Learning examples of conventional network configuration commands and advanced IP address routing commands

Source: Internet
Author: User

Learning examples of conventional network configuration commands and advanced IP address routing commands
By kindgeorge 2005.5.9
Knowing how to configure network commands is a must-have technique for general technicians. After some time of research and study, I have summarized some common commands and examples for future reference.
The traditional IP advanced routing commands between and can be used in common and achieve the same purpose, but the IP is more powerful and can achieve more configuration purposes.

First, understand the traditional network configuration commands:
1. Use the ifconfig command to configure and view Network Interfaces

Example 1: configure the IP address of eth0 and activate the device at the same time:

# Ifconfig eth0 netmask up

Example 2: configure the IP address of the eth0 alias device eth0: 1 and add a route

# Ifconfig eth0: 1

# Route add-host Dev eth0: 1

Example 3: Activate (disable) a device

# Ifconfig eth0: 1 up (down)

Example 4: View All (specified) network interface configurations

# Ifconfig (eth0)

2. Use the route command to configure the route table

Example 1: add to host route

# Route add-host Dev eth0: 1

# Route add-host GW

Example 2: route added to the network

# Route add-net IP netmask mask eth0

# Route add-net IP netmask mask GW IP

# Route add-net IP/24 eth1

Example 3: Add a default gateway

# Route add default GW IP

Example 4: delete a route

# Route del-host Dev eth0: 1
Example 5: view route information
# Route or route-N (-N indicates that no name is parsed, And the list speed is faster than route)

3. ARP management commands
Example 1: View ARP cache


Example 2: add

# ARP-s IP Mac

Example 3: delete


4. IP is a powerful network configuration tool in iproute2, which can replace some traditional network management tools. For example, ifconfig and route,
The preceding example can be fully implemented using the following ip command, and the ip command can implement more functions. The following describes some examples:

4.0 ip command syntax

The ip command is used as follows:

IP [Options] object [Command [arguments]

4.1 IP link set -- change device properties. Abbreviation: Set, S

Example 1: up/down start/Close the device.
# IP link set Dev eth0 up
This is equal to the traditional # ifconfig eth0 up (down)
Example 2: change the length of the device transmission queue.
Parameter: txqueuelen number or txqlen number
# IP link set Dev eth0 txqueuelen 100
Example 3: Change the MTU value of the network device.
# IP link set Dev eth0 MTU 1500
Example 4: Modify the MAC address of a network device.
Parameter: Address lladdress
# IP link set Dev eth0 address 00: 01: 4f: 00: 15: F1

4.2 IP link show -- display device properties. Abbreviations: Show, list, lst, sh, ls, l
If the-s option appears twice or more times, the IP will output more detailed error information statistics.
# IP-s link ls eth0
Eth0: MTU 1500 qdisc CBQ qlen 100
Link/ether 00: A0: CC: 66: 18: 78 brd ff: FF
RX: bytes packets errors dropped overrun MCAST
2449949362 2786187 0 0 0 0
RX errors: length CRC frame FIFO missed
0 0 0 0 0
TX: bytes packets errors dropped carrier collsns
178558497 1783946 332 0 332 35172
TX errors: aborted FIFO window heartbeat
0 0 0 332
This command is equivalent to the traditional ifconfig eth0

5.1 IP address add -- Add a new Protocol address. Abbreviation: add,
Example 1: Set a string for each address as a tag. To be compatible with the Linux-2.0's network alias, this string must start with the device name, followed by a colon,
# Ip addr add local BRD + label eth0: 1 Dev eth0
Example 2: add an IP address to the Ethernet interface eth0. The mask length is 24 bits (, the standard broadcast address, and the label is eth0: alias:
# Ip addr add BRD + Dev eth1 label eth1: 1
This command is equivalent to the traditional: ifconfig eth1: 1

5.2 IP address Delete -- delete a Protocol address. Abbreviations: delete, Del, and D
# Ip addr del BRD + Dev eth0 label eth0: alias1

5.3 IP address show -- display Protocol address. Abbreviation: Show, list, lst, sh, ls, l
# Ip addr ls eth0

5.4.ip address flush -- clear Protocol address. Abbreviation: flush, F
Example 1: Delete all addresses in the private network
# IP-s a f-10/8
Example 2: cancel the IP addresses of all Ethernet cards
# IP-4 ADDR flush label "eth0"

6. IP neighbor -- neighbor/ARP table management command
Abbreviations: neighbor, neighbor, neigh, n
Command add, change, replace, delete, fulsh, show (or list)

6.1 IP neighbor add -- Add a new adjacent entry
IP neighbor change -- modify an existing entry
IP neighbor Replace -- replace an existing entry
Abbreviation: add, A; change, chg; replace, REPL
Example 1: Add a permanent ARP entry for address on the eth0:
# IP neigh add lladdr 0: 0: 0: 0: 0: 1 Dev eth0 NUD perm
Example 2: change the status to reachable.
# IP neigh chg Dev eth0 NUD reachable

6.2.ip neighbor Delete -- delete an adjacent entry
Example 1: delete an ARP entry on the eth0 device.
# IP neigh del Dev eth0
6.3.ip neighbor show -- display network neighbor information. Abbreviations: Show, list, sh, ls
Example 1: # IP-S n ls Dev eth0 lladdr 00: 00: 0C: 76: 3f: 85 ref 5 used 12/13/20 NUD reachable
6.4.ip neighbor flush -- clear the adjacent entries. Abbreviations: flush, F
Example 1: (-S can display details)
# IP-s n f

7. Route table management
. Abbreviated route, Ro, R
7. 5. Route table
Starting from the Linux-2.2, the kernel has summarized the route into many routing tables that are numbered in the range of numbers 1 to 255. In addition,
For convenience, you can also name the route table in/etc/iproute2/rt_tables.
By default, all routes are inserted into the main table (No. 254. During route query, the kernel only uses the route table main.

7.6.ip route add -- Add a new route entry
IP route change -- modify a route
IP Route Replace -- replace existing routes
Abbreviation: add, A; change, chg; replace, REPL
Example 1: The route destined for 10.0.0/24 goes through the gateway
# IP Route add 10.0.0/24 Via

Example 2: Modify the direct route to 10.0.0/24 so that it passes through the device dummy
# IP Route chg 10.0.0/24 Dev dummy

Example 3: Achieve link load balancing. Add the default multi-path routing to share the load between ppp0 and ppp1 (Note: The scope value is not required, but it only tells the kernel,
This route must go through the gateway instead of directly connected. In fact, if you know the address of the remote endpoint, it is better to use the via Parameter ).
# IP Route add default scope global nexthop Dev ppp0 nexthop Dev ppp1
# IP Route replace default scope global nexthop Dev ppp0 nexthop Dev ppp1
Example 4: configure a NAT route. Before forwarding a packet from, convert the network address to
# IP Route add Nat via

Example 5: Achieve Packet-level load balancing and allow random packet sending from multiple routes. You can set the weight for weight.
# IP Route replace default equalize nexthop via Dev eth0 weight 1 nexthop via Dev eth1 weight 1

7.7.ip route Delete -- delete a route
Abbreviation: delete, Del, d
Example 1: Delete the multi-path route added to the previous command
# IP Route del default scope global nexthop Dev ppp0 nexthop Dev ppp1

7.8.ip route show -- list routes
Abbreviations: Show, list, sh, ls, l

Example 1: calculate the number of routes using the gated/BGP protocol
# IP Route ls proto gated/BGP | WC
1413 9891 79010

Example 2: calculate the number of cached routes. The-O option is required because the cached route attributes may be greater than one row.
# IP-O route ls cloned | WC
159 2543 18707
Example 3: List the routes in the tableid of the route table. The default setting is table main. Tableid is either a real route table ID or a string defined in the/etc/iproute2/rt_tables file,
Or the following special values:
All -- lists the routes of all tables;
Cache-list the content of the route cache.
IP Ro ls tab Cache
Example 4: list the contents of a route table
# IP Route ls table fddi153

Example 5: list the content of the default route table
# IP Route ls
This command is equivalent to the traditional: Route

7.9.ip route flush -- Erase the route table
Example 1: Delete All gateway routes in the main route table (example: After the route monitoring program fails ):
# IP-4 Ro flush scope global type unicast
Example 2: Clear all cloned IPv6 routes:
# IP-6-s RO flush Cache
Example 3: Clear all BGP routes after the gated program fails:
# IP-s ro f proto gated/BGP
Example 4: Clear all IPv4 route caches
# IP Route flush Cache
* ** IPv4 routing cache is flushed.
7.10 IP Route get -- obtain a single route. Abbreviation: Get, G
Use this command to obtain a route entry to the destination address and its exact content.
The operations performed by the IP Route GET command and the IP route show command are different. The IP route show command only displays existing routes, while the IP Route GET command derives a new route when necessary.
Example 1: Search for Route
# IP Route get Dev eth0 SRC realms INR. AC cache MTU 1500 RTT 300
Example 2: The Search destination address is, from, the route from the eth0 device (this command will generate a very interesting route, This is a loop route to
# Ip r g from IIF eth0 from Dev eth0 SRC realms INR. AC/INR. AC
Cache <Src-direct, redirect>; MTU 1500 RTT 300 IIF eth0

8. IP route-database management commands for routing policies
Command add, delete, show (or list)
Note: Policy Routing is not equal to rouing policy ).
In some cases, we do not only need to determine the route through the destination address of the data packet, but also need to use other domains: the source address, IP protocol, transport layer port, and even the load of the data packet.
This is called policy routing ).

8.5. IP rule add -- Insert a new rule
IP rule Delete -- delete a rule
Abbreviation: add, A; delete, Del, d

Example 1: Route data packets whose source address is 192.203.80/24 by using the INR. ruhete route table
IP Ru add from 192.203.80/24 table INR. ruhoo PRIO 220

Example 2: Convert the source address of a datagram whose source address is to, and route it through table 1
IP Ru add from Nat Table 1 PRIO 320

Example 3: delete useless default rules
IP Ru del PRIO 32767

8.7. IP rule show -- list routing rules
Abbreviations: Show, list, sh, ls, l
Example 1: # IP Ru ls
0: from all lookup local
32762: From lookup fddi153
32764: From lookup fddi153
32766: from all lookup main
32767: from all lookup 253

9. IP maddress-multicast address management
Abbreviations: Show, list, sh, ls, l
9.3.ip maddress show -- list multicast addresses
Example 1: # IP maddr ls dummy

9.4. IP maddress add -- add multicast address
IP maddress Delete -- delete multicast address
Abbreviation: add, A; delete, Del, d
With these two commands, we can add/Delete the link layer multicast address listened on the network interface. This command can only manage link layer addresses.

Example 1: Add # IP maddr add 33: 33: 00: 00: 00: 01 Dev dummy
Example 2: view # IP-O maddr ls dummy
2: dummy
Link 33: 33: 00: 00: 00: 01 users 2 static
Link 01: 00: 5E: 00: 00: 01
Example 3: delete # IP maddr del 33: 33: 00: 00: 00: 01 Dev dummy

10. IP mroute-Multicast Route Cache Management

10.4. IP mroute show -- list Multicast Route cache entries
Abbreviations: Show, list, sh, ls, l

Example 1: view # IP mroute ls
(, IIF: unresolved
(, IIF: unresolved
(, IIF: eth0 oifs: pimreg
Example 2: view # IP-s Mr ls 224.66/16
(, IIF: eth0 oifs: pimreg
9383 packets, 300256 bytes

11. IP Tunnel-Channel Configuration
Tunnel and tunl

11.4.ip tunnel add -- Add a new channel
IP Tunnel change -- modify existing channel
IP Tunnel Delete -- delete a channel
Abbreviations: add, A; change, chg; delete, Del, d
Example 1: Create a point-to-point channel with a maximum TTL of 32
# IP Tunnel add Cisco mode sit remote local TTL 32

11.4.ip tunnel show -- Some channels appear in the column
Abbreviations: Show, list, sh, ls, l
Example 1: # IP-s tunl ls Cisco

12. IP monitor and rtmon -- Status Monitoring
IP commands can be used to continuously monitor the status of devices, addresses, and routes. The format of this command option is a bit different. The Command Option name is monitor, followed by the operation object:
IP monitor [file] [All | object-list]
Example 1: # rtmon file/var/log/rtmon. Log
Example 2: # IP monitor file/var/log/rtmon. log R

The ip command Manual (1-4) is available in:
Ip command Manual (I): http://blog.chinaunix.net/article.php? ArticleID = 16136 & blogid = 4543
Ip command Manual (2): http://blog.chinaunix.net/article.php? ArticleID = 16117 & blogid = 4543
Ip command Manual (3): http://blog.chinaunix.net/article.php? ArticleID = 24723 & blogid = 4543
Ip command Manual (4): http://blog.chinaunix.net/article.php? ArticleID = 24724 & blogid = 4543

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