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ajd617
Posts: 2
Registered: ‎07-08-2007

Can't delete DHCP Clients

[ Edited ]
Hello,
I have a Linksys BEFSR81 V3 with various PCs (Win2k, XP, Vista) connected.  I set up the Linksys to allow 10 IPs two of which are used by my kid's friends when they bring their laptops over for a gaming session.  Once they leave, I cannot delete their client leases even though the machines are no longer connected to the network.  Any help would be appreciated.


Message Edited by ajd617 on 07-08-2007 06:58 PM
toomanydonuts
Posts: 6,365
Registered: ‎09-16-2006

Re: Can't delete DHCP Clients

[ Edited ]
Don't the DHCP leases just expire after a day or so?
The friends cannot use that lease unless they are wired to your router through a LAN port.  The lease will not do them any good if they try to access your network through the Internet.
 
So why do you want to delete them?  I just ignore them.


Message Edited by toomanydonuts on 07-09-2007 08:10 AM
ajd617
Posts: 2
Registered: ‎07-08-2007

Re: Can't delete DHCP Clients

That's the problem.  They do not expire ever.  So if I hook up a new machine that I am building or testing I cannot get a lease from the router unless I manually increase the number of IPs.  So the number keeps going up and up.  I dropped the IP count a couple (since the PCs happened to get the two highest numbers but still less than I need) and they went away.  However, as soon as I upped the IP count to a higher number, the leases came back again even though the two PCs are in different states.  There is a feature that allows you to delete the IP, just isn't working and I'm wondering why.
Thanks,
toomanydonuts
Posts: 6,365
Registered: ‎09-16-2006

Re: Can't delete DHCP Clients

[ Edited ]
It looks like if you go to the "Status" tab, "Local Network" subtab, then you can click on "DHCP client table" to display the list of active DHCP clients.  Then on this page where they are displayed, there should be a "Refresh" button, which should update the list.  Does that button work?  If not, what version of the firmware are you using?
 
Also, in the router, make sure the "client lease time" is set to zero, which means "one day".  This should force the client leases to expire after a day.
 
Also, setting the DHCP clients to 10 is rarely needed.  In most cases, home users should leave their "Maximum number of DHCP users" set to 50.  There is no security benefit to limiting your DHCP addresses to 10.  The security of a home wired network comes from the physical security of your network, that is, from the fact that you only let "trusted" people connect a wire to your network.  Unless you have some very unusual circumstances to justify having just 10 DHCP users, I would suggest you reset it to 50.  Remember that the "DHCP lease" is only good for those who can connect a wire to your LAN (the numbered ports).  It does not let anyone connect through your WAN (Internet) port.  So once people leave your home, their DHCP lease doesn't work for them.


Message Edited by toomanydonuts on 07-09-2007 03:03 PM
kae
kae
Posts: 8
Registered: ‎10-05-2007

Re: Can't delete DHCP Clients

I have a similar problem on my BEFSR81 version 3.0 running Firmware Version: 2.51.3.

Half of my 14 clients have no Hostname. All 14 MAC addresses are unique, but when I try to delete an entry, I get the error message:

Error 404 Not Found
Bad request or resource not found

I currently have 192.168.1.100 thru 116 (missing 101, 108, 109) the refresh button appears to work except I never see a change.

I would think that restarting the router would reset the dhcp client list.
toomanydonuts
Posts: 6,365
Registered: ‎09-16-2006

Re: Can't delete DHCP Clients

[ Edited ]
to kae  ---
 
Do you have your DHCP set to 50 users?
 
Why do you want to delete your DHCP list?  Why can't you just ignore it?  I suspect your router is just trying to give the same IP address to the same MAC address whenever possible.  The only way to do this is for your router to keep a list.


Message Edited by toomanydonuts on 10-06-2007 04:16 AM
kae
kae
Posts: 8
Registered: ‎10-05-2007

Re: Can't delete DHCP Clients

Yes, I have DHCP clients set to the default 50. Just about everything on the router is set to the default values except the password and I named the router (not that the name seems to buy me anything, since I can't seem to access the router by name). I agree with you that reducing the max DHCP clients to a lower number doesn't guarantee much. I don't have the RFC in front of me, but IIRC each machine would have to release it's IP properly or you might run out of addresses unless a Request from the same MAC is interpreted by the server as an extended lease.

I don't have any reason to want to delete them and I usually do just ignore them, but the button was there and I just tried to use it. The delete button doesn't seem to work and throws an error. It would be nice to have more information in the Client table (like expiration time)

Does the blank "hostname" mean that the client released that IP?

When I was investigating, I found that some of those blank IP addresses were still being used by the client (I used the MAC address to find out who owned the IP). I say some because I didn't make it through all 20 and some odd hosts (I think the count is 23 hosts).

Actually, I'm fine with the router keeping the old entries as a way to try to give back a previously used IP address. I actually like it when machines stay at an IP address (without me having to manage a static host table across so many machines).