Linux常用命令（6）网络通信命令

1、命令名称：write

　　执行权限：所有用户

　　功能描述：向另外一个用户发送信息，以CTRL+D作为结束

　　语法：write <用户名>

root向luxh用户发送信息

[root@localhost ~]# write luxh
write: luxh is logged in more than once; writing to pts/1
hello,luxh,i am root

用户luxh接收到的信息为
[luxh@localhost ~]$ 
Message from luxh@localhost.localdomain (as root) on pts/0 at 05:17 ...
hello,luxh,i am root

　　root用户向luxh用户发送信息，luxh用户必须已经登陆，否则是发送不了的。

2、命令名称：wall

　　执行权限：所有用户

　　功能描述：向所有用户广播信息

　　语法：wall [message]  [文件名]

root向所有登陆用户发送信息

[root@localhost ~]# wall Happy New Year

Broadcast message from root@localhost.localdomain (pts/0) (Thu Nov 22 05:27:49 2012):

Happy New Year
[root@localhost ~]#

已登陆的用户就可以收到
[luxh@localhost ~]$ 
Broadcast message from root@localhost.localdomain (pts/0) (Thu Nov 22 05:27:49 2012):

Happy New Year

3、命令名称：ping

　　执行权限：root

　　功能描述：测试网络连通性

　　语法：ping [选项]  IP地址

在Linux下直接ping ID,按CTRL+C终止命令，否则会一直ping
[root@localhost ~]# ping 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.66 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=6.63 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=3.13 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=4.55 ms
64 bytes from 192.168.1.1: icmp_seq=5 ttl=128 time=6.69 ms
64 bytes from 192.168.1.1: icmp_seq=6 ttl=128 time=5.90 ms
64 bytes from 192.168.1.1: icmp_seq=7 ttl=128 time=2.77 ms
64 bytes from 192.168.1.1: icmp_seq=8 ttl=128 time=2.75 ms
64 bytes from 192.168.1.1: icmp_seq=9 ttl=128 time=5.41 ms
64 bytes from 192.168.1.1: icmp_seq=10 ttl=128 time=7.52 ms

　　

 使用 -c 指定ping的次数
[luxh@localhost ~]$ ping -c 4 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
64 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.49 ms
64 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=5.42 ms
64 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=2.46 ms
64 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=3.69 ms

--- 192.168.1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3010ms
rtt min/avg/max/mdev = 2.464/4.520/6.498/1.551 ms
[luxh@localhost ~]$ 

使用 -s 指定发送包的大小，最大不能超过65507字节
[root@localhost ~]# ping -c 4 -s 1024 192.168.1.1
PING 192.168.1.1 (192.168.1.1) 1024(1052) bytes of data.
1032 bytes from 192.168.1.1: icmp_seq=1 ttl=128 time=6.67 ms
1032 bytes from 192.168.1.1: icmp_seq=2 ttl=128 time=4.21 ms
1032 bytes from 192.168.1.1: icmp_seq=3 ttl=128 time=9.06 ms
1032 bytes from 192.168.1.1: icmp_seq=4 ttl=128 time=5.09 ms

--- 192.168.1.1 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3010ms
rtt min/avg/max/mdev = 4.212/6.262/9.064/1.845 ms
[root@localhost ~]# 

　　

4、命令名称：ifconfig

　　执行权限：root

　　功能描述：查看网络设置信息

　　语法：ifconfig [-a]  [网卡设备标识]

　　　　　　-a　　显示所有网卡的信息 （在Linux系统中可以省略，在Unix系统中不能省略）

[root@localhost ~]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:4C:63:3E  
          inet addr:192.168.0.102  Bcast:192.168.0.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe4c:633e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:4238 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3578 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:4560042 (4.3 MiB)  TX bytes:299603 (292.5 KiB)
          Interrupt:19 Base address:0x2024 

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:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:480 (480.0 b)  TX bytes:480 (480.0 b)

　　　eth0是实际的物理网卡，lo是虚拟的回环地址网卡

临时改变IP地址，重启后无效
[root@localhost ~]# ifconfig eth0 192.168.1.5