Distribution-independent way of testing if an interface's current IP was obtained via DHCP?

Question

Firstly, parsing configuration files isn't really correct. And not nearly distro-independent either.

My first idea was to search for running dhclient processes, but each distribution uses a different esoteric command line. Even the binary name itself varies. In Fedora, it's dhclient. In Ubuntu, it's dhclient3.

Is there something in /proc or /sys that indicates that an IP is dynamic?

Why exactly do you need this? What exactly are you trying to accomplish? — Juliano, Sep 10 '09 at 19:21
For the record: there are other DHCP clients one could be using (dhcpcd etc.) so looking for dhclient processes is really not a proper way to go about it. (But you probably suspected as much) — David Z, Sep 11 '09 at 00:15
Yes, for instance, pump is a very good alternative to dhclient. — bortzmeyer, Sep 14 '09 at 08:29
What distros out there use pump? Including non-Linux ones like *BSD and OpenSolaris. — JCCyC, Sep 16 '09 at 21:10

score 4 · Accepted Answer · answered Sep 10 '09 at 23:02

4

Have you grepped around in /var/lib/dhcp*/dh*lease* ?

On my Ubuntu system, as an example, /var/lib/dhcp3/dhclient-eth0.lease contains information about the current and recent leases.

answered Sep 10 '09 at 23:02

Dennis Williamson

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-1 because it is dhclient-specific and there are other DHCP clients. – bortzmeyer Sep 14 '09 at 08:30
The OP specified dhclient and dhclient3 in the question. – Dennis Williamson Sep 14 '09 at 13:34
So, how do pump and others store the leases? – JCCyC Sep 16 '09 at 21:07

score 0 · Answer 2 · answered Sep 10 '09 at 20:36

0

Check the DHCP server for a lease that matches the MAC address of the network card

answered Sep 10 '09 at 20:36

Mark Henderson

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... using dhcping utility. – hayalci Sep 10 '09 at 21:00
I only have access to the client machine. – JCCyC Sep 10 '09 at 21:34

Distribution-independent way of testing if an interface's current IP was obtained via DHCP?

2 Answers2