Konda, Tirumaleswar Reddy" <>, Cullen Jennings <>, Eric Rescorla <>, "" <>, Brandon Williams <>
To: Simon Perreault <>
References: <> <> <> <> <> <>
X-Mailer: Apple Mail (2.3445.5.20)
Archived-At: <>
Subject: Re: [tram] Allow TURN to forward inbound connectivity checks without permission
X-Mailman-Version: 2.1.22
Precedence: list
List-Id: "Discussing the creation of a Turn Revised And Modernized \(TRAM\) WG, which goal is to consolidate the various initiatives to update TURN and STUN." <>
List-Unsubscribe: <>, <>
List-Archive: <>
List-Post: <>
List-Help: <>
List-Subscribe: <>, <>
X-List-Received-Date: Tue, 20 Mar 2018 12:30:05 -0000

> On Mar 20, 2018, at 12:17, Simon Perreault <> wrote:
> 2018-03-20 10:31 GMT+00:00 Konda, Tirumaleswar Reddy < <>>:
> the TURN client could be subjected to DDoS attack (e.g. spoofed STUN packets from attackers, client wastes cycles validating the message integrity, and could also be subjected to bandwidth-hogging attack).
> That would be new to TURN, but not new to the client: NAT pinholes, created with STUN or otherwise, expose the client similarly. So while this is certainly worth mentioning in the security considerations section, I don't see this as a blocker.
> I also can't think of a way that this could be exploited to mount any kind of practical attack against a specific target…

I guess you could divide this into three categories:

- the TURN client is an ICE agent, which needs to be prepared to handle any incoming traffic already any way
- the TURN client is not an ICE agent, but a STUN client, and as Simon pointed out needs to be prepared to receive traffic through the pin holes it created
- the TURN client is purely a TURN client and only ever expected to get traffic back from the TURN relay

I would assume the last scenario is not very common, but I don’t have any numbers to back that up.
I think Simon is right that it’s worth mentioning in the security considerations.

  Nils Ohlmeier