linux > どのDHCPサーバーからIPを与えられたかを見る > grep -R "DHCPOFFER" /var/log/* | less -X

動作確認

CentOS 6.5

以下のコマンドでどのDHCPサーバーからIPを与えられたかを見ることができる。

http://xmodulo.com/how-to-find-ip-address-of-dhcp-server.html
のMethod Two

$grep -R "DHCPOFFER" /var/log/* | less -X

結果として以下のような表示が得られる

/var/log/messages:Aug 26 08:13:48 myPC dhclient[1800]: DHCPOFFER from 172.20.XX.18
/var/log/messages:Aug 26 15:39:01 myPC dhclient[1802]: DHCPOFFER from 172.20.XX.67
/var/log/messages:Aug 26 16:07:22 myPC dhclient[3034]: DHCPOFFER from 172.20.XX.18
/var/log/messages:Aug 26 16:08:26 myPC dhclient[3126]: No DHCPOFFERS received.
/var/log/messages:Aug 26 16:15:43 myPC dhclient[3126]: No DHCPOFFERS received.
/var/log/messages:Aug 26 16:17:21 myPC dhclient[1803]: DHCPOFFER from 172.20.XX.18
/var/log/messages:Aug 26 16:32:29 myPC dhclient[3164]: No DHCPOFFERS received.
/var/log/messages:Aug 26 16:33:06 myPC dhclient[3240]: DHCPOFFER from 172.20.XX.67
/var/log/messages:Aug 26 16:34:05 myPC dhclient[3335]: No DHCPOFFERS received.
/var/log/messages-20150806:May 18 12:38:15 myPC dhclient[1801]: DHCPOFFER from 172.20.XX.18
/var/log/messages-20150806:May 22 08:45:19 myPC dhclient[1802]: DHCPOFFER from 172.20.XX.18
...
/var/log/messages-20150806:Aug  6 10:32:35 myPC dhclient[1800]: DHCPOFFER from 172.20.XX.18
/var/log/messages-20150806:Aug  6 11:18:25 myPC dhclient[1800]: DHCPOFFER from 172.20.XX.18

上記の例では172.20.XX.18や172.20.XX.67がDHCPサーバー。
時々NO DHCPOFFERS received.という表示があるのはトラブル発生時。