feat: add ethernet & TCP/IP stack

2026-02-17 13:19:11 +01:00
parent f7e6ce70a0
commit 20fa8a9be2
23 changed files with 2409 additions and 0 deletions
@@ -0,0 +1,70 @@
+#!/bin/bash
+# Sets up a bridge + TAP device so QEMU guests appear on the local LAN.
+# Requires root. Idempotent — safe to run multiple times.
+
+set -e
+
+BRIDGE=br0
+TAP=tap0
+PHYS=enp0s31f6
+USER=$(logname 2>/dev/null || echo "${SUDO_USER:-daniel-hammer}")
+
+# Check if physical interface is already in the bridge (properly)
+PHYS_MASTER=$(ip -j link show dev "$PHYS" 2>/dev/null | grep -oP '"master"\s*:\s*"\K[^"]+' || true)
+
+if [ "$PHYS_MASTER" = "$BRIDGE" ] && ip link show "$TAP" &>/dev/null; then
+    echo "Bridge $BRIDGE with $PHYS and $TAP already set up."
+    exit 0
+fi
+
+echo "Creating bridge $BRIDGE..."
+ip link add name "$BRIDGE" type bridge 2>/dev/null || true
+ip link set "$BRIDGE" up
+
+# Tell NetworkManager to leave our interfaces alone (if NM is running)
+if command -v nmcli &>/dev/null; then
+    nmcli device set "$PHYS" managed no 2>/dev/null || true
+    nmcli device set "$BRIDGE" managed no 2>/dev/null || true
+fi
+
+# Move physical interface into bridge (if not already)
+if [ "$PHYS_MASTER" != "$BRIDGE" ]; then
+    echo "Moving $PHYS into bridge $BRIDGE..."
+
+    # Grab current IP config before moving
+    ADDR=$(ip -4 addr show dev "$PHYS" | grep -oP 'inet \K[\d.]+/\d+' | head -1)
+    GW=$(ip route show default dev "$PHYS" | grep -oP 'via \K[\d.]+' | head -1)
+
+    ip addr flush dev "$PHYS"
+    ip link set "$PHYS" master "$BRIDGE"
+
+    # Apply IP config to bridge
+    if [ -n "$ADDR" ]; then
+        ip addr add "$ADDR" dev "$BRIDGE" 2>/dev/null || true
+        echo "Assigned $ADDR to $BRIDGE"
+    fi
+    if [ -n "$GW" ]; then
+        ip route add default via "$GW" dev "$BRIDGE" 2>/dev/null || true
+        echo "Set default gateway $GW via $BRIDGE"
+    fi
+else
+    echo "$PHYS already in $BRIDGE"
+fi
+
+# Create TAP device (if not already)
+if ! ip link show "$TAP" &>/dev/null; then
+    echo "Creating TAP $TAP for user $USER..."
+    ip tuntap add dev "$TAP" mode tap user "$USER"
+    ip link set "$TAP" master "$BRIDGE"
+    ip link set "$TAP" up
+else
+    echo "TAP $TAP already exists"
+    ip link set "$TAP" up 2>/dev/null || true
+fi
+
+if command -v nmcli &>/dev/null; then
+    nmcli device set "$TAP" managed no 2>/dev/null || true
+fi
+
+echo "Network bridge setup complete: $PHYS -> $BRIDGE <- $TAP"
+ip -4 addr show dev "$BRIDGE" | head -3
@@ -0,0 +1,38 @@
+#!/bin/bash
+# Tears down the bridge + TAP setup and restores the physical interface.
+# Requires root.
+
+set -e
+
+BRIDGE=br0
+TAP=tap0
+PHYS=enp0s31f6
+
+if ! ip link show "$TAP" &>/dev/null; then
+    echo "TAP $TAP doesn't exist, nothing to tear down."
+    exit 0
+fi
+
+echo "Tearing down network bridge..."
+
+# Grab IP config from bridge before removing
+ADDR=$(ip -4 addr show dev "$BRIDGE" 2>/dev/null | grep -oP 'inet \K[\d.]+/\d+')
+GW=$(ip route show default dev "$BRIDGE" 2>/dev/null | grep -oP 'via \K[\d.]+' | head -1)
+
+# Remove TAP
+ip link set "$TAP" down 2>/dev/null || true
+ip link delete "$TAP" 2>/dev/null || true
+
+# Remove physical interface from bridge and restore its config
+ip link set "$PHYS" nomaster 2>/dev/null || true
+ip link delete "$BRIDGE" type bridge 2>/dev/null || true
+
+# Restore IP config to physical interface
+if [ -n "$ADDR" ]; then
+    ip addr add "$ADDR" dev "$PHYS" 2>/dev/null || true
+fi
+if [ -n "$GW" ]; then
+    ip route add default via "$GW" dev "$PHYS" 2>/dev/null || true
+fi
+
+echo "Network bridge torn down, $PHYS restored."