ifconfig [<ifname> {inet | netmask | gateway} <address>]

[root@sylixos:/root]# help ifconfig       
show or set net interface parameter.
if there are no arguments, it will show all interface parameter
ifconfig -u (show all interface with 'IFF_UP' state)
ifconfig -r (show all interface with 'IFF_UP' & 'IFF_RUNNING' state)
set interface like following:
ifconfig en1 inet    192.168.0.3
ifconfig en1 netmask 255.255.255.0
ifconfig en1 gateway 192.168.0.1
ifconfig en1 dns 0   192.168.0.2
ifconfig dns 0       192.168.0.2
ifconfig [ifname] [{inet | netmask | gateway}] [address]
[root@sylixos:/root]# 

[root@sylixos:/root]# ifconfig en1 inet 10.4.0.92
[root@sylixos:/root]# ifconfig en1 netmask 255.255.0.0
[root@sylixos:/root]# ifconfig en1 gateway 10.4.0.1 
[root@sylixos:/root]# ifconfig en1                 
en1       Link encap: Ethernet HWaddr: 8c:ec:4b:44:d6:36
          Dev: rtl816x_0 Ifidx: 2 DHCP: D4 D6 Spd: 1000 Mbps
          inet addr: 10.4.0.92 netmask: 255.255.0.0
          gateway: 10.4.0.1 broadcast: 10.4.255.255
          inet6 addr: fe80::8eec:4bff:fe44:d636 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          collisions:0 txqueue:0 tcpaf:1 tcpwnd:65535
          RX ucast packets:3033 nucast packets:966360 dropped:0
          TX ucast packets:1903 nucast packets:16 dropped:0
          RX bytes:59494230 (56.7 MB)  TX bytes:117605 (114.8 KB)

[root@sylixos:/root]#