Release ip

[skandshus]

So i have been looking & searching the web for a simple dhcp release command… I am unable to find it…

can it be true that devices with such a price tag really doesn’t have a simple and basic feature as release a wan ip… useful when swapping appliance without the need to contact the ISP or useful outside opening hours of the isp 

using a 1570 in this example 

[the_rock]

Maybe someone else can confirm, but I believe this is what you might be looking for:

https://community.checkpoint.com/t5/Security-Gateways/How-to-clear-DHCP-leases-on-Gaia-R80-10/td-p/2...

In R80.40, location is /var/lib/dhcpd/dhcpd.leases

[skandshus]

But will clearing there send a release command?

[PhoneBoy]

Go to Device > Network > Internet and disable the Internet connection.
This should release the IP.
That may not prevent the ISP from having the MAC/IP association cached, of course, so when you re-enable, you may get the same IP.
However, you can edit the Internet connection settings and change the WAN MAC in the Advanced tab, which should cause the ISP to allocate you a different IP.

[skandshus]

If the device sends a “release” command then the ISP accepts it and it’s possible to change equipment with a different Mac with no need of waiting a required lease time or contacting them to release… this is what I usually do when changing equipment… release the up manually, a lot faster..:)

I was just hoping to find something specific regarding this.. I also tried via cli but the TAB commands doesn’t show anything close to it

[PhoneBoy · Accepted solution]

It looks like that kills the interface and does NOT cause it to send a release message.
That said, I think I figured out how you can do it.
In expert mode, enter the following command:

dhclient -r -v -lf /var/dhclient.leases.WAN

This appears to cause the gateway to send a DHCP release message (tcpdump on the interface confirms this).
You will probably want to disable and re-enable the Internet interface in the UI after doing this.

[skandshus]

Thanks man.. I’ll get right on it and keep the command in my reminder..

[Harald_Hansen]

Maybe Check Point could fix this issue, one expects the DHCP client to release the IP address, especially on WAN, when the interface is disabled. Often the ISP allocates ONE IP address for each connection, which causes issues when replacing equipment.

[skandshus]

Exactly my point.. relying on an ISP releasing/deleting the lease should not be neccesary

[G_W_Albrecht]

dhclient syntax is available here: https://kb.isc.org/docs/isc-dhcp-41-manual-pages-dhclient