Timeline for Why Linux answers ARP requests for IPs that belong to different network interfaces? [closed]
Current License: CC BY-SA 4.0
11 events
| when toggle format | what | by | license | comment | |
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| May 3, 2023 at 14:04 | comment | added | FrameHowitzer | Yes, I have been bitten by it before as well, years ago, and suspected this might be the same kind of thing but didn't want to, well, assume too much without asking for more details on the actual behavior. It's a frustrating design and never really made much sense to me why they did it. It's a deceptive failure that makes it seem things are working even though it would be better to fail more visibly. | |
| May 2, 2023 at 18:38 | comment | added | Ricky | @FrameHowitzer I wouldn't say "correct", but appropriate. As I answered, it's proxy_arp behavior, and likely not what anyone actually wants. But it's also something that should never happen. (I was around when they started this crap, but don't remember to exact logic behind it.) | |
| May 2, 2023 at 14:22 | comment | added | FrameHowitzer | Ah yes, ok so it is responding with correct addresses. As noted below that is default for Linux. It is a bit dumb in that way. It assumes that doing something, even if a bit wrong, is better than doing nothing. It should really do nothing in those cases but the traffic reaching it on the wrong network is also an indication that something else is wrong with the setup, probably. | |
| May 2, 2023 at 10:55 | history | closed | Ron Maupin♦ | Not suitable for this site | |
| May 2, 2023 at 4:04 | vote | accept | felipeek | ||
| May 2, 2023 at 3:54 | answer | added | Ricky | timeline score: 3 | |
| May 2, 2023 at 3:40 | comment | added | felipeek | Hi @FrameHowitzer, thanks for the answer, I updated the question with the real example. It always responds with the MAC address of eno1, which is the interface that received the ARP request, but not the interface that has that IP address. I find this behavior a bit weird, but I would imagine this is proposital | |
| May 2, 2023 at 3:39 | history | edited | felipeek | CC BY-SA 4.0 |
added 780 characters in body
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| May 2, 2023 at 3:30 | comment | added | FrameHowitzer | You should add some concrete examples of the IP addresses involved. Also, is the response correct? If the MAC address is correct for the interface then I would assume it is doing what it is supposed to do. What source IP is asking and what IP is it asking for? What is the MAC address associated to that IP address? | |
| S May 2, 2023 at 2:31 | review | First questions | |||
| May 2, 2023 at 4:10 | |||||
| S May 2, 2023 at 2:31 | history | asked | felipeek | CC BY-SA 4.0 |