FreeBSD renew ip command

The syntax is:

dhclient interface-name-here
dhclient [options] interface-name-here

The name of the interface must be specified on the command line. You must run this command as the root user.

How can I see the current IP address settings?

Type the following command:

ifconfig
ifconfig interface
ifconfig em0
ifconfig em0 | grep inet

Sample outputs:

How can I renew or release an IP in FreeBSD for em0 interface?

The syntax is:

$ sudo dhclient em0

#######################################
## OR first use 'su -' and then type ##
#######################################
# dhclient em0 

Sample outputs:

Other options in FreeBSD to renew dhcp IP address

You can also use the following command to renew dhcp IP address for em0:

service dhclient restart em0
 
## OR ##
/etc/rc.d/dhclient restart em0

Sample outputs:

Stopping dhclient.
Starting dhclient.
DHCPREQUEST on em0 to 255.255.255.255 port 67
DHCPACK from 192.168.1.254
bound to 192.168.1.142 -- renewal in 43200 seconds.

dhclient log file

In order to keep track of leases across system reboots and server restarts, dhclient keeps a list of leases it has been assigned in the /var/db/dhclient.leases.IFNAME file. IFNAME represents the network interface of the DHCP client (e.g., em0), one for each interface:

tail -f /var/db/dhclient.leases.em0

OR

less /var/db/dhclient.leases.em0

Sample outputs:

lease {
  interface "em0";
  fixed-address 192.168.1.142;
  next-server 192.168.1.254;
  option subnet-mask 255.255.255.0;
  option routers 192.168.1.254;
  option domain-name-servers 192.168.1.254;
  option host-name "freebsd10";
  option broadcast-address 192.168.1.255;
  option dhcp-lease-time 86400;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.1.254;
  option dhcp-renewal-time 43200;
  option dhcp-rebinding-time 75600;
  renew 0 2015/2/1 21:38:04;
  rebind 1 2015/2/2 06:38:04;
  expire 1 2015/2/2 09:38:04;
}
lease {
  interface "em0";
  fixed-address 192.168.1.142;
  next-server 192.168.1.254;
  option subnet-mask 255.255.255.0;
  option routers 192.168.1.254;
  option domain-name-servers 192.168.1.254;
  option host-name "freebsd10";
  option broadcast-address 192.168.1.255;
  option dhcp-lease-time 86400;
  option dhcp-message-type 5;
  option dhcp-server-identifier 192.168.1.254;
  option dhcp-renewal-time 43200;
  option dhcp-rebinding-time 75600;
  renew 0 2015/2/1 21:44:47;
  rebind 1 2015/2/2 06:44:47;
  expire 1 2015/2/2 09:44:47;
}

References

See dhclient man page for more info on a FreeBSD server:
$ man dhclient