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How to communciate between two tap interfaces on two machines?

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2 answers
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I have two debian based machines with IP adresses XXX.XXX.8.76/26 and XXX.XXX.8.77/26. Now i need to create a tap0 interface on both machines for an application that communicates with UDP messages. But it is not possible for me to send a UDP messages between both tap0's. tap0 eno1 eno1 tap0 I simply created the tap0 with ip tuntap add dev tap0 mode tap After this I bridge the tap0 and the physical ethernet adapter with the following script:
#!/bin/bash

# Exit on error
set -e

# Define variables
BRIDGE=br0
ETH_IFACE=eno1
TAP_IFACE=tap0
IP_ADDR=XXX.XXX.8.76/26
GATEWAY=XXX:XXX.8.65  

# Check if run as root
if [ "$EUID" -ne 0 ]; then 
  echo "Please run as root"
  exit
fi

echo "Creating bridge $BRIDGE..."
ip link add $BRIDGE type bridge

echo "Bringing up the bridge..."
ip link set $BRIDGE up

echo "Adding $ETH_IFACE and $TAP_IFACE to $BRIDGE..."
ip link set $ETH_IFACE master $BRIDGE
ip link set $TAP_IFACE master $BRIDGE

echo "Bringing up $ETH_IFACE and $TAP_IFACE..."
ip link set $ETH_IFACE up
ip link set $TAP_IFACE up

echo "Assigning IP address to $BRIDGE..."
ip addr flush dev $ETH_IFACE
ip addr add $IP_ADDR dev $BRIDGE

echo "Setting up default gateway..."
ip route add default via $GATEWAY dev $BRIDGE

echo "Bridge setup complete. Current configuration:"
ip addr show $BRIDGE
bridge link show
If you have solutions that don't include a bridge I'm glad to hear them too :) The program I want to run is the lwIP Stack.
Asked by Simon (1 rep)
Feb 27, 2025, 09:48 PM
Last activity: Mar 11, 2025, 09:56 AM