Add secondary IP

Assign a secondary IP/prefix live; note: not persisted across reboot

ip addr add 10.0.0.5/24 dev <name> && ip addr show dev <name>
tool
iproute212 commands
tags
iproute2networktroubleshooting

More iproute2 commands

  • Set interface MTU
    ip link set dev <name> mtu 9000 && ip link set dev <name> up

    Set jumbo MTU and bring link up; note: path MTU must match end-to-end

  • JSON addr to jq
    ip -j a | jq -r '.[] | select(.operstate=="UP") | .ifname + " " + (.addr_info[]?.local // "-")'

    Machine-readable interface dump; list UP links with their local IPs

  • Which route is chosen
    ip route get <ip>

    Show the exact route, src IP and oif the kernel picks for a destination

  • Source-based policy routing
    ip rule add from <ip> table 100 && ip route add default via 192.168.1.1 dev <name> table 100

    Route by source IP via a separate table; check with ip rule show

  • Run command in netns
    ip netns add test && ip netns exec test ip -br a

    Create an isolated network namespace and run commands inside it

all 12 iproute2 commands