The ip command on Ubuntu (and modern Linux generally) replaces the older ifconfig and route commands. ip addr shows/manages IP addresses, ip route shows/manages routes, ip link shows/manages interfaces. ip -br gives compact output for scripts. The team that learns ip has a single tool for all networking.
Table of contents
- ip addr: show and set IPs
- ip route: show and set routes
- ip link: show and set interfaces
- ip neigh: ARP/ND table
- Useful one-liners
- FAQ
ip addr: show and set IPs
Show all addresses:
ip addr show
# or shorter
ip aCompact output:
ip -br addr show
# Output: lo UNKNOWN 127.0.0.1/8 ::1/128
# eth0 UP 192.0.2.10/24 fe80::1/64Add an IP:
sudo ip addr add 192.0.2.20/24 dev eth0Remove an IP:
sudo ip addr del 192.0.2.20/24 dev eth0The team that uses ip -br addr in scripts has clean output to parse.
ip route: show and set routes
Show routing table:
ip route show
# or
ip rAdd default route:
sudo ip route add default via 192.0.2.1Add specific route:
sudo ip route add 10.0.0.0/8 via 192.0.2.1 dev eth0Delete a route:
sudo ip route del 10.0.0.0/8The team that uses ip route get <dest> to debug routing finds the actual path packets take.
ip link: show and set interfaces
Show all interfaces:
ip link show
# or
ip lBring interface up/down:
sudo ip link set eth0 up
sudo ip link set eth0 downChange MTU:
sudo ip link set eth0 mtu 9000The team that uses ip link set eth0 up/down to reset an interface after config changes has the right pattern.
ip neigh: ARP/ND table
Show the neighbor table (ARP for IPv4, ND for IPv6):
ip neigh showUseful for debugging ‘is this host even on the network’ questions. The team that sees the expected MAC address has connectivity; the team that sees incomplete or no entry has a Layer 2 problem.
Useful one-liners
# Default gateway
ip route | grep default
# All IPs on this host
ip -j addr show | jq -r '.[].addr_info[].local'
# All listening ports
ss -tlnp
# Specific interface details
ip -d link show eth0
# All routes
ip route show table allThe team that uses these one-liners has fast answers to common questions.
FAQ
Where did ifconfig go?
Deprecated in favor of ip. Modern Ubuntu (18.04+) ships with iproute2 (which provides ip) and may not have ifconfig. The team that needs ifconfig installs net-tools, but ip is the right answer.
What’s the difference between ip and ip command?
Same thing - ip is the command, iproute2 is the package. The team that installs iproute2 gets ip.
How do I get my public IP?
From inside the host: curl -4 ifconfig.me or curl https://api.ipify.org. From outside: just look at your router or use a service like whatismyip.com.
Can I use ip to set up an entire network?
Yes - ip can set addresses, routes, vlan interfaces, bridges, bonds, tunnels, and more. The team that does serious network configuration uses ip + NetworkManager/Netplan/systemd-networkd for persistence.
How do I see TCP connections?
ss -tan (replace ifconfig’s old netstat). The team that uses ss has faster, more complete info than netstat.
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Useful related references: