dhcp getting wrong adress from server/uses cache?

ingemar

Hi!

I'm using Linksys router with DD-WRT firmware, but there's some sort of problem, and I think its my machine that's causing it. I have set up static leases for my computer, so that port forwarding and such can work easily, but I never seem to get the right ip adress! In the web interface for dd-wrt I can see all the active leases, and when they are bound to end, and my static is there, next to the new one, except for it having the wrong ip adress.

I've tried removing the faulty lease from the dd-wrt interface, and running dhclient (after removing some files from /var/lib/dhcp/), and that results in giving me the correct ip adress, but when using the standard way in gentoo (/etc/init.d/net.eth0 blah) which uses dhcpcd, it doesn't work. I keep getting the same ip, but it's not the desired one.. Could it be that dhcpcd uses some kind of cache it uses if it once have worked? I know dhclient has this feature.. Is there some file I can delete so that dhcpcd gets the correct adress?
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iBook G4 12" & AMD X2 4200+

darkphader · Veteran Joined: 09 May 2002 Posts: 1225 Location: Motown

I think the dhcp client asks for the ip address it had previously but if you have a lease tied to a mac address the server should nak the old address and present the new one. Suggest a remerge of the latest dhcp client and a double-check of the mac address for the reservation in your dhcp server settings.

Chris
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WYSIWYG - What You See Is What You Grep

ingemar · Posted: Wed Nov 14, 2007 9:00 pm Post subject:

The mac address specified in the router interface is of course correct. It exists two leases in the router with the exact same mac adress, one which is the one I want it to be, and the other, which isn't. And a reemerge doesn't help here..
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iBook G4 12" & AMD X2 4200+

cyrillic · Posted: Wed Nov 14, 2007 9:07 pm Post subject:

If dhclient works better than dhcpcd for you, then just put this in /etc/conf.d/net

UberLord · Posted: Wed Nov 14, 2007 11:44 pm Post subject:

dhcpcd-3.1 uses a DUID in the client ID instead of the MAC address.
This is RFC compliant as the Client ID could technically hold anything.

To change to a MAC address, use dhcpcd_eth0="-I ''" or emerge dhcpcd with the vram flag.
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MickKi · Veteran Joined: 08 Feb 2004 Posts: 1178

UberLord · Posted: Mon Nov 19, 2007 7:13 am Post subject:

vram = volatile ram.
Or in more simple terms, storage is nor permament.

This means we cannot store the DUID and use that in a client node identifier as it would change all the time.
Instead we revert to using the MAC address
_________________
Use dhcpcd for all your automated network configuration needs
Use dhcpcd-ui (GTK+/Qt) as your System Tray Network tool

darkphader · Veteran Joined: 09 May 2002 Posts: 1225 Location: Motown

UberLord · Posted: Mon Nov 19, 2007 9:14 pm Post subject:

Right field, but wrong value - your's looke like a standard MAC address.
Here's how one looks with a Client Node Identifer (IAID + DUID)

darkphader · Veteran Joined: 09 May 2002 Posts: 1225 Location: Motown

It's just the value that is there. I didn't make it up :)

Just wondered if I can use that value as the data in the 'option dhcp-client-identifier' parameter for dhcpd instead of the MAC address as the data to 'hardware ethernet'.

As in:

trailnut · n00b Joined: 16 Nov 2007 Posts: 21

I don't have one of those DD-WRT routers so I'll just throw this out here, if it doesn't apply sorry for the noise. I once had a router that allowed me to specify a static address that was inside my dynamic address range. This of course didn't work out very well and it silently ignored my static setting until I corrected it and moved it outside the range.

darkphader · Veteran Joined: 09 May 2002 Posts: 1225 Location: Motown

I'm getting timeouts from dhcpd:

MickKi · Veteran Joined: 08 Feb 2004 Posts: 1178

Is this new DUID thingy an IPv6 feature? Googling for it shows it referenced within an IPv6 context and I do not have IPv6 enabled in my kernel.
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Regards,
Mick

UberLord · Posted: Tue Nov 20, 2007 9:39 am Post subject:

UberLord · Posted: Tue Nov 20, 2007 9:41 am Post subject:

darkphader · Veteran Joined: 09 May 2002 Posts: 1225 Location: Motown