Full Disclosure mailing list archives
Re: Re: ICMP Destination Unreachable Port Unreachable
From: Barrie Dempster <barrie () reboot-robot net>
Date: Wed, 16 Aug 2006 12:33:13 +0100
<off list> On Tuesday 15 August 2006 21:45, Dude VanWinkle wrote:
Still, I cant seem to help but think there is something to this port 0 thingy http://www.networkpenetration.com/port0.html <snip> 3. Port 0 OS Fingerprinting --------------------------- As port 0 is reserverd for special use as stated in RFC 1700. Coupled with the fact that this port number is reassigned by the OS, no traffic should flow over the internet using this port. As the specifics are not clear different OS's have differnet ways of handling traffic using port 0 thus they can be fingerprinted.
Although the port 0 in this case is a red herring and irrelevant. Port 0 itself when used with TCP/UDP (not ICMP!) can actually be used on the Internet. A while back I modified netcat and my linux kernel so that it would allow usage of port 0 and was able to connect to a remote machine via TCP with that port and communicate fine. A few routers, especially those with firewalling abilities, such as those commonly used in SOHOs, reject the packets silently. In short port 0 is "reserved" most OSs use it to mean "random" (but this is not defined behaviour in an RFC, more of a tradition). If you do send out port 0 packets though, many routers will allow them. -- With Regards.. Barrie Dempster (zeedo) - Fortiter et Strenue - http://reboot-robot.net - "He who hingeth aboot, geteth hee-haw" Victor - Still Game
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Current thread:
- Re: Re: ICMP Destination Unreachable Port Unreachable, (continued)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Darren Bounds (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Dude VanWinkle (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Darren Bounds (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Scott Renna (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Valdis . Kletnieks (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Valdis . Kletnieks (Aug 15)
- Re: Re: ICMP Destination Unreachable Port Unreachable Barrie Dempster (Aug 16)
- Re: Re: ICMP Destination Unreachable Port Unreachable Valdis . Kletnieks (Aug 16)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 16)
- Re: Re: ICMP Destination Unreachable Port Unreachable Adriel T. Desautels (Aug 16)