[Aachen]

I'm interested in the topic so skimmed the whole thing but it's all just basics. Most people won't know them all, but so FYI: skip the lengthy article if you know how traceroute and ARP and ICMP work in general, what the difference is between connection times out and connection refused, and why sometimes traceroute returns more than one host for a given hop.

[Hikikomori]

I wouldn't call the details he goes into with traceroute "just basics", its common even for network engineers to come to the wrong conclusion based on traceroute output, or not realising that they need more information to truly know what is going on (traceroute from both sides).

[csydas]

I would second this. I handle a lot of meetings and screenings for technical positions and quite a few Senior Network Administrators don't know or remember the basics for a lot of networking items and are completely lost when it comes to items like this. It is very much so a prevalent problem that many IT persons don't realize it's not only possible, but common to block ICMP entirely. For me, this has rendered ping unreliable as I can never truly know if we really can't reach the host or if some Network Security Admin has blocked ICMP (and often the Network persons aren't aware of this either).

Same with traceroute -- it's a common question in our interviews, "if you suspect a poor route in a given topology, which servers (client, server) should you run traceroute on?". The most common answer is just the client, without a lot of understanding that you have to consider the route from the server to the client and, like the article shared, that you only get the route info from the server you test.

Networking is still pretty tough I would say and a lot of support tickets raised for my company's product are 100% related to the network in the environment, but the Network Admin/Team lacks the depth to really investigate such issues, but knows enough to at least try to argue it's not network.

I love articles like this which clearly and plainly discuss the basic elements of networking because how you understand the basic elements fundamentally shapes how you understand network errors. The number of conversations I've had with clients who when faced with an error like "Host refused connection" when our product can't connect to a host ask with a straight face "so why did your application close the connection?" is far too high, and it's pretty disappointing on a personal level to have such discussions. Ignorance is not a sin. Reveling in ignorance is.

[nickstinemates]

ICMP blocking is a very common thing. Thus tcping was born.

If you want to do any of these types of operations from Rust, you can use https://docs.rs/netdiag/latest/netdiag/. It's very good.