Overview
By the end of this article you should be able to answer the following questions:
Announcement
You can find all my latest posts on medium.$ ip addr show
$ ip route show
$ ip -s link show
The ip command is mainly used for querying your network setup. The ip command is made up lots of sub commands (which you can display using the tab+tab technique). One commonly used subcommand is ip addr show
. This shows current interfaces along with their addressing info:
$ ip addr show 1: lo:mtu 65536 qdisc noqueue state UNKNOWN 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: enp0s3: mtu 1500 qdisc pfifo_fast state UP qlen 1000 link/ether 08:00:27:82:83:fc brd ff:ff:ff:ff:ff:ff inet 192.168.1.124/24 brd 192.168.1.255 scope global dynamic enp0s3 valid_lft 81874sec preferred_lft 81874sec inet6 fe80::a00:27ff:fe82:83fc/64 scope link valid_lft forever preferred_lft forever
This shows that our machine’s ip number is 192.168.1.124 (and it is part of a network that has a subnet mask of 24). However an easier way to output your machine’s ip number is:
Now let’s view the current routing table:
$ ip route show default via 192.168.1.1 dev enp0s3 proto static metric 100 192.168.1.0/24 dev enp0s3 proto kernel scope link src 192.168.1.124 metric 100
Here the router ip address is 192.168.1.1, which is the default gateway. Anything that falls in the 192.168.1.0/24 subnet will use the 192.168.1.1 (i.e. the router) as the default gateway.
Any outgoing data will automatically get directed to the default gateway, potentially through a series of switches. To improve performance you may want to add a new route which helps data to bypass switches and reaches it’s destination faster. This is done by adding a new route, like this:
To view data transfer statistics we do:
$ ip -s link show 1: lo:mtu 65536 qdisc noqueue state UNKNOWN mode DEFAULT link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 RX: bytes packets errors dropped overrun mcast 420 4 0 0 0 0 TX: bytes packets errors dropped carrier collsns 420 4 0 0 0 0 2: enp0s3: mtu 1500 qdisc pfifo_fast state UP mode DEFAULT qlen 1000 link/ether 08:00:27:82:83:fc brd ff:ff:ff:ff:ff:ff RX: bytes packets errors dropped overrun mcast 704513 7732 0 0 0 120 TX: bytes packets errors dropped carrier collsns 266335 1391 0 0 0 0