Finding IPs of All Devices on Single VLAN?

[Madman_Lorenzo]

Evening all.

 

Undergoing some changes in the setup here and our current CCTV system uses an old switch-to-switch VLAN, with no records of the cameras installed.

 

Is there any command anyone knows of that a switch could run that'd return all the IP addresses (also MAC addresses would be nice) of all devices on a particular VLAN? Something in LLDP I'm thinking?

 

Bit out of my depth on that one but if anyone does know that'd be splendid.

 

Thanks all.

Edited July 13, 2022 by Madman_Lorenzo

[mitchell1981]

Try this utility: https://www.advanced-ip-scanner.com/

 

Just ensure your pc (or a second adapter on you pc) is on the vlan you want to scan.

[mavhc]

Can you see from the arp cache on the computer running the central controller? Doesn't the software itself have a list? If you know the ip range it's easy enough

[dmj]

nmap -sn x.x.x.x/yy

 

https://nmap.org/download.html

[dmj]

Can you see from the arp cache on the computer running the central controller?

 

good point, once something has connected just query the arp cache for the mac address

[FN-GM]

What switches are you running?

 

The following might be useful (Cisco command).

 

Show Mac Address-Table

 

The problem with LLDP it requires the end device to support it and have it enabled.

[psydii]

Also Wireshark - I've found several errant devices with static IPs on the wrong VLAN/Subnet by just looking for unexpected IPs* in a Wireshark capture.

 

 

*by filtering out the expected.

[FN-GM]

Also Wireshark - I've found several errant devices with static IPs on the wrong VLAN/Subnet by just looking for unexpected IPs* in a Wireshark capture.

 

 

*by filtering out the expected.

 

Good shout!

[Madman_Lorenzo]

First of all you're all great, thanks much for coming to my aid here.

 

#show mac address-table got me at least the MAC addresses in the end, from there I can determine the IPs if I need.

 

Very grateful.

[tosh74]

show arp

[Davit2005]

For Aruba/HP, On a layer 3 switch where the vlan is routed i.e. it's default gateway.

 

All arp entries

sh arp

 

Search for a IP address from a known mac address

sh arp | include [MAC-ADDRESS]

 

Search for a MAC address from a known IP address

sh arp | include [iP ADDRESS]

 

Search by specific vlan

sh arp vlan [VLAN ID]

 

From a windows desktop if you know the IP you can ping then list the arp table by running command arp -a very handy if you have a rogue DHCP server and are running on a effected client

Edited July 14, 2022 by Davit2005

[avillemcp]

helpful thread