topic Re: DHCP in General Topics

DHCP

Denis — Tue, 21 Mar 2017 19:36:52 GMT

We've used Palo alto as DHCP server for all our wireless infrastructure, we notice that after one hour the IP has to expire and be release, however it keep the expired session on the DHCP and we have to manually clear out this from cli.

Once the pool is full no dhcp ip is released.

Anyone does know the issue?

Secondly can we automate the commands to run at specific time on Palo alto. E.g show session run every 8 hours

Thanks

Re: DHCP

Denis — Wed, 22 Mar 2017 04:10:01 GMT

Any hints please on how to troubleshoot this expired session

Re: DHCP

reaper — Wed, 22 Mar 2017 09:28:20 GMT

Hi Denis

Could you elaborate on your DHCP configuration (and PAN-OS version, some old version may have a bug)?

The default setting is an unlimited lease, this could cause your problem as leases will not be released

A lease may remain visible after the client has gone offline/off network, but the lease should be reused once the lease period has expired and a client requests an IP (unless the lease is unlimited)

you can automate an API call to fetch the info you like whenever you want:

/api/?type=op&cmd=<show><session><all></all></session></show>

here's a few helpful articles on the API:

Tips & Tricks: API configuration

Getting Started with the API

Re: DHCP

Denis — Wed, 22 Mar 2017 14:11:08 GMT

Hello,

Answers are below

(1) We currently have a lease time of 1 hr and no Reserve IP. We are running PAN OS 7.1.0.

(2) Can you please explain to me how can I schedule the task of clearing DHCP from the API.

Thanks.

Re: DHCP

reaper — Wed, 22 Mar 2017 14:28:24 GMT

I'd recommend upgrading your PAN-OS to a more recent version, 7.1.7 and 7.1.8 are currently recommended releases , in case the .0 release has a bug that locks the leases somehow. if that doesn't fix the issue you may need to get in touch with support.

for a scheduled API call you could use this command:

/api/?type=op&cmd=<clear><dhcp><lease><all></all></lease></dhcp></clear>

there's an API browser that allows you to explore all available commands:

https://<IP of your firewall>/API

Re: DHCP

BPry — Wed, 22 Mar 2017 14:28:51 GMT

1) Update away from 7.1.0 and install the latest supported 7.1.*. The version you are currently running was very early in the 7.1 life cycle and has some bugs you may be running into.

The api call would look something like https://firewall/api/?type=op&cmd=<clear><dhcp><lease><all><expired-only></expired-only></all></lease></dhcp></clear>&key=apikey

Replace firewall and apikey with whatever your local values should be.

If you were looking to schedule it you could easily do this with a powershell script. Keep in mind that the api call I have listed is only looking for expired leases across all interfaces, which sounds like what you need but you may need to modify to meet your needs.