Simple script for setting up bridges in linux

Examples

Create a new bridge named 'qemu_bridge' with tap3 and tap4 interface using ip address '192.168.42.50/24" and bring the bridge up

./setup_bridge.sh -b=qemu_bridge --addbridge -a -i=tap3 -i=tap4 -p="192.168.42.50/24" -u

Create a new bridge

./setup_bridge.sh -b=qemu_bridge --addbridge

Delete a bridge

./setup_bridge.sh -b=qemu_bridge --delbridge

Adding new interfaces to an existing bridge

./setup_bridge.sh -b=qemu_bridge -a -i=tap5 -i=tap6

Removing interfaces from an existing bridge

./setup_bridge.sh -b=qemu_bridge -r -i=tap5

Remove all interfaces from an existing bridge

./setup_bridge.sh -b=qemu_bridge --delall

Set IP Address of bridge

./setup_bridge.sh -b=qemu_bridge -p="192.168.42.50/24"

Show current attached interfaces of bridge

./setup_bridge.sh -b=qemu_bridge -s

Bring the bridge and all its interfaces up

./setup_bridge.sh -b=qemu_bridge -u

Bring the bridge and all its interfaces down

./setup_bridge.sh -b=qemu_bridge -d

Notes

Warning: if you have docker installed on your host, it may have created an iptable rule that forbids IP forwarding: the symptom will be that ARP will work, allowing your containers to see each other, but all IP traffic between your containers will be blocked. In that case, you need to disable iptables for network bridges (as root):

$ echo 0  | sudo tee /proc/sys/net/bridge/bridge-nf-call-iptables

You can monitor the IP traffic between the two containers using tshark (or tcpdump):

$ sudo tshark -i br0

Some interesting links

http://www.kaizou.org/2018/06/qemu-bridge.html

franzflasch / linux_bridge_scripts