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IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 3:53 pm
by Lincee
Hello,

It apears amahi has some problems, mostly with Windows clients.
When you assign a static IP to a computer, and that computer is not connected, DHCP gives that same IP out to other clients who connect.
thus resulting in an IP Conflict when the rightfull Client connects.

So far this has not happened on Linux, only on Windows.

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:03 pm
by ichat
Do not fix,

its a flaw where windows doesn't follow the 'proper' authentication sheme for dhcp 'this is probably because windows server automaticaly 'restricts' access to that IP lease 'thus expluding it from the 'scope'

the best way to fix would be to remove the 'make this a fixed ip' button from your dcpd pannel (if you want you should create a fixed-ip-wizzard, just outside your dynamic scope...

ie: 192.168.1. 10-50 for static ip's ) and 50 - 240 for dynamic...

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:06 pm
by rampage537
I have this issue, but shouldn't the DHCP reserve that IP address to that mac address and not give it out unless it matches that mac address?

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:08 pm
by cpg
can you guys provide details?

is the static ip in the 100-254 range?
maybe we should not allow static IP assignment in that range.

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:31 pm
by rampage537
I will give a little history, I use all static ip's in my house due to my firewall, for traffic shaping, content filtering, time access etc..
So I add the ip address and mac address per the static ip page on hda. If i bring a pc into that house that is not a on static it will grab first available address if i happen to start up a pc that has static already on I will often get a conflict. So it appears that for example i will have pc1 and pc2 with static ips. pc1 is on but pc2 is off, i will bring pc3 into the house (non static), I will start pc2 and get a ip address conflict cause pc3 has taken pc2 ip address.
Hope this makes sense.

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:37 pm
by cpg
yeah, but if you assigned static IP addresses below 100, you should never get these conflicts!

(if you do, it's a bug!)

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 4:49 pm
by rampage537
my static ip address are from 100 - 254 which is the range in which DHCP gives out address, I have never seen a address given out below that

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 5:02 pm
by cpg
you should assign IP addresses below 100 to avoid the conflict.

what i was suggesting is that perhaps the platform should not allow users assigning IPs in the DHCP range?

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 5:09 pm
by rampage537
That is probably a good idea, I guess i just assumes that the DHCP server would lock that ip address out if it was used as a static address

Re: IP conflicts with Amahi's DHCP

Posted: Sat Nov 28, 2009 5:30 pm
by bigfoot65
I have the same problem. I agree with cpg, we should not allow static IP addresses in the range of 100-254 which is reserved fro dhcp.

I have adjusted my static IPs accordingly, so now all machines are <100 and only those which use DHCP will be the 100-254. Seems like a simple plan to follow.