ip — Check addresses, routing, and links

💬 "ip command"

ip is the standard tool that replaces ifconfig/route. It shows addresses (addr), links (link), and routes (route).

This is the first command to check interface status and the default gateway when network problems occur.

• Concept: Queries and configures network interface, address, and routing information.
• addr: IP address assigned to each interface.
• link: Interface status (UP/DOWN) and MAC address.
• route: Routing table and default gateway.

Frequently used options

3 essential command combinations

• ip -br a — View addresses at a glance in summary
• ip route get 8.8.8.8 — Check the outgoing route to a specific destination
• ip -s link show ens3 | tail -5 — Check interface error/drop counters

💬 "Show me an example of finding a problem that leaves no logs"

This is a step-by-step walkthrough of a situation commonly encountered on production servers.

Step 1 · Interface status

Check whether the link is UP.

ip -br link

Step 2 · Check address

Check whether an IP address has been assigned correctly.

ip -br a

Step 3 · Check routes

Check the default gateway and external routes.

ip route && ip route get 8.8.8.8

How it's used in practice

1. No outbound connectivity

Situation — The server cannot reach the outside.

ip -br a && ip route

Result — If an address exists but there is no default route, it is a gateway problem.

Point — Checking address, link, and route in order narrows down the cause layer by layer.

2. Interface error counters

Situation — Packet loss is suspected.

ip -s link show ens3

Result — If the errors/dropped counters increase, check cables, drivers, or load.

Point — Read the counters twice to check whether they are increasing.

Caution

• ip addr add/del changes the network immediately. It can disconnect your session when working remotely.
• ifconfig/route are no longer included by default on some distributions.
• To persist changes after reboot, use management tools such as netplan/NetworkManager.

Actual execution screen

This is the result of checking interface addresses and the routing table.

!ip command execution result: addresses and routing

A real production server

Source (HTML): https://games.aidebatehub.com/programs/linux/network/ip.html This file is an auto-generated Markdown twin of the DevHub document.