I'm probably going to get downvoted to hell but I have to ask: Can someone please explain? I'm perpetually trying to expand my knowledge on the technical side of Linux.
linuxmemes
Hint: :q!
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This is the behaviour of inet_aton, which ping uses to translate ASCII representations of IPv4 addresses to a 32 bit number. Its manpage: https://man7.org/linux/man-pages/man3/inet_aton.3.html
It recognizes the usual quad decimal notation of course, but also addresses of the form a.b.c or a.b, or in this instance, a, with is taken to be a 32bit number.
Each part can also be written in hex or octal, with the right prefix, such that 10.012.0x800a is as valid form for 10.10.128.10.
Not all software use inet _aton to translate ASCII addresses. inet_pton for instance (which understands both v4 and v6) doesn't
An IP address is a 32-bit number, usually expressed as four 8-bit numbers separated by dots. Converting 33333333 to hex we get 01FCA055; splitting that into pairs and converting back to decimal gives 1, 252, 160, 85.
Typically an IP address is represented as 4 8-bit integers (1.252.160.85), but it can also be represented as a single 32-bit integer (33333333). The ping
utility accepts both forms.
Best ping is 127.0.0.1
It always resolves!
Try pinging 127.1 - it is the same, but shorter.
Just another tipp from someone who learned TCP/IP from reading the sources over three decades ago...
even shorter: ping 0
This is a special case. This resolves to 0.0.0.0, and technically cannot be routed. Some(!) systems use it as a kind of alias for all local network addresses, but it is not a given.
I'm aware. Conveniently this works on all the systems I've tried, making it useful for testing local services (e.g. ssh 0
).
Fun fact 127.0.0.1-127.255.255.254 is all localhost
Pretty insane that around 0.4% of all IPv4 addresses are wasted.
Wayyyyyy more than that is wasted.
What about 127.255.255.255 ?
That is a broadcast address
Does the loopback broadcast address behave differently from any other of the loopback addresses?
Superior Ping:
ping 1.1
also works. It resolves to 1.0.0.1, which is Cloudflare's secondary DNS
For those who are still confused, ping works with 32 bit unsigned integers. While there certainly are more uses, it's a much more convenient method for storing IP address in a database as it's easier to sort and index than 4 numbers separated by 4 periods
http://www.aboutmyip.com/AboutMyXApp/IP2Integer.jsp?ipAddress=1.1.1.1
it's so simple!
ping -c 4 $(mysql -u frodo -p keepyoursecrets -D /home/pingtargets.db -se "SELECT ip FROM servers ORDER BY RAND() LIMIT 1;")
I prefer:
ping 133742069
(probably lands you on a list tho...it's a US DoD IP)
I fondly remember regularly logging into simtel20.wsmr.army.mil back in the days (WSMR=White Sands Missile Range). No issue, just used "anonymous" as the username, and your email address as the password. And even the email address was just a convenience...
55555555
All addresses that that start in 555
were left open by the internet protocol developers just for movies and TV shows.
And the ones starting with 800 are for Pay Per View?
Or, if you're me,
$ ping 16843009
PING 16843009 (1.1.1.1) 56(84) bytes of data.
64 bytes from 1.1.1.1: icmp_seq=1 ttl=53 time=4.06 ms
64 bytes from 1.1.1.1: icmp_seq=2 ttl=53 time=4.04 ms
64 bytes from 1.1.1.1: icmp_seq=3 ttl=53 time=4.05 ms ^C
***
16843009 ping statistics
***
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 4.044/4.053/4.062/0.007 ms
Ping ::1
ping 9.9.9.9
It's 1111 higher.