Wednesday, May 20, 2009

Disable DHCP on a Cisco router or wireless access point

If you already have a DHCP server setup, there's no need to leave DHCP enabled on your Cisco router or WAP. It can also lead to other issues since the DHCP scopes and settings may differ, or you may start getting IP address conflicts. To disable the DHCP service:

1. Login to your Cisco router through SSH or Telnet
2. Enter Enable mode by using the en command. Enter the enable password if prompted
3. Enter configuration mode by typing conf t. That will get you to the configuration terminal
4. Type no service dhcp and press Enter. This will disable the DHCP service
5. Type end and press Enter
6. Type wr and press Enter. This will write your configuration changes to memory
7. Type exit and press Enter to leave the SSH or Telnet session

That's it. Now as long as your Cisco router is RFC1542 enabled, it will pass the DHCP requests to your DHCP server rather than handing out IP addresses itself.

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