2025-01-27
The output of the ip addr show command
displays detailed information about the network interfaces on a Linux
system. Here’s a breakdown of the key components in the output:
Example Output
$ ip addr show
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
inet 192.168.1.10/24 brd 192.168.1.255 scope global eth0
valid_lft forever preferred_lft forever
inet6 fe80::250:56ff:fe88:ea0d/64 scope link
valid_lft forever preferred_lft foreverFields Interpretation
| Field | Description |
|---|---|
2: |
The interface index (in this case, the second network interface). |
eth0: |
The name of the network interface (could be eth0,
wlan0, lo, etc.). |
<BROADCAST,MULTICAST,UP,LOWER_UP> |
Flags describing the interface status. |
mtu 1500 |
The Maximum Transmission Unit (MTU), which is the largest packet size the interface can send. |
qdisc fq_codel |
The queuing discipline in use (i.e., how packets are scheduled for transmission). |
state UP |
The interface’s current state, which is UP (active) in
this case. |
group default |
The group this interface belongs to. |
qlen 1000 |
The length of the output packet queue. |
inet 192.168.1.10/24 |
The IPv4 address assigned to the interface
(192.168.1.10 with a subnet mask /24). |
brd 192.168.1.255 |
The broadcast address for the subnet. |
scope global |
The scope of the address (global means it’s publicly
routable). |
inet6 fe80::250:56ff:fe88:ea0d/64 |
The IPv6 address assigned to the interface
(fe80::250:56ff:fe88:ea0d with a subnet mask
/64). |
scope link |
The scope of the IPv6 address (link means it’s valid
only on the local network). |
valid_lft forever |
The lease time for the address (in this case, it’s “forever” for both IPv4 and IPv6). |
preferred_lft forever |
The preferred lifetime of the address (again, “forever” in this case). |