Dhcpd fixed-address leases

[Akey, Michael]

What is the appropriate way to see lease information on ISC dhcpd 4.2.2 for hosts defined with a fixed-address?  For example, say I have this config:

subnet 10.0.0.0 netmask 255.255.255.0 {
        option routers 10.0.0.1;
        option subnet-mask 255.255.255.0;
}

group {

host some.host.tld {
    hardware ethernet 00:11:22:33:44:55;
    fixed-address 10.0.0.2
}

[...]
}

I am able to see in my dhcpd logs the full transaction (discover/offer/request/ack) between the client and server.  However, when I look at the leases file or try to look for a lease object with the client's IP in omshell, the lease for that IP is not there.  For what it's worth, leases given to clients from pool declarations are present.  Should I be looking elsewhere, or is the dhcpd log the only place I can check to see if a client has requested a lease and given a fixed-address?

Thanks,

Mike Akey
Information Services
Oregon State University
541-737-4948

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[Gregory Sloop]

What is the appropriate way to see lease information on ISC dhcpd 4.2.2 for hosts defined with a fixed-address?  For example, say I have this config: subnet 10.0.0.0 netmask 255.255.255.0 {        option routers 10.0.0.1;        option subnet-mask 255.255.255.0; } group { host some.host.tld {    hardware ethernet 00:11:22:33:44:55;    fixed-address 10.0.0.2 } [...] } I am able to see in my dhcpd logs the full transaction (discover/offer/request/ack) between the client and server.  However, when I look at the leases file or try to look for a lease object with the client's IP in omshell, the lease for that IP is not there.  For what it's worth, leases given to clients from pool declarations are present.  Should I be looking elsewhere, or is the dhcpd log the only place I can check to see if a client has requested a lease and given a fixed-address?

>However, when I look at the leases file or try to look for a lease object with the client's IP in omshell, the lease for that IP is not there

That is normal/as-designed. Since everything needed to determine the lease given is already present in the config file, there's no need to put anything about these leases in the leases file. [There's no need to keep track of expiration, etc - it doesn't matter to the server.]

AFAIK, the only place you'll see record of it, is in the log files.

-Greg



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[Simon Hobson]

"Akey, Michael" <[hidden email]> wrote:

> I am able to see in my dhcpd logs the full transaction (discover/offer/request/ack) between the client and server.  However, when I look at the leases file or try to look for a lease object with the client's IP in omshell, the lease for that IP is not there.  For what it's worth, leases given to clients from pool declarations are present.  Should I be looking elsewhere, or is the dhcpd log the only place I can check to see if a client has requested a lease and given a fixed-address?

As Greg says, for fixed-address clients, no lease is stored. If you need to see a lease for it, then you may find reserved leases a viable alternative. These are normal dynamic leases, except that by adding the "reserved" keyword to the lease (AFAIK you can either edit the leases file or use OMAPI/OMSHELL) it is reserved exclusively for the one client. In other words, a reserved lease will never be reallocated even if it's long since expired.



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