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Re: strange DHCP behaviour




On 2018-10-23 14:56, Tony van der Hoff wrote:
Hi, I havea laptop running fully up to date Stretch with NetworkManager,
set to use DH|Cp via wireless.

The DHCP server is another Stretch system, with the stanzas
host tony-lt {
	hardware ethernet 0c:60:76:6c:e6:6f;
	fixed-address 192.168.1.199;
	}
subnet 192.168.1.0 netmask 255.255.255.0
	{
        range 192.168.1.200 192.168.1.254;
        option routers 192.168.1.10;
	}

That MAC is correct for the laptop.

I an expecting to see 192.168.1.199 as the laptop address, but no, if a
gives:
wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
group default qlen 1000
    link/ether 0c:60:76:6c:e6:6f brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.253/24 brd 192.168.1.255 scope global dynamic wlan0
       valid_lft 479sec preferred_lft 479sec

Finally, the server shows:
Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:38 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:53 routerpi dhcpd[1068]: reuse_lease: lease age 15 (secs)
under 25% threshold, reply with unaltered, existing lease for 192.168.1.253 Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPREQUEST for 192.168.1.253 from
0c:60:76:6c:e6:6f (tony-lt) via eth0
Oct 23 14:23:53 routerpi dhcpd[1068]: DHCPACK on 192.168.1.253 to
0c:60:76:6c:e6:6f (tony-lt) via eth0

So, my question: why is the server handing out .253, when it is
configured to provide .199?
What is this 'reuse-lease' all about?

I've tried 'dhclient -r wlan 0; dhclient -v wlan0' on the laptop, to no
avail.

Any suggestions, please?

bearing in mind that I've no idea what I'm talking about is it possible that the laptop connected to the server and got a really long lease on .253 before you added

host tony-lt {
hardware ethernet 0c:60:76:6c:e6:6f;
 	fixed-address 192.168.1.199;
 	}
probably there is a command to flush leases ?

mick



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