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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

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Why can't I ping some websites? (self.linux)

submitted 1 year ago by tubbadu to c/[email protected]

33 comments fedilink hide all child comments

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

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[–] [email protected] 22 points 1 year ago (2 children)

One possibility is that the server is configured not to respond to pings

[–] worldofbirths 2 points 1 year ago

This is most likely the issue. Maybe just measure HTTP response times instead?

[–] tubbadu 1 points 1 year ago (5 children)

what advantages can derive from this?

[–] SirMrR4M 7 points 1 year ago

Prevents some types of port scanning normally. Don't know about other advantages

[–] raspberriesareyummy 7 points 1 year ago (1 children)

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.

[–] tubbadu 2 points 1 year ago

okay I get it, thanks!

[–] [email protected] 3 points 1 year ago

honestly, not much... other than warm and fuzzies for the person doing the blocking. ICMP sweeps are quick and cheap, so it stops a host from being found easily, but there are other ways to find abhost that are just as easy and cheap.

[–] [email protected] 2 points 1 year ago

Adding to the other answers, there isa bunch of server software that comes preconfigured to ignore ICMP.

[–] [email protected] 2 points 1 year ago

I think we block everything that's unecessary, to minimise any attack surface area