unused IP address

[aksher]

hi all

how to view the unused IPs in the router.

thanks in adv

[shwetabohra_mca2005]

hi,

the first thing is what strategy u r using for ip assignment? & which O.S u r working with ?

if u r using dhcp & server is configured on linux than u can get list of assigned ip addresses in /var/lib/dhcp/dhcpd.leases

[aksher]

hi

i meant on a router.

[srego4]

YOu cant see unused IP's (unless you use NMS software and have discovered all devices in your network)

what you can do is see used IP addressess.. but a long process...

do a show arp on your router (arp entries timeout after 4 hrs by default if you have nto changed teh time.)

[dave.keith]

You can build a table of used IPs, then infer what IPs are unused from it. As mentioned, ARP entries time out, so you'll need a good way to collect and correlate the table periodically. Have a look at CatTools from www.kiwisyslog.com . It has the ability to poll Cisco router ARP tables and create an ongoing list of IP addresses seen, the corresponding MAC address, when a pair is first seen, and when last seen. Or if you are a Unix shop check out ARPwatch. Good luck.

Dave