Introduction Of Linux Networking with examples.

Introduction Of Linux Networking 

To set the hostname temporarily 
[root@station9 ~]# hostname station9.example.com 
To view the hostname 
[root@station9 ~]# hostname station9.example.com 
Set hostname permanently 
[root@station9 ~]# vi /etc/sysconfig/network 
NETWORKING=yes 
HOSTNAME=station9.example.com 

:wq! 
Set ip address temporarily 
[root@station9 ~]# ifconfig eth0 192.168.0.9 netmask 255.255.255.0 View the interfaces. 
[root@station9 ~]# ifconfig 

eth0 Link encap:Ethernet  HWaddr 00:13:20:B7:1D:44
inet addr:192.168.0.9  Bcast:192.168.0.255 Mask:255.255.255.0 
inet6 addr: fe80::213:20ff:feb7:1d44/64 Scope:Link 
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 
RX packets:48153 errors:4 dropped:0 overruns:0 frame:4 
TX packets:21992 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 
RX bytes:39512670 (37.6 MiB)  TX bytes:1720318 (1.6 MiB) 

lo Link encap:Local Loopback
inet addr:127.0.0.1  Mask:255.0.0.0 
inet6 addr: ::1/128 Scope:Host 
UP LOOPBACK RUNNING  MTU:16436  Metric:1 
RX packets:1249 errors:0 dropped:0 overruns:0 frame:0 
TX packets:1249 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 
RX bytes:1285258 (1.2 MiB)  TX bytes:1285258 (1.2 MiB) 

Set permanent ip address 

[root@station9 ~]# netconfig 

Restart the service to activate the new ip address 
[root@station9 ~]# service network restart 
[root@station9 ~]# ifconfig 

eth0 Link encap:Ethernet  HWaddr 00:13:20:B7:1D:44
inet addr:192.168.0.9  Bcast:192.168.0.255 Mask:255.255.255.0 
inet6 addr: fe80::213:20ff:feb7:1d44/64 Scope:Link 
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 
RX packets:48173 errors:4 dropped:0 overruns:0 frame:4 
TX packets:22001 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 
RX bytes:39514528 (37.6 MiB)  TX bytes:1720864 (1.6 MiB) 

lo Link encap:Local Loopback
inet addr:127.0.0.1  Mask:255.0.0.0 
inet6 addr: ::1/128 Scope:Host 
UP LOOPBACK RUNNING  MTU:16436  Metric:1 
RX packets:1249 errors:0 dropped:0 overruns:0 frame:0 
TX packets:1249 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 
RX bytes:1285258 (1.2 MiB)  TX bytes:1285258 (1.2 MiB) 
[root@station9 ~]# netconfig --device eth0:1 

[root@station9 ~]# service network restart 
[root@station9 ~]# ifconfig 
eth0 Link encap:Ethernet  HWaddr 00:13:20:B7:1D:44
inet addr:192.168.0.9  Bcast:192.168.0.255 Mask:255.255.255.0 
inet6 addr: fe80::213:20ff:feb7:1d44/64 Scope:Link 
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 
RX packets:48749 errors:4 dropped:0 overruns:0 frame:4 
TX packets:22678 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 
RX bytes:39873471 (38.0 MiB)  TX bytes:1802196 (1.7 MiB) 

eth0:1 Link encap:Ethernet  HWaddr 00:13:20:B7:1D:44 
inet addr:192.168.1.9  Bcast:192.168.1.255 Mask:255.255.255.0 
UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1 RX packets:0 errors:0 dropped:0 overruns:0 frame:0 TX packets:0 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 
RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b) 

lo Link encap:Local Loopback
inet addr:127.0.0.1  Mask:255.0.0.0 
inet6 addr: ::1/128 Scope:Host 
UP LOOPBACK RUNNING  MTU:16436  Metric:1 
RX packets:1249 errors:0 dropped:0 overruns:0 frame:0 
TX packets:1249 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 
RX bytes:1285258 (1.2 MiB)  TX bytes:1285258 (1.2 MiB) 
To set or view the network parameters. 
[root@station9 ~]# ethtool eth0 
Settings for eth0: 
Supported ports: [ TP MII ] 
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supports auto-negotiation: Yes
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised auto-negotiation: Yes Speed: 100Mb/s 
Duplex: Full 
Port: MII 
PHYAD: 1 
Transceiver: internal 
Auto-negotiation: on 
Supports Wake-on: g 
Wake-on: g 
Current message level: 0x00000007 (7) Link detected: yes 

[root@station9 ~]# ifup eth0 
[root@station9 ~]# ifdown eth0 
[root@station9 ~]# cd /etc/sysconfig/network-scripts/ [root@station9 network-scripts]# ls 
ifcfg-eth0 ifdown-isdn   ifup-ipsec  ifup-routes
ifcfg-eth0:1 ifdown-post   ifup-ipv6   ifup-sit
ifcfg-lo ifdown-ppp ifup-ipx ifup-sl
ifdown ifdown-sit ifup-isdn   ifup-wireless
ifdown-aliases  ifdown-sl ifup-plip   init.ipv6-global
ifdown-ippp ifup ifup-plusb  network-functions
ifdown-ipsec ifup-aliases  ifup-post   network-functions-ipv6
ifdown-ipv6 ifup-ippp ifup-ppp
[root@station9 network-scripts]# cat ifcfg-eth0 
DEVICE=eth0 
ONBOOT=yes 
BOOTPROTO=static 
IPADDR=192.168.0.9 
NETMASK=255.255.255.0 
GATEWAY=192.168.0.254