ip

1. Quick commands

ip -br -c [subcommand] # brief and colorized output

<BROADCAST,MULTICAST,UP,LOWER_UP> : Interface state.
- Broadcast & Multicast capable
- Interface is enabled (UP)
- Physical layer is connected (LOWER_UP)
mtu: Maximum transmission unit (MTU) for the interface. (Default is 1500 bytes)
qdisc : The queueing approach being used by the interface.
- noqueue : Send immediately
- noop : Drop all
state : Another indication of the operational state of an interface.
- UP and DOWN
- UNKNOWN : Interface is up and operational, but nothing is connected.
group : Interfaces can be grouped together on Linux to allow common attributes or commands. Usually default. Other usecase, eg. VM host system with 2 interfaces for management and 8 for data traffic. Group them into mgmt and data groups.
qlen : Eg. 1000 – The interface has a 1000 packet queue. The 1001st packet would be dropped.
inet:scope : global means globally reachable. Others can be link and host
inet:dynamic : DHCP was used. Leased info in valid_lft

ip link : shows interfaces, can make changes to interfaces
ip neigh : ARP table.
ip route : Routing table. src attribute is to specify source ip in multihomed setups.
- ip route get : Tells you which path will take (TODO)