fix: properly setup outbound network connectivity in getting started

the getting started guide was hardcoding eth0 as the network interface on the host to route outbound microvm network traffic to. However, on EC2 instances (and my laptop), that's wrong, because its not called eth0. So instead dynamically determine the hopefully correct network interface on the host. Suggested-by: Pablo Barbáchano <[email protected]> Signed-off-by: Patrick Roy <[email protected]>
firecracker-microvm · Nov 28, 2024 · 8d01d76 · 8d01d76
1 parent 4c33853
commit 8d01d76
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/docs/getting-started.md b/docs/getting-started.md
@@ -197,8 +197,9 @@ sudo ip link set dev "$TAP_DEV" up
 
 # Enable ip forwarding
 sudo sh -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
+sudo iptables -P FORWARD ACCEPT
 
-HOST_IFACE="eth0"
+HOST_IFACE=$(ip -j route list default |jq -r '.[0].dev')
 
 # Set up microVM internet access
 sudo iptables -t nat -D POSTROUTING -o "$HOST_IFACE" -j MASQUERADE || true