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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).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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Why can't I ping some websites? (lemmy.world)

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

26 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] 1 points 1 year ago (5 children)

what advantages can derive from this?

[–] [email protected] 5 points 1 year ago

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

[–] [email protected] 4 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.

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

okay I get it, thanks!

[–] [email protected] 2 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