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Author Topic: Are 120 second DHCP leases on the WAN ok?  (Read 138 times)

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Offline ryanjaeb

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Are 120 second DHCP leases on the WAN ok?
« on: May 15, 2018, 10:18:40 pm »
Hi,

When looking at a firewall recently I noticed the WAN gateway issuing 120 second DHCP leases.  That means pfSense renews the lease every 60 seconds.  Is the renewal 100% seamless if the same IP is assigned?  I'm trying to figure out if it's something I should spend more time on or if it's ok to ignore.

TIA,
Ryan

Offline Derelict

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Re: Are 120 second DHCP leases on the WAN ok?
« Reply #1 on: May 16, 2018, 03:02:23 am »
Not a lot you can do about it if that is what your stupid ISP is doing.
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Offline kpa

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Re: Are 120 second DHCP leases on the WAN ok?
« Reply #2 on: May 16, 2018, 07:04:27 am »
Nope, the DCHP server is the king in this situation and you won't be able to use an expiring lease any longer than the server allows you to.

Offline JKnott

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Re: Are 120 second DHCP leases on the WAN ok?
« Reply #3 on: May 16, 2018, 07:52:40 am »
120 second lease?  That's going to generate a lot of traffic on the WAN side as all customers will be renewing every minute.  IIRC, the lease time from my ISP is 7 days, though it's been years since I checked.  Hours or days are typical for DHCP leases.
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Offline ryanjaeb

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Re: Are 120 second DHCP leases on the WAN ok?
« Reply #4 on: May 16, 2018, 03:06:42 pm »
120 second lease?  That's going to generate a lot of traffic on the WAN side as all customers will be renewing every minute.
The IPs are from an on-site, ISP controlled device using the 100.64.0.0/10 space.  The pfSense WAN is the only thing pulling an IP from it.  Other customers would have their own device.

I was mainly wondering if it's something worth pursuing with the ISP since it's unlikely they'll do anything about it.  It would take a lot of effort, so, if there aren't any significant drawbacks on the pfSense side, I'll probably end up ignoring it.

Offline Derelict

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Re: Are 120 second DHCP leases on the WAN ok?
« Reply #5 on: May 16, 2018, 03:33:03 pm »
If you don't "feel" it, there's not really anything to do.
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Use this diagram to describe your issue.
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