Manually release WAN DHCP lease?

[rhester72]

How is it done on AsusWRT/Merlin? I have a lease locked on FiOS via my RT-N66U and can't seem to get it to release, even when I disable the WAN. Any way to do so via GUI or CLI?

Rodney

 

[ColinTaylor]

You can't. The lease is controlled by your ISP's equipment not your router.

The only thing you can do is change (fake) the MAC address of your router (WAN > Internet Connection > MAC Address) and thereby trick your ISP into thinking a different piece of hardware had been connected to their network.

The only other possibility is to turn off your router for a few days and hope that its lease expires and is reassigned to another customer.

 

[rhester72]

I don't think that's accurate, because

a) when you release a lease on Windows, for instance, tcpdump absolutely shows an explicit release being broadcast, and

b) when swapping the Verizon-supplied Actiontec router for customer equipment (like, say, AsusWRT), explicitly releasing the lease on the WAN interface of the Actiontec is absolutely required to prevent lease-lock (which is, of course, precisely the same situation I'm now facing with my own router, except there is no explicit release mechanism that I can find, so thus I can't create the necessary broadcast packet to signal the ISP to let it go).

If it doesn't exist in AsusWRT, then it doesn't exist, and yes, I'll thus be forced to let the ISP time out (just changing the MAC doesn't work - Verizon tracks MACs, and will not grant a new lease to a different MAC until the previous has either been released or timed out). Bummer.

Rodney

 

[ColinTaylor]

I don't think that's accurate, because

I guess it's different here in the UK. Our main fibre provider issues very "sticky" IP addresses but at least they don't lock us down to individual MAC addresses (anymore).

Looking in the syslog of my router it looks like it issues a DHCP release when you reboot the router from the GUI:

Nov  4 18:15:54 FTP Server: daemon is stopped
Nov  4 18:15:54 Samba Server: smb daemon is stopped
Nov  4 18:15:56 dnsmasq[1283]: exiting on receipt of SIGTERM
[B]Nov  4 18:15:57 stop_wan(): perform DHCP release[/B]
Nov  4 18:15:57 dropbear[1271]: Exit (admin): Terminated by signal
Nov  4 18:15:57 kernel: Attempt to kill tasklet from interrupt
[B]Nov  4 18:15:57 stop_wan(): perform DHCP release[/B]
Nov  4 18:15:57 kernel: br0: port 1(vlan1) entering disabled state
Nov  4 18:15:57 kernel: vlan1: dev_set_promiscuity(master, 1)

 

[RMerlin]

Turning off WAN does send a lease release query. However it's possible that the ISP equipment doesn't do anything with it, so there isn't much you can do about it if they decide not to handle these. You will have to either fake a different MAC (and hope you aren't MAC-locked), or turn off the ISP equipment for 5-10 minutes (this is what cablemodem users usually have to do).