Hello! I’m trying to ping some lemmy instances to understand which one is the faster, so I’m just using the ping command:
$ ping lemmy.ml
PING lemmy.ml (54.36.178.108) 56(84) bytes of data.
64 bytes from lemmy.ml (54.36.178.108): icmp_seq=1 ttl=49 time=24.4 ms
ping lemmy.world
PING lemmy.world (135.181.143.230) 56(84) bytes of data.
64 bytes from static.230.143.181.135.clients.your-server.de (135.181.143.230): icmp_seq=1 ttl=52 time=58.2 ms
but if I try with certain instances:
ping vlemmy.net
PING vlemmy.net (109.78.160.70) 56(84) bytes of data.
it just hangs there, forever. if I try to ctrl+C it, it displays
^C
--- vlemmy.net ping statistics ---
13 packets transmitted, 0 received, 100% packet loss, time 12267ms
why does this happens? I can perfectly visit vlemmy.net from my browser so I really can’t understand whay is this happening
what advantages can derive from this?
Prevents some types of port scanning normally. Don’t know about other advantages
ICMP is one vector of a distributed denial of service attack. Also, even if not denying the service, it puts load on the network interfaces / routers of that server - everything behind the first firewall / router layer that would otherwise block the ICMP requests.
Adding to the other answers, there isa bunch of server software that comes preconfigured to ignore ICMP.