2.route路由配置
转自 http://www.cnblogs.com/peida/archive/2013/03/05/2943698.html
Linux系统的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。
1.命令格式:
route [-f] [-p] [Command [Destination] [mask Netmask] [Gateway] [metric Metric]] [if Interface]]
2.命令功能:
Route命令是用于操作基于内核ip路由表,它的主要作用是创建一个静态路由让指定一个主机或者一个网络通过一个网络接口,如eth0。当使用"add"或者"del"参数时,路由表被修改,如果没有参数,则显示路由表当前的内容。
3.命令参数:
-c 显示更多信息
-n 不解析名字
-v 显示详细的处理信息
-F 显示发送信息
-C 显示路由缓存
-f 清除所有网关入口的路由表。
-p 与 add 命令一起使用时使路由具有永久性。
add:添加一条新路由。
del:删除一条路由。
-net:目标地址是一个网络。
-host:目标地址是一个主机。
netmask:当添加一个网络路由时,需要使用网络掩码。
gw:路由数据包通过网关。注意,你指定的网关必须能够达到。
metric:设置路由跳数。
Command 指定您想运行的命令 (Add/Change/Delete/Print)。
Destination 指定该路由的网络目标。
mask Netmask 指定与网络目标相关的网络掩码(也被称作子网掩码)。
Gateway 指定网络目标定义的地址集和子网掩码可以到达的前进或下一跃点 IP 地址。
metric Metric 为路由指定一个整数成本值标(从 1 至 9999),当在路由表(与转发的数据包目标地址最匹配)的多个路由中进行选择时可以使用。
if Interface 为可以访问目标的接口指定接口索引。若要获得一个接口列表和它们相应的接口索引,使用 route print 命令的显示功能。可以使用十进制或十六进制值进行接口索引。
4.使用实例:
实例1:显示当前路由
命令:
route
route -n
输出:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
e192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
0.0.0.0 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
说明:
第一行表示主机所在网络的地址为192.168.120.0,若数据传送目标是在本局域网内通信,则可直接通过eth0转发数据包;
第四行表示数据传送目的是访问Internet,则由接口eth0,将数据包发送到网关192.168.120.240
其中Flags为路由标志,标记当前网络节点的状态。
Flags标志说明:
U Up表示此路由当前为启动状态
H Host,表示此网关为一主机
G Gateway,表示此网关为一路由器
R Reinstate Route,使用动态路由重新初始化的路由
D Dynamically,此路由是动态性地写入
M Modified,此路由是由路由守护程序或导向器动态修改
! 表示此路由当前为关闭状态
备注:
route -n (-n 表示不解析名字,列出速度会比route 快)
实例2:添加网关/设置网关
命令:
route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
输出:
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
224.0.0.0 * 240.0.0.0 U 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]#
说明:
增加一条 到达244.0.0.0的路由
实例3:屏蔽一条路由
命令:
route add -net 224.0.0.0 netmask 240.0.0.0 reject
输出:
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
224.0.0.0 - 240.0.0.0 ! 0 - 0 -
224.0.0.0 * 240.0.0.0 U 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
说明:
增加一条屏蔽的路由,目的地址为 224.x.x.x 将被拒绝
实例4:删除路由记录
命令:
route del -net 224.0.0.0 netmask 240.0.0.0
route del -net 224.0.0.0 netmask 240.0.0.0 reject
输出:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
224.0.0.0 - 240.0.0.0 ! 0 - 0 -
224.0.0.0 * 240.0.0.0 U 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]# route del -net 224.0.0.0 netmask 240.0.0.0
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
224.0.0.0 - 240.0.0.0 ! 0 - 0 -
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]# route del -net 224.0.0.0 netmask 240.0.0.0 reject
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]#
说明:
实例5:删除和添加设置默认网关
命令:
route del default gw 192.168.120.240
route add default gw 192.168.120.240
输出:
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
[root@localhost ~]# route add default gw 192.168.120.240
[root@localhost ~]# route
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.120.0 * 255.255.255.0 U 0 0 0 eth0
192.168.0.0 192.168.120.1 255.255.0.0 UG 0 0 0 eth0
10.0.0.0 192.168.120.1 255.0.0.0 UG 0 0 0 eth0
default 192.168.120.240 0.0.0.0 UG 0 0 0 eth0
[root@localhost ~]#
说明:
http://www.tldp.org/HOWTO/Multicast-HOWTO-3.html
组播地址及路由
⑴ D类地址不分网络地址和主机地址,它的第1个字节的前四位固定为1110,即224
⑵ D类地址范围:224.0.0.1—239.255.255.254, 即1110000.00000000.00000000.00000001 - 11101111.11111111.11111111.1111110
Once you have compiled and installed your new kernel, you should provide a default route for multicast traffic. The goal is to add a route to the network 224.0.0.0.
The problem most people seem to face in this stage of the configuration is with the value of the mask to supply. If you have read Terry Dawson's excellent NET-3-HOWTO, it should not be difficult to guess the correct value, though. As explained there, the netmask is a 32 bit number filled with all-1s in the network part of your IP address, and with all-0s in the host part. Recall from section 2.1 that a class D multicast address has no netwok/host sections. Instead it has a 28-bit group identifier and a 4-bit class D identifier. Well, this 4 bits are the network part and the remaining 28 the host part. So the netmask needed is 11110000000000000000000000000000 or, easier to read: 240.0.0.0. Then, the full command should be:
route add -net 224.0.0.0 netmask 240.0.0.0 dev eth0
or
route add -net 224.0.0.0/4 dev eth0
Depending on how old your route
program is, you might need to add the -net
flag after the add
.
Here we supposed that eth0
was multicast-capable and that, when not otherwise specified, we wanted multicast traffic to be output there. If this is not your case, change the dev
parameter as appropriate.
The /proc
filesystem proves here to be useful once again: you can check /proc/net/igmp
to see the groups your host is currently subscribed to.