j'ai un serveur DHCP qui attribue des IP selon les adresses MAC des clients. J'ai un client qui n'a pas de client DHCP installé (pas que je sache).

I have a DHCP server (on linux) which gives IP address depending of the MAD addresses of the clients (also on Linux). I have a client without any DHCP client (not that I'm aware of). But this client has the corresponding IP address as specified in the configuration of the DHCP server. When reading the server's logs (/var/log/syslog) and the client's (dmesg), I see nothing about DHCP or DHCP request.

On the client, I have a fresh install at every boot (image downloaded in RAM and booted), so I don't think it's an old lease (and it works after a few days, so it's probably definitly not that).

I'm curious to know how it works.

  • Perhaps the client has a static IP and the MAC reservation in the DHCP configuration just makes sure this IP is not leased to some other client? – jpe Jun 4 '15 at 8:38
  • No, no static IP anywhere. – Shan-x Jun 4 '15 at 8:39
  • The IP can also be assigned as a boot parameter to the kernel of the client, If it gets the address over DHCP, it should show in some DHCP server log. Make sure there is only one. – jpe Jun 4 '15 at 8:48
  • Using Wireshark, I can see a DHCP exchange. So there are two questions : - what is the DHCP client ? - why is there nothing in the logs (in the server or the client), whereas with dhclient there is some informations ? – Shan-x Jun 4 '15 at 8:55

The client machine may run some other type of dhcp client (it's unclear from the question if the system is plain stock linux or some customized one) and/or with a different logging configuration (in some other logfile or with a different logging level).

You could temporarily disable the dhcp server (with care as that would impact all other dhcp clients trying to boot during that interval) and try to boot the client - it should now fail to aquire an address, maybe re-trying repeatedly (thus it would be an actively running process) and maybe logging the errors, potentially helping you to pinpoint it.

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