diff --git a/sources/tech/20210125 Why you need to drop ifconfig for ip.md b/sources/tech/20210125 Why you need to drop ifconfig for ip.md new file mode 100644 index 0000000000..4bbe5b2cdc --- /dev/null +++ b/sources/tech/20210125 Why you need to drop ifconfig for ip.md @@ -0,0 +1,214 @@ +[#]: collector: (lujun9972) +[#]: translator: ( ) +[#]: reviewer: ( ) +[#]: publisher: ( ) +[#]: url: ( ) +[#]: subject: (Why you need to drop ifconfig for ip) +[#]: via: (https://opensource.com/article/21/1/ifconfig-ip-linux) +[#]: author: (Rajan Bhardwaj https://opensource.com/users/rajabhar) + +Why you need to drop ifconfig for ip +====== +Start using the modern method for configuring a Linux network interface. +![Tips and gears turning][1] + +For a long time, the `ifconfig` command was the default method for configuring a network interface. It served Linux users well, but networking is complex, and the commands to configure it must be robust. The `ip` command is the new default networking command for modern systems, and in this article, I'll show you how to use it. + +The `ip` command is functionally organized on two layers of the [OSI networking stack][2]: Layer 2 (data link layer) and Layer 3 (network or IP layer). It does all the work in the old `net-tools` package. + +### Installing ip + +The `ip` command is included in the `iproute2util` package. It's probably already included in your Linux distribution. If it's not, you can install it from your distro's software repository. + +### Comparing ipconfig and ip usage + +The `ip` and `ipconfic` commands can be used to configure a network interface, but they do things differently. I'll compare how to do common tasks with the old (`ipconfig`) and new (`ip`) commands. + +#### View network interface and IP address + +If you want to see the IP address of a host or view network interface information, the old `ifconfig` command, with no arguments, provides a good summary: + + +``` +$ ifconfig +                                                                                                 +eth0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500                                                                  +       ether bc:ee:7b:5e:7d:d8  txqueuelen 1000  (Ethernet)                                                        +       RX packets 0  bytes 0 (0.0 B) +       RX errors 0  dropped 0  overruns 0  frame 0 +       TX packets 0  bytes 0 (0.0 B) +       TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0 + +lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536 +       inet 127.0.0.1  netmask 255.0.0.0 +       inet6 ::1  prefixlen 128  scopeid 0x10<host> +       loop  txqueuelen 1000  (Local Loopback) +       RX packets 41  bytes 5551 (5.4 KiB) +       RX errors 0  dropped 0  overruns 0  frame 0 +       TX packets 41  bytes 5551 (5.4 KiB) +       TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0 + +wlan0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500 +       inet 10.1.1.6  netmask 255.255.255.224  broadcast 10.1.1.31 +       inet6 fdb4:f58e:49f:4900:d46d:146b:b16:7212  prefixlen 64  scopeid 0x0<global> +       inet6 fe80::8eb3:4bc0:7cbb:59e8  prefixlen 64  scopeid 0x20<link> +       ether 08:71:90:81:1e:b5  txqueuelen 1000  (Ethernet) +       RX packets 569459  bytes 779147444 (743.0 MiB) +       RX errors 0  dropped 0  overruns 0  frame 0 +       TX packets 302882  bytes 38131213 (36.3 MiB) +       TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0 +``` + +The new `ip` command provides similar results, but the command is `ip address show`, or just `ip a` for short: + + +``` +$ ip a + +1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000 +   link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 +   inet 127.0.0.1/8 scope host lo +      valid_lft forever preferred_lft forever +   inet6 ::1/128 scope host   +      valid_lft forever preferred_lft forever +2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN group default qlen 1000 +   link/ether bc:ee:7b:5e:7d:d8 brd ff:ff:ff:ff:ff:ff +3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000 +   link/ether 08:71:90:81:1e:b5 brd ff:ff:ff:ff:ff:ff +   inet 10.1.1.6/27 brd 10.1.1.31 scope global dynamic wlan0 +      valid_lft 83490sec preferred_lft 83490sec +   inet6 fdb4:f58e:49f:4900:d46d:146b:b16:7212/64 scope global noprefixroute dynamic   +      valid_lft 6909sec preferred_lft 3309sec +   inet6 fe80::8eb3:4bc0:7cbb:59e8/64 scope link   +      valid_lft forever preferred_lft forever +``` + +#### Add IP address + +To add an IP address to an interface with `ifconfig`, the command is: + + +``` +`$ ifconfig eth0 add 192.9.203.21` +``` + +The command is similar for `ip`: + + +``` +`$ ip address add 192.9.203.21 dev eth0` +``` + +Subcommands in `ip` can be shortened, so this command is equally valid: + + +``` +`$ ip addr add 192.9.203.21 dev eth0` +``` + +You can make it even shorter: + + +``` +`$ ip a add 192.9.203.21 dev eth0` +``` + +#### Remove an IP address + +The inverse of adding an IP address is to remove one. + +With `ifconfig`, the syntax is: + + +``` +`$ ifconfig eth0 del 192.9.203.21` +``` + +The `ip` command syntax is: + + +``` +`$ ip a del 192.9.203.21 dev eth0` +``` + +#### Enable or disable multicast + +Enabling (or disabling) [multicast][3] on an interface with `ifconfig` happens with the `multicast` argument: + + +``` +`# ifconfig eth0 multicast` +``` + +With `ip`, use the `set` subcommand with the device (`dev`) and a Boolean or toggle `multicast` option: + + +``` +`# ip link set dev eth0 multicast on` +``` + +#### Enable or disable a network + +Every sysadmin is familiar with the old "turn it off and then on again" trick to fix a problem. In terms of networking interfaces, that translates to bringing a network up or down. + +The `ifconfig` command does this with the `up` or `down` keywords: + + +``` +`# ifconfig eth0 up` +``` + +Or you could use a dedicated command: + + +``` +`# ifup eth0` +``` + +The `ip` command uses the `set` subcommand to set the interface to an `up` or `down` state: + + +``` +`# ip link set eth0 up` +``` + +#### Enable or disable the Address Resolution Protocol (ARP) + +With `ifconfig`, you enable ARP by declaring it: + + +``` +`# ifconfig eth0 arp` +``` + +With `ip`, you _set_ the `arp` property as `on` or `off`: + + +``` +`# ip link set dev eth0 arp on` +``` + +### Pros and cons of ip and ipconfig + +The `ip` command is more versatile and technically more efficient than `ifconfig` because it uses `Netlink` sockets rather than `ioctl` system calls. + +The `ip` command may appear more verbose and more complex than `ifconfig`, but that's one reason it's more versatile. Once you start using it, you'll get a feel for its internal logic (for instance, using `set` instead of a seemingly arbitrary mix of declarations or settings). + +Ultimately, `ifconfig` is outdated (for instance, it lacks full support for network namespaces), and `ip` is designed for the modern network. Try it out, learn it, use it. You'll be glad you did! + +-------------------------------------------------------------------------------- + +via: https://opensource.com/article/21/1/ifconfig-ip-linux + +作者：[Rajan Bhardwaj][a] +选题：[lujun9972][b] +译者：[译者ID](https://github.com/译者ID) +校对：[校对者ID](https://github.com/校对者ID) + +本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出 + +[a]: https://opensource.com/users/rajabhar +[b]: https://github.com/lujun9972 +[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/gears_devops_learn_troubleshooting_lightbulb_tips_520.png?itok=HcN38NOk (Tips and gears turning) +[2]: https://en.wikipedia.org/wiki/OSI_model +[3]: https://en.wikipedia.org/wiki/Multicast