71 lines
2.2 KiB
Bash
Executable File
71 lines
2.2 KiB
Bash
Executable File
#!/bin/bash
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# Sets up a bridge + TAP device so QEMU guests appear on the local LAN.
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# Requires root. Idempotent — safe to run multiple times.
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set -e
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BRIDGE=br0
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TAP=tap0
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PHYS=enp0s31f6
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USER=$(logname 2>/dev/null || echo "${SUDO_USER:-daniel-hammer}")
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# Check if physical interface is already in the bridge (properly)
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PHYS_MASTER=$(ip -j link show dev "$PHYS" 2>/dev/null | grep -oP '"master"\s*:\s*"\K[^"]+' || true)
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if [ "$PHYS_MASTER" = "$BRIDGE" ] && ip link show "$TAP" &>/dev/null; then
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echo "Bridge $BRIDGE with $PHYS and $TAP already set up."
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exit 0
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fi
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echo "Creating bridge $BRIDGE..."
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ip link add name "$BRIDGE" type bridge 2>/dev/null || true
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ip link set "$BRIDGE" up
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# Tell NetworkManager to leave our interfaces alone (if NM is running)
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if command -v nmcli &>/dev/null; then
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nmcli device set "$PHYS" managed no 2>/dev/null || true
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nmcli device set "$BRIDGE" managed no 2>/dev/null || true
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fi
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# Move physical interface into bridge (if not already)
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if [ "$PHYS_MASTER" != "$BRIDGE" ]; then
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echo "Moving $PHYS into bridge $BRIDGE..."
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# Grab current IP config before moving
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ADDR=$(ip -4 addr show dev "$PHYS" | grep -oP 'inet \K[\d.]+/\d+' | head -1)
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GW=$(ip route show default dev "$PHYS" | grep -oP 'via \K[\d.]+' | head -1)
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ip addr flush dev "$PHYS"
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ip link set "$PHYS" master "$BRIDGE"
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# Apply IP config to bridge
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if [ -n "$ADDR" ]; then
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ip addr add "$ADDR" dev "$BRIDGE" 2>/dev/null || true
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echo "Assigned $ADDR to $BRIDGE"
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fi
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if [ -n "$GW" ]; then
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ip route add default via "$GW" dev "$BRIDGE" 2>/dev/null || true
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echo "Set default gateway $GW via $BRIDGE"
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fi
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else
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echo "$PHYS already in $BRIDGE"
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fi
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# Create TAP device (if not already)
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if ! ip link show "$TAP" &>/dev/null; then
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echo "Creating TAP $TAP for user $USER..."
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ip tuntap add dev "$TAP" mode tap user "$USER"
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ip link set "$TAP" master "$BRIDGE"
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ip link set "$TAP" up
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else
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echo "TAP $TAP already exists"
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ip link set "$TAP" up 2>/dev/null || true
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fi
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if command -v nmcli &>/dev/null; then
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nmcli device set "$TAP" managed no 2>/dev/null || true
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fi
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echo "Network bridge setup complete: $PHYS -> $BRIDGE <- $TAP"
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ip -4 addr show dev "$BRIDGE" | head -3
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