DHCP in an hostel

Unanswered Question
Apr 23rd, 2009


we drive a switched network in a hostel.

Users change every 14 days.

How can I monitor the traffic for each user?

At the moment I use an ACL which logs to a syslog server. The problem with this is that the hosts get their addresses via dhcp, but which mac/interface get's which ip?

Syslog only logs the ip!

Using radius and 802.1x would be an overkill i think. Especially if each user have to configure it on his host.

The easiest thing would be if the dhcp addresses could be bound to an interface. i.e. Host on FastEathernet0/10 always gets as IP. Would that be possible? How?

Any further suggestions?

I have this problem too.
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John Blakley Thu, 04/23/2009 - 06:33

One thought would be (although maybe overkill and others may have better suggestions), create a vlan for each room that you have (if that's even feasible) and then assign addresses per vlan.

Room 1: (make your scope small)

Room 15:

Room 16:

Add the port that you want to what room:

Room 1:

int fa0/1

swit mode access

swit access vlan 1

Then your DHCP server will have a scope for that Room.

I've never been to a hostel, so I'm not sure how large they are which is why I said if this is even feasible. :)



Collin Clark Thu, 04/23/2009 - 06:35

What is the device that provides the gateway (ie router or firewall)? That device may be able to monitor the traffic. On the switch you can monitor who has what IP with the following commands.

<font size="2">CORE1#sh arp | inc</p><p>Internet 0 000c.5502.1e62 ARPA Vlan423</font>

This shows the IP to MAC address table. Once we have the MAC address we can find out what port they are on.

<font size="2">CORE1#show mac-address-table address 000c.5502.1e62</p><p></p><p>Mac Address Table</p><p>-------------------------------------------</p><p></p><p>Vlan Mac Address Type Ports</p><p>---- ----------- -------- -----</p><p>423 000c.5502.1e62 DYNAMIC <b>Fa0/27</b></p><p>Total Mac Addresses for this criterion: 1</p><p>CORE1#</font>

Hope that helps


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