This is a valid ipv4 address • Hacker News Board

Re: This is a valid ipv4 address

#51

Post by jloughry » Sun, Oct 20, 2013, 8:38 PM UTC

dreen wrote: post #17

Guys check out this website at http://0x7f000001 hahaha what an idiot made this, that page is shit!

You made a good point here: I recognised 127.0.0.1 in the value instantly, showing that you can sometimes read this representation by eye, e.g.:

    0x0a000001 = 10.0.0.1
    0xc0a80001 = 192.168.0.1

Re: This is a valid ipv4 address

#52

Post by rmrfrmrf » Sun, Oct 20, 2013, 8:46 PM UTC

The fact that this is 'news' or a 'trick' to some people says a lot about the current state of HN. IP addresses have integer representations by design! Are the commenters here really so removed from actually doing work that they've never seen a database that stores IP addresses as integers? (Hint: ALL of the good ones do). That's to say nothing of the fact that there are clearly many people here who don't understand what binary is.

At least it's good to know that the radical, ridiculous, Reddity mentality that's been plaguing HN as of late is coming from a clearly different group of people than those who used to comment. Looks like it's time to move on to greener pastures.

Re: This is a valid ipv4 address

#53

Post by nzmsv » Sun, Oct 20, 2013, 8:53 PM UTC

rachelbythebay wrote: post #46

300bps wrote: post #36

Earlier quoted context omitted.

That article is focused on ping and glibc but the reason why this works is fundamental to IPv4 itself. All IPv4 address are 32 bit addresses. That's why each number of an IPv4 address that people are familiar with are called octets. They represent 8 bits of the 32 bit address. So if you have 127.0.0.1, then the first octet is 127, the second is 0 and so on. Any representation of this 32 bit number (including the most…

No, it works because the tool allows it by virtue of how it's implemented. Find a different ping or inet_aton implementation and it won't necessarily work.

Interesting, I went searching and learned something new. You are right. Apparently the textual representation of IP addresses was not properly specified in any RFC, so this is in fact a quirk of the implementation.

http://tools.ietf.org/html/draft-main-ipaddr-text-rep-02

Re: This is a valid ipv4 address

#54

Post by jmduke » Sun, Oct 20, 2013, 8:54 PM UTC

rmrfrmrf wrote: post #52

The fact that this is 'news' or a 'trick' to some people says a lot about the current state of HN. IP addresses have integer representations by design! Are the commenters here really so removed from actually doing work that they've never seen a database that stores IP addresses as integers? (Hint: ALL of the good ones do). That's to say nothing of the fact that there are clearly many people here who don't understand…

I haven't been on Hacker News long enough to speak definitively about the current state of HN (a bit less than two years, but I spent the first one lurking), but I would be more concerned about comments that complain about 'HN changing' (as someone who was on Reddit to hear complaints about all the Diggers... then all the 4chaners.. then all the high schoolers..) than content considered 'elementary' to smarter programmers than I.

I notice that you haven't submitted any links. Is there any particular reason why? If you're not pleased with the content on the site, why don't you submit better content?

(For what it's worth: this content is news for me. I never spent much time thinking about IP addresses before clicking the link and getting confused for a solid minute. I understand what binary is, though, I promise!)

Re: This is a valid ipv4 address

#55

Post by wilg » Sun, Oct 20, 2013, 8:57 PM UTC

rmrfrmrf wrote: post #52

The fact that this is 'news' or a 'trick' to some people says a lot about the current state of HN. IP addresses have integer representations by design! Are the commenters here really so removed from actually doing work that they've never seen a database that stores IP addresses as integers? (Hint: ALL of the good ones do). That's to say nothing of the fact that there are clearly many people here who don't understand…

Almost all the other comments in this thread are people spreading knowledge about technology. Sure, maybe you already knew it. Maybe things were better "back in the day". People having a genuine interest in stuff like this just really doesn't seem worth bemoaning. Isn't it better to be happy that someone is learning something you're familiar with rather than being upset that they didn't already know it?

Re: This is a valid ipv4 address

#56

Post by bloometal » Sun, Oct 20, 2013, 9:07 PM UTC

nwh wrote: post #5

The decoded URL for this submission is http://184.172.10.74/ — the server for Hacker News. Here's some other encodings you can use for the same address, they're all valid and recognised by most browsers and other software: http://3098282570/ http://7393249866/ http://0xb8.0xac.0x0a.0x4a/ http://0270.0254.0012.0112/ The source for this comment is an XSS filtering bypass tool by RSnake — http://ha.ckers.org/xsscalc.htm…

Went to RSnake's website and encoded the address of Facebook to post on my wall. Facebook does not let me post it. After 3 or 4 tries, it blocked my account.

Does anyone know why Facebook does that?

Re: This is a valid ipv4 address

#57

Post by zymhan » Sun, Oct 20, 2013, 9:14 PM UTC

seanalltogether wrote: post #30

It took me awhile to understand what was so significant about the submission. In chrome when I roll over the link i just see 184.172.10.74.

Interesting, when I roll over it in Firefox I see the large number.

Re: This is a valid ipv4 address

#58

Post by Perseids » Sun, Oct 20, 2013, 9:18 PM UTC

rmrfrmrf wrote: post #52

The fact that this is 'news' or a 'trick' to some people says a lot about the current state of HN. IP addresses have integer representations by design! Are the commenters here really so removed from actually doing work that they've never seen a database that stores IP addresses as integers? (Hint: ALL of the good ones do). That's to say nothing of the fact that there are clearly many people here who don't understand…

Even though I know that IP addresses are just 32 bit of data I find it very interesting that browser support these representations out of the box. There is no reason to and from a security point of view it is even detrimental.

Re: This is a valid ipv4 address

#59

Post by icedchai » Sun, Oct 20, 2013, 9:20 PM UTC

bloometal wrote: post #56

nwh wrote: post #5

The decoded URL for this submission is http://184.172.10.74/ — the server for Hacker News. Here's some other encodings you can use for the same address, they're all valid and recognised by most browsers and other software: http://3098282570/ http://7393249866/ http://0xb8.0xac.0x0a.0x4a/ http://0270.0254.0012.0112/ The source for this comment is an XSS filtering bypass tool by RSnake — http://ha.ckers.org/xsscalc.htm…

Went to RSnake's website and encoded the address of Facebook to post on my wall. Facebook does not let me post it. After 3 or 4 tries, it blocked my account. Does anyone know why Facebook does that?

Probably because this "trick" is often used by spammers to obfuscate URLs.

Re: This is a valid ipv4 address

#60

Post by memracom » Sun, Oct 20, 2013, 9:24 PM UTC

An IPv4 address is a 32 bit string of bits. That 32 bit value can be represented in many different ways, but none of those ways are IPv4 addresses. The actual address is that string of 32 bits, and that is what is used in the TCP stack inside your OS or your router.