
The dhclient command is used to obtain, renew, and release a clients IP address, subnet mask, default gateway, and DNS servers from a DHCP server.
The ps command can be used to determine if your system is using init or systemd. If PID 1 is init, then you will use the service command. If PID 1 is systemd, then you will use the systemctl command.
If your system is using systemd, use the systemctl command to stop and disable avahi-daemon.
systemctl disable avahi-daemon
systemctl stop avahi-daemon
systemctl status avahi-daemon
If your system is using init, use the chkconfig and service commands to stop and disable avahi-daemon.
chkconfig avahi-daemon off
service avahi-daemon stop
service avahi-daemon status
Obtain IP address
Let's say eth0 does not have an IP address.
~]# ip address
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 70:f1:a1:8c:ca:2f brd ff:ff:ff:ff:ff:ff
The dhclient command can be used to obtain the IP configuration information from the DHCP server.
~]# sudo dhclient eth0
After running the dhclient command, eth0 should have IP address information.
~]# ip address
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 70:f1:a1:8c:ca:2f brd ff:ff:ff:ff:ff:ff
inet 192.168.0.164/24 brd 192.168.0.255 scope global wlan0
valid_lft forever preferred_lft forever
Dhclient.leases
When dhclient leases IP confirmation information from a DHCP server, the information will be written to the dhclient.leases or dhclient6.leases files. These files are located in the /var/lib/dhclient or /var/lib/dhcp directory. The content of these files will list the IP configuration information.
~]# cat /var/lib/dhcp/dhclient.lease
lease {
interface "wlan0";
fixed-address 192.168.0.164;
option subnet-mask 255.255.255.0;
option routers 192.168.0.1;
option dhcp-lease-time 43200;
option dhcp-message-type 5;
option domain-name-servers 192.168.0.6;
option dhcp-server-identifier 192.168.0.4;
option domain-name "software.eng.apl";
renew 6 2017/04/15 15:23:48;
rebind 6 2017/04/15 15:23:48;
expire 6 2017/04/15 15:23:48;
}
Release IP address
The -r option can be used to release the IP configuration information from the interface. This will assume IPv4.
~]# sudo dhclient -r eth0
The -6 option can be used to releases an IPv6 address from the interface.
~]# sudo dhclient -6 -r eth0
After running the dhclient command with the -r option, eth0 should no longer have IP address information.
~]# ip address
eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether 70:f1:a1:8c:ca:2f brd ff:ff:ff:ff:ff:ff
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