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3

So i havn't done this with option 82, but your best bet would be to use classing in isc dhcpd. What you would do is setup a class like: class "userclass1" { match if substring(option agent.circuit-id, 2, 2) = "<your_id1>"; } class "userclass2" { match if substring(option agent.circuit-id, 2, 2) = "<your_id2>"; } Then in your pool ...


2

Ideally, you'd modify dhcpd to support address assignment based on Option82, equivalent to the "hardware" lines in host objects. I've done it with the OpenBSD dhcpd when I worked at an ISP, which has a simpler internal structure to isc-dhcpd. If you're not in a position to do that, then look at omapi(3) and omshell(1); you'd use OMAPI to dynamically create ...


2

At $former_employer, I modified the OpenBSD dhcpd to understand Option 82 and do address assignment directly on that. As a matter of policy, "if you're coming in on connection X, you have the address assigned to X and if you use a switch to connect multiple computers, that's your own problem", and then just direct assignment based on that. If you start ...


1

The only thing I can think of is to set the lease time excruciatingly low. What you're trying to do is essentially the exact opposite of what DHCP is intended to do, so don't expect there to be any simple and painless answers that actually work.


1

One option would be to encourage your user to release the DHCP lease before disconnecting. I realise this is a workaround, rather than a solution, and might require some user training before it is effective! On Windows, you can use the command "ipconfig /release" - although this requires elevated permissions, so a tool like CPAU might be useful. Under ...


1

Solution found: Setup switches to generate snmp traps on port down. On trap server catch them and call omshell script that deletes old lease. Not trivial, but also not impossible.


1

Maybe you can start from here: http://blog.nominet.org.uk/tech/2005/12/21/using-omapi-object-management-application-programming-interface/ Never used, but with a bit of scripting I think it could work. EDIT man omshell(1) would give some other examples


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You write that you added the new subnet at the end of the dhcpd.conf file. You need to add it to the shared-network, otherwise dhcpd will not consider these networks as alternatives.


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After reading man dhcpd.conf and playing around I've managed to achieve my goal by making the following ammendments to my dhcpd.networks file: subnet 172.20.111.0 netmask 255.255.255.0 { pool { option routers 172.20.111.1; max-lease-time 60; min-lease-time 30; range 172.20.111.10 172.20.111.20 ; deny members of ...


1

Just an addition to this old but still valid thread. It simplifies the subnet section but adds one line per fixed IP. class "FastIP"{ match pick-first-value (option agent.circuit-id); } class as before: class "IP-10.1.2.3" { match if option agent.circuit-id = "YourOp82Value"; } Add this for each Op82 value to exclude the fixed IP customer ...


1

Maybe you should take a look at dnsmasq. It can execute external and internal (LUA) scripts. The option --leasefile-ro should be what you are looking for. http://www.thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html



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