Linux Networking: Routing, VLANs, Bridges, and Tunnels

ip route show

# Display the main routing table.

ip route get 8.8.8.8

# Show which route and source address will be used.

sudo ip route add default via 192.168.1.1 dev eth0

# Set a default gateway.

sudo ip route del default

# Remove the default gateway.

sudo ip route add 10.20.0.0/16 via 192.168.1.254 dev eth0

# Add a route for a remote network.

sudo ip route del 10.20.0.0/16

# Remove a static route.

ip rule show

# Display source-based and policy routing rules.

sudo ip rule add from 10.10.0.0/24 table 100

# Route traffic from a source CIDR using a specific table.

sudo ip route add default via 10.10.0.1 dev eth1 table 100

# Insert a route into an alternate routing table.

tracepath example.com

# Trace MTU and path to a host.

traceroute example.com

# Trace path hops to a host.

bridge link show

# Display interfaces participating in Linux bridges.

bridge fdb show

# Inspect learned MAC addresses on bridges.

sudo ip link add br0 type bridge

# Create a software bridge device.

sudo ip link set eth1 master br0

# Add an interface as a bridge port.

sudo ip link add link eth0 name eth0.100 type vlan id 100

# Create a VLAN-tagged interface.

sudo ip link add bond0 type bond mode active-backup

# Create a bonding interface.

sudo ip tunnel add gre1 mode gre local 10.0.0.1 remote 10.0.0.2 ttl 255

# Create a GRE tunnel interface.

sudo ip link add vxlan100 type vxlan id 100 dev eth0 remote 10.0.0.2 dstport 4789

# Create a VXLAN tunnel device.

ip neigh show

# Display IPv4 ARP and IPv6 neighbor entries.

sudo arping -I eth0 192.168.1.1

# Probe L2 reachability on the local subnet.