[69369] in North American Network Operators' Group
Re: BGP TTL check in 12.3(7)T
daemon@ATHENA.MIT.EDU (Pekka Savola)
Thu Apr 8 16:31:35 2004
Date: Thu, 8 Apr 2004 23:29:56 +0300 (EEST)
From: Pekka Savola <pekkas@netcore.fi>
To: Iljitsch van Beijnum <iljitsch@muada.com>
Cc: Blaine Christian <blaine.christian@mci.com>,
"<nanog@merit.edu>" <nanog@merit.edu>
In-Reply-To: <4A355820-8995-11D8-B512-000A95CD987A@muada.com>
Errors-To: owner-nanog-outgoing@merit.edu
On Thu, 8 Apr 2004, Iljitsch van Beijnum wrote:
> > You have an interesting point WRT the TTL 0. Perhaps if you receive
> > a packet with a TTL of 0 that is destined for yourself you should just
> > accept it?
>
> The interesting thing is that packets with a TTL of 0 wouldn't
> ordinarily be seen in the wild. A router won't forward a packet with a
> TTL of 1 (as this becomes 0 during the forwarding process) and a host
> that sends out packets with a TTL 0 can only expect to communicate on
> the local subnet. (So I guess doing all of this with TTL 0 rather than
> 255 would have been just as effective.)
Even sending packets with TTL=0 is invalid, so this is a moot point.
Or were you proposing modifying the sending and receiving
implementations and the IPv4/6 specifications?
From hosts requirements for v4, for example:
A host MUST NOT send a datagram with a Time-to-Live (TTL)
value of zero.
--
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings
