Linux命令之route

浏览数：23 / 时间：2015年06月20日

转自：

http://codingstandards.iteye.com/blog/1125312

用途说明

route命令用于显示和操作IP路由表（show / manipulate the IP routing table）。要实现两个不同的子网之间的通信，需要一台连接两个网络的路由器，或者同时位于两个网络的网关来实现。在Linux系统中，设置路由通常是为了解决以下问题：该Linux系统在一个局域网中，局域网中有一个网关，能够让机器访问Internet，那么就需要将这台机器的IP地址设置为Linux机器的默认路由。要注意的是，直接在命令行下执行route命令来添加路由，不会永久保存，当网卡重启或者机器重启之后，该路由就失效了；可以在/etc/rc.local中添加route命令来保证该路由设置永久有效。本文中的例子中会验证这一点。

常用参数

格式：route

格式：/sbin/route

用于打印路由表（display the current routing table）。

在非root用户使用时需要使用完整路径执行route命令。

格式：route -n

格式：/sbin/route -n

用于打印路由表，加上-n参数就是在输出的信息中不打印主机名而直接打印ip地址。像netstat命令也有此参数。

格式：route add default gw {IP-ADDRESS} {INTERFACE-NAME}

用于设置默认路由（adds a default route, which will be used if no other route matches），其中，

参数{IP-ADDRESS): 用于指定路由器（网关）的IP地址（Specify router IP address）；
参数{INTERFACE-NAME}: 用于指定接口名称，如eth0（Specify interface name such as eth0）。使用/sbin/ifconfig -a可以显示所有接口信息。

man route 写道

route add default gw mango-gw
adds a default route (which will be used if no other route matches). All packets using this route will
be gatewayed through "mango-gw". The device which will actually be used for that route depends on how we
can reach "mango-gw" - the static route to "mango-gw" will have to be set up before.

格式：route add -net {NETWORK-ADDRESS} netmask {NETMASK} dev {INTERFACE-NAME}

添加到指定网络的路由规则，其中

参数{NETWORK-ADDRESS}: 用于指定网络地址

参数{NETMASK}: 用于指定子网掩码

参数{INTERFACE-NAME}: 用于指定接口名称，如eth0。

man route 写道

route add -net 192.56.76.0 netmask 255.255.255.0 dev eth0
adds a route to the network 192.56.76.x via "eth0". The Class C netmask modifier is not really necessary
here because 192.* is a Class C IP address. The word "dev" can be omitted here.

route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
This is an obscure one documented so people know how to do it. This sets all of the class D (multicast)
IP routes to go via "eth0". This is the correct normal configuration line with a multicasting kernel.

格式：route add -net {NETWORK-ADDRESS} netmask {NETMASK} reject

设置到指定网络为不可达，避免在连接到这个网络的地址时程序过长时间的等待，直接就知道该网络不可达。

man route 写道

route add -net 10.0.0.0 netmask 255.0.0.0 reject
This installs a rejecting route for the private network "10.x.x.x."

格式：route del -net {NETWORK-ADDRESS} netmask {NETMASK} dev {INTERFACE-NAME}

格式：route del -net {NETWORK-ADDRESS} netmask {NETMASK} reject

用于删除路由设置。参数指定的方式与route add相似。

route命令输出的路由表字段含义如下：

       Destination 目标
              The destination network or destination host. 目标网络或目标主机。

       Gateway 网关
              The gateway address or ‘*‘ if none set. 网关地址，如果没有就显示星号。

       Genmask 网络掩码
              The netmask for the destination net; ‘255.255.255.255‘ for a
              host destination and ‘0.0.0.0‘ for the default route.

       Flags Possible flags include 标志，常用的是U和G。
              U (route is up) 路由启用
              H (target is a host) 目标是主机
              G (use gateway) 使用网关
              R (reinstate route for dynamic routing)
              D (dynamically installed by daemon or redirect)
              M (modified from routing daemon or redirect)
              A (installed by addrconf)
              C (cache entry)
              ! (reject route)

       Metric 距离、跳数。暂无用。

              The ‘distance‘ to the target (usually counted in hops). It is
              not used by recent kernels, but may be needed by routing dae-
              mons.

       Ref   不用管，恒为0。

              Number of references to this route. (Not used in the Linux ker-
              nel.)

       Use    该路由被使用的次数，可以粗略估计通向指定网络地址的网络流量。

              Count of lookups for the route. Depending on the use of -F and
              -C this will be either route cache misses (-F) or hits (-C).

       Iface 接口，即eth0,eth0等网络接口名

Interface to which packets for this route will be sent.

使用示例

示例一打印当前路由表（root用户）

[root@jfht ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    *               255.255.255.224 U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 eth1
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
default         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]# /sbin/route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    *               255.255.255.224 U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 eth1
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
default         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]# route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    0.0.0.0         255.255.255.224 U     0      0        0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
0.0.0.0         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]# /sbin/route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    0.0.0.0         255.255.255.224 U     0      0        0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
0.0.0.0         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]#

示例二打印当前路由表（非root用户）

[web@hnweb1 ~]$ route
-bash: route: command not found
[web@hnweb1 ~]$ /sbin/route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.66.10.0      *               255.255.255.128 U     0      0        0 eth0
192.130.12.0    10.66.10.1      255.255.255.0   UG    0      0        0 eth0
10.0.0.0        *               255.255.255.0   U     0      0        0 eth1
10.66.0.0       10.66.10.1      255.255.0.0     UG    0      0        0 eth0
134.161.0.0     10.66.10.1      255.255.0.0     UG    0      0        0 eth0
10.20.0.0       10.66.10.1      255.255.0.0     UG    0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
172.224.0.0     10.66.10.1      255.255.0.0     UG    0      0        0 eth0
default         10.66.10.22     0.0.0.0         UG    0      0        0 eth0
[web@hnweb1 ~]$ route -n
-bash: route: command not found
[web@hnweb1 ~]$ /sbin/route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.66.10.0      0.0.0.0         255.255.255.128 U     0      0        0 eth0
192.130.12.0    10.66.10.1      255.255.255.0   UG    0      0        0 eth0
10.0.0.0        0.0.0.0         255.255.255.0   U     0      0        0 eth1
10.66.0.0       10.66.10.1      255.255.0.0     UG    0      0        0 eth0
134.161.0.0     10.66.10.1      255.255.0.0     UG    0      0        0 eth0
10.20.0.0       10.66.10.1      255.255.0.0     UG    0      0        0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U     0      0        0 eth1
172.224.0.0     10.66.10.1      255.255.0.0     UG    0      0        0 eth0
0.0.0.0         10.66.10.22     0.0.0.0         UG    0      0        0 eth0
[web@hnweb1 ~]$

示例三设置到某网络的路由的例子

下面的例子来自一个实际的服务器配置。 route命令写在了/etc/rc.local中，这样就设置了一条永久路由。

[root@jf07 root]# grep route /etc/rc.local
route add -net 10.0.0.0/8 gw 10.33.149.1 dev eth1
[root@jf07 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.32.181.182   10.33.149.1     255.255.255.255 UGH   0      0        0 eth1
10.33.136.135   10.33.149.1     255.255.255.255 UGH   0      0        0 eth1
10.32.208.13    10.33.149.1     255.255.255.255 UGH   0      0        0 eth1
10.33.149.0     *               255.255.255.128 U     0      0        0 eth1
192.168.1.0     *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
10.0.0.0        10.33.149.1     255.0.0.0       UG    0      0        0 eth1
default         192.168.1.254   0.0.0.0         UG    0      0        0 eth0
[root@jf07 root]#

示例四添加拒绝路由的测试

[root@jfht ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    *               255.255.255.224 U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 eth1
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
default         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]# ping 10.33.11.12
PING 10.33.11.12 (10.33.11.12) 56(84) bytes of data.
Ctrl+C
--- 10.33.11.12 ping statistics ---
21 packets transmitted, 0 received, 100% packet loss, time 19999ms

[root@jfht ~]# route add -net 10.0.0.0 netmask 255.0.0.0 reject
[root@jfht ~]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
211.103.28.0    *               255.255.255.224 U     0      0        0 eth0
192.168.1.0     *               255.255.255.0   U     0      0        0 eth1
169.254.0.0     *               255.255.0.0     U     0      0        0 eth1
10.0.0.0        -               255.0.0.0       !     0      -        0 -
default         211.103.28.1    0.0.0.0         UG    0      0        0 eth0
[root@jfht ~]# ping 10.33.11.12
connect: Network is unreachable
[root@jfht ~]#

示例五设置路由之后重启机器的测试

[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]# route add -net 10.0.0.0 netmask 255.0.0.0 reject
[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
10.0.0.0        -               255.0.0.0       !     0      -        0 -
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]# reboot

Broadcast message from root (pts/0) (Thu Jul 7 05:31:26 2011):

The system is going down for reboot NOW!
[root@node34 root]#

Last login: Thu Jul 7 05:30:50 2011 from 192.168.227.1
[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]#

上面的测试表明route设置的路由在机器重启之后就消失了。

示例六将route命令添加到/etc/rc.local来设置永久路由的测试

先用vi在/etc/rc.local后面添加route命令。

[root@node34 root]# tail /etc/rc.local
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don‘t
# want to do the full Sys V style init stuff.

touch /var/lock/subsys/local

# 2011.07.15 add permanent route test
route add -net 10.0.0.0 netmask 255.0.0.0 reject

[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]# reboot

Broadcast message from root (pts/0) (Fri Jul 15 14:43:44 2011):

The system is going down for reboot NOW!
[root@node34 root]#

Last login: Fri Jul 15 14:40:22 2011 from 192.168.227.1
[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
10.0.0.0        -               255.0.0.0       !     0      -        0 -
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]#

示例七删除路由的测试

删除路由的时候只需将route add改成route del，其他参数类似。如果报“无效的参数”或“没有那个进程”，可能是因为提供的参数不够。

[root@node34 root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.227.0   *               255.255.255.0   U     0      0        0 eth0
169.254.0.0     *               255.255.0.0     U     0      0        0 eth0
10.0.0.0        -               255.0.0.0       !     0      -        0 -
default         192.168.227.2   0.0.0.0         UG    0      0        0 eth0
[root@node34 root]#
[root@node34 root]# route del -net 10.0.0.0
SIOCDELRT: 无效的参数
[root@node34 root]# route del -net 10.0.0.0 netmask 255.0.0.0
SIOCDELRT: 没有那个进程
[root@node34 root]#
[root@node34 root]# route del -net 10.0.0.0 netmask 255.0.0.0 reject
[root@node34 root]#