cobusbernard/Networking

## Networking
1) if you’re on (most modern distributions of) linux, forget that `route(1)` even exists (and throw `ifconfig` out in the same go) because it’s just absolutely frustrating. for probably 98% of what you need, `ip(1)` is the cool you care about
generally speaking, these will cover you: `ip route`, `ip address`, `ip link`
2) when dealing with routing problems (*even if just two hosts next to each other*), `mtr` > `traceroute` > `ping` is an order that’s useful for a lot of what you need
mtr is nice because you can just let it keep running. press `d` in its display to get a running history breakdown of packets. fantastic for intermittent issues!
traceroute is generally known already, but depending on the complexity of your networks in question you may want `traceroute-nanog` or similar other ones. some of these are ASN-aware, which is useful.
in the same breath as traceroute, something else that’s useful to know about is `tracepath`
it’s a little bit nicer on finding asymm paths
lastly, `ping` *is* still useful in this, but if you need to start forcing specific kind of pings (pinning a specific source address, forcing a specific source interface, etc), sometimes `fping` can be slightly easier, so do be aware of it as well
oh and re tcpdump, a small gotcha to also be aware of: if you do something like `tcpdump -nvi any -s 0 ….[filters here]…`, you can get weird MAC stuff because of it capturing in promiscuous mode.
	1) if you’re on (most modern distributions of) linux, forget that `route(1)` even exists (and throw `ifconfig` out in the same go) because it’s just absolutely frustrating. for probably 98% of what you need, `ip(1)` is the cool you care about
	generally speaking, these will cover you: `ip route`, `ip address`, `ip link`
	2) when dealing with routing problems (even if just two hosts next to each other), `mtr` > `traceroute` > `ping` is an order that’s useful for a lot of what you need
	mtr is nice because you can just let it keep running. press `d` in its display to get a running history breakdown of packets. fantastic for intermittent issues!
	traceroute is generally known already, but depending on the complexity of your networks in question you may want `traceroute-nanog` or similar other ones. some of these are ASN-aware, which is useful.
	in the same breath as traceroute, something else that’s useful to know about is `tracepath`
	it’s a little bit nicer on finding asymm paths
	lastly, `ping` is still useful in this, but if you need to start forcing specific kind of pings (pinning a specific source address, forcing a specific source interface, etc), sometimes `fping` can be slightly easier, so do be aware of it as well
	oh and re tcpdump, a small gotcha to also be aware of: if you do something like `tcpdump -nvi any -s 0 ….[filters here]…`, you can get weird MAC stuff because of it capturing in promiscuous mode.