Describe the bug

After running through the steps in the getting started guide, the guest does not have outbound network connectivity. Things like ping 8.8.8.8, which work on the host, just hang indefinitely:

root@ubuntu-fc-uvm:~# ping 8.8.8.8         
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
^C
--- 8.8.8.8 ping statistics ---
12 packets transmitted, 0 received, 100% packet loss, time 11267ms

Note that this is broken both on main, as well as on the 1.10 branch (e.g. before the upgrade to Ubuntu 24)

To Reproduce

1. Follow the getting started guide
2. Run ping 8.8.8.8 inside the microVM and observe it failing

Expected behavior

I should have internet connectivity inside the microvm, e.g. the ping command should instead output

roypat@ua2d7e1a6107c5b:~/test$ ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_seq=1 ttl=117 time=44.0 ms
64 bytes from 8.8.8.8: icmp_seq=2 ttl=117 time=50.5 ms
^C
--- 8.8.8.8 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1001ms
rtt min/avg/max/mdev = 44.024/47.242/50.460/3.218 ms

Environment

[Author TODO: Please supply the following information):]

• Firecracker version: 1.10.1 and mainline
• Host and guest kernel versions: Host 6.1, guest 5.10 (from CI artifacts)
• Rootfs used: Ubuntu 22.04 and 24.04
• Architecture: x86_64 and aarch64

Checks

• Have you searched the Firecracker Issues database for similar problems?
• Have you read the existing relevant Firecracker documentation?
• Are you certain the bug being reported is a Firecracker issue?