On 2007-10-31, Timothy Murphy <tim@birdsnest.maths.tcd.ie> wrote: > Is there an easy way to determine all the machines > (or other devices) on a LAN? Define "determine", "machines (or other devices)", and "LAN". Let's start backwards: officially, the LAN is anything on ethernet that doesn't go through a router. But some sites have more than one router, and some people want to know about all the machines at their site. Do you want to know about machines with a MAC or IP, or *all* devices? It might not be so easy to determine whether (or where) there are hubs or switches, nor to determine whether there's a machine connected but it's not powered on (or its interface is down). What do you want to know about these machines? IP, MAC, hostname, OS, other? Modulo the answers to the above questions, one easy way to report some machine information is by using nmap on your subnet (if you have permission to do so). You can nmap anything with an IP address, so you can cross a router if needed; it's real-time, so if a machine is off at the time you nmap, you won't find it. --keith -- kkeller-usenet@wombat.san-francisco.ca.us (try just my userid to email me) AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt see X- headers for PGP signature information

Timothy Murphy <tim@birdsnest.maths.tcd.ie> writes: >Is there an easy way to determine all the machines >(or other devices) on a LAN? No, not for sure. arp -a will list the ip and mac for all the machines yours has talked to recently. If the machine does not respond to any requests on any port or go out, then it can sit there silently listening with non-the-wiser.

On 2007-11-02, Timothy Murphy <tim@birdsnest.maths.tcd.ie> wrote: > > The trouble with nmap is that there are a billion options, > and it is not at all clear which to choose. There are a bunch of examples in the manpage. --keith -- kkeller-usenet@wombat.san-francisco.ca.us (try just my userid to email me) AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt see X- headers for PGP signature information

On 2007-11-02, Timothy Murphy <tim@birdsnest.maths.tcd.ie> wrote: > Agreed. > I did in fact look (briefly) at these, > but all seemed far too complicated for my modest needs. > The man page for nmap is an example, in my eyes, > of too much information being almost as bad as no information. There's also http://www.nmap-tutorial.com/ . --keith -- kkeller-usenet@wombat.san-francisco.ca.us (try just my userid to email me) AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt see X- headers for PGP signature information

On 2007-11-02, Timothy Murphy <tim@birdsnest.maths.tcd.ie> wrote: > Keith Keller wrote: >> >> There's also http://www.nmap-tutorial.com/ . > > there really should be a pointer to it in "man nmap". You should make that suggestion to the nmap maintainer, since a) he doesn't read this group, and b) he doesn't maintain the tutorial site. He may not even want to point people there, but it's his decision to make, not any of ours. --keith -- kkeller-usenet@wombat.san-francisco.ca.us (try just my userid to email me) AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt see X- headers for PGP signature information