Shall we say I’ve a server with two nics in it.
eno1: 192.168.1.100/24
eno2: 169.254.2.1/16
Site visitors in/out of Nic 1 has no downside. I can get ssh in, ping out, and many others. No downside. Nevertheless after operating a netplan generate && netplan apply on ubuntu24, and even operating ifconfig eno2 169.254.2.1 netmask 255.255.0.0 up, after I run tcpdump -i eno2 i see the ip tackle from eno1 egressing out eno2, as an alternative of the .2.1 tackle
prior:
**2:39:41.937488 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 169.254.2.1 > 169.254.2.2: ICMP echo request, id 27057, seq 1, size 64
22:39:41.938469 00:11:22:33:44:55 > aa:bb:cc:dd:ee:ff, ethertype IPv4 (0x0800), size 98: 169.254.2.2 > 169.254.2.1: ICMP echo reply, id 27057, seq 1, size 64
22:39:42.937626 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 169.254.2.1 > 169.254.2.2: ICMP echo request, id 27057, seq 2, size 64
22:39:42.938563 00:11:22:33:44:55 > aa:bb:cc:dd:ee:ff, ethertype IPv4 (0x0800), size 98: 169.254.2.2 > 169.254.2.1: ICMP echo reply, id 27057, seq 2, size 64
22:39:43.964645 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 169.254.2.1 > 169.254.2.2: ICMP echo request, id 27057, seq 3, size 64
22:39:43.965546 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 169.254.2.2 > 169.254.2.1: ICMP echo reply, id 27057, seq 3, size 64
After:
22:43:37.872518 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 192.168.1.100 > 169.254.2.2: ICMP echo request, id 29192, seq 1, size 64
22:43:38.908604 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 192.168.1.100 > 169.254.2.2: ICMP echo request, id 29192, seq 2, size 64
22:43:39.932634 aa:bb:cc:dd:ee:ff > 00:11:22:33:44:55, ethertype IPv4 (0x0800), size 98: 192.168.1.100 > 169.254.2.2: ICMP echo request, id 29192, seq 3, size 64
there’s a slight likelihood, that by doing an ifconfig down and up that it would instantly work once more, however for the lifetime of me i can not discover the trigger. there isn’t a router concerned, that is purely eno2 speaking to a different system straight related to it, and it is not one thing with the default route since I see the visitors egressing over eno2 and never eno1.
Thanks!