Viewing connected clients

Unanswered Question
Apr 15th, 2008


is there a way to view clients connected to the router?

I read on a Cisco PDF to enable ip finger - what does this do exactly?

I have an 857W wireless router and would like to see who is connecting to my network.

I know of the commands:

show ip nat translations - which give me all the forwarded port information


show users - however this only gives me clients connected to terminal applications

just as a sub question the output produced from show users is:

Line User Host(s) Idle Location

* 3 vty 1 admin idle 00:00:00

Interface User Mode Idle Peer Address

Vi2 PPPoATM 00:00:00

I don't understand the 2nd connection? After issuing the whois command on UNIX terminal the IP address is within my ISP range and Vi2 tells me that the interface is virtual2! Is this a potential security breach or is this normal?

I have this problem too.
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Hi, If you have CDP enabled the router will identify all Cisco devices connected to it " show cdp neighbor" or "show cdp neighbor detail". You can also run the show IP route and get the IP addresses of all directly interfaces with IP address and then do an nslookup from your pc command prompt.


bsmt#show cdp neighbor

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone

SEP000B46A7E3A8 Fas 6/24 108 H P IP Phone 7Port


SEP0019E8F49016 Fas 6/29 121 H P IP Phone 7Port


SEP000B46BDE695 Fas 2/10 136 H P IP Phone 7Port


SEP000B46D9CB63 Fas 2/24 114 H P IP Phone 7Port

1 Gig 1/1 107 R S I WS-C6506 Gig

3/4 Gig 1/2 140 R S I WS-C6509 Gig



kayasaman Tue, 04/15/2008 - 17:12

Thanks for that but is cdp a Cisco only command and how to enable it?

My guess is:# enable cdp

also show ip route doesn't give me the devices connected internally on my network, just the subnets eg.

as I would like to see devices on fe0-3 (fast ethernet) + D0 (wireless interface)

Do you know what the Vi2 interface is and why someone from outside is connected to it? It might just be my ISP but naturally I'm worried about security!

Istvan_Rabai Tue, 04/15/2008 - 19:04

Hi Kaya,

The "show ip arp" command will give you the ip addresses and mac-addresses of directly connected clients (directly means on the same layer 2 network), if they already provided their arp info to the router.

You can also ping the subnet to collect all the arp information like this:

Let's say you have a subnet /24.

Then "ping" will do the job for you.

You can enable cdp with the "cdp run" command globally or the "cdp enable" command on an interface.



kayasaman Wed, 04/16/2008 - 05:33

Thanks alot for that!!

show ip arp worked and was what I was looking for :-)

I did some background reading on cdp and it's only for Cisco devices and since I have only one, it doesn't show me any peers.

Also ping just came up with 5 dots, so it got a reply from the subnet but didn't tell me who was on there. Nevermind.

About my last query thuogh with the strange connection at Vi2. Could you shed some light on it?

I'm still new to Cisco IOS since I've only had my router for about a year, even though with the help of everyone here on this forum I built it myself but I'm no way an expert! - Thanks

Istvan_Rabai Wed, 04/16/2008 - 10:07

Hi Kaya,

You don't have to use I just gave you an example.

Instead, you should use the subnet broadcast address. It is dependent on your specific interface ip address (subnet) configurations.

The Vi2 is probably a kind of virtual interface, but you can check your interface types like this:

conf t

interface ?

It will list the interface types your device supports.



kayasaman Wed, 04/16/2008 - 10:32

Ok, the virtual interface Vi2 is bound to the ATM0 layer:

#show interface Vi2

which my guess is that it binds the Dialer0 and ATM0 interfaces together. The IP address I got therefore must be my ISP broadcast or gateway address.

I also managed to monitor the full parameters of the hardware by creating an SNMP server and monitoring through a program called Cacti which has a Cisco template to get interface, user, processor, and other data, running from a mySQL server.

It also identifies the Vi2 as a sub-interface from the ATM layer as the maximum bandwidth on the graph illustrated is upto 1Mb consistantly. Which makes sense as I have a 2Mb connection!

Ping I wasn't so lucky with I don't think I set it up correctly as the data given to me is minimal and no IP addresses stated even though I am on the correct subnet:

Something I guess I'll have to look into.

But thank you for all your help and assistance, sincerely if it wasn't for this forum and everybody in it contributing that I would not have learned as much about IOS as I know now or been able to even get my router up and running!


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