Hex value of ip address why reversed?

wsxdrfv

jr. member

Activity: 413

Merit: 5

Quote from: bob123 on March 11, 2018, 04:32:32 AM

Quote from: wsxdrfv on March 11, 2018, 03:03:02 AM

If my real IP address is 175.126.37.238 and this address should be input above, then 0xee257eaf is correct? Internet site hex to ip
https://www.browserling.com/tools/hex-to-ip
shows this 0xee257eaf is 238.37.126.175

This is due to Endianness (https://en.wikipedia.org/wiki/Endianness).

When communicating via a network, you don't know how your counterparty is 'reading' the values.
Most significant bit at the most left or most right position?

Big-endian (most significant byte has the lowest address [left-to-right reading]) is also referred to network byte order.
Depending on the system you are using your pc might use big- or low- endian format. But when communicating via network, always big endian is used (IPv4/6, TCP/UDP).

Thats the reason for the mysterious reverse order.

I don't know Endian well, but perfect description.

bob123

legendary

Activity: 1624

Merit: 2481

Quote from: wsxdrfv on March 11, 2018, 03:03:02 AM

If my real IP address is 175.126.37.238 and this address should be input above, then 0xee257eaf is correct? Internet site hex to ip
https://www.browserling.com/tools/hex-to-ip
shows this 0xee257eaf is 238.37.126.175

This is due to Endianness (https://en.wikipedia.org/wiki/Endianness).

When communicating via a network, you don't know how your counterparty is 'reading' the values.
Most significant bit at the most left or most right position?

Big-endian (most significant byte has the lowest address [left-to-right reading]) is also referred to network byte order.
Depending on the system you are using your pc might use big- or low- endian format. But when communicating via network, always big endian is used (IPv4/6, TCP/UDP).

Thats the reason for the mysterious reverse order.

wsxdrfv

jr. member

Activity: 413

Merit: 5

Quote from: tspacepilot on March 10, 2018, 02:39:30 AM

I admit that I'm not exactly sure what your context is or what you're looking at, but over the wire, IP addresses are encoded in big-endian format.

If that's the kind of 'reversal' you're talking about, then I suggest you take a look at:

Code:

$ man 3 htons

so at net.cpp, unsigned int pnSeed[] = { 0xee257eaf }

If my real IP address is 175.126.37.238 and this address should be input above, then 0xee257eaf is correct? Internet site hex to ip
https://www.browserling.com/tools/hex-to-ip
shows this 0xee257eaf is 238.37.126.175

Anti-Cen

member

Activity: 210

Merit: 26

High fees = low BTC price

Quote from: tspacepilot on March 10, 2018, 02:39:30 AM

but over the wire, IP addresses are encoded in big-endian format.

here is the code that works with DNS A-Record lookup for Ipv4

Code:

private static byte[] DnsBytesReverseLookup(string IP)
   {//Builds up a request for a Reverse DNS-Lookup
   byte[] Head = SeedTheHead(DateTime.Now.Minute);
   byte[] Footer = new byte[18] { 7, 105, 110, 45, 97, 100, 100, 114, 4, 97, 114, 112, 97, 0, 0, 12, 0, 1 };//in-addr.arpa
   string[] IPDigits = IP.Split('.');
   MemoryStream MS = new MemoryStream();
   MS.Write(Head, 0, Head.Length);
   byte[] IP0 = ByteString(IPDigits[0]); byte[] IP1 = ByteString(IPDigits[1]); byte[] IP2 = ByteString(IPDigits[2]); byte[] IP3 = ByteString(IPDigits[3]);
   MS.Write(IP3, 0, IP3.Length); MS.Write(IP2, 0, IP2.Length); MS.Write(IP1, 0, IP1.Length); MS.Write(IP0, 0, IP0.Length);
   MS.Write(Footer, 0, Footer.Length);
   return MS.ToArray();
   }

private static byte[] ByteString(string Value)
   {//Used to build up a DNS request
   byte[] B = new byte[Value.Length + 1];
   B[0] = (byte)Value.Length;
   B[1] = (byte)Value[0];
   if (Value.Length > 1)
   B[2] = (byte)Value[1];
   if (Value.Length > 2)
   B[3] = (byte)Value[2];
   return B;
   }

The order is backwards but it's not hex

tspacepilot

legendary

Activity: 1456

Merit: 1081

I may write code in exchange for bitcoins.

I admit that I'm not exactly sure what your context is or what you're looking at, but over the wire, IP addresses are encoded in big-endian format.

If that's the kind of 'reversal' you're talking about, then I suggest you take a look at:

Code:

$ man 3 htons

Anti-Cen

member

Activity: 210

Merit: 26

High fees = low BTC price

I tested 10.11.12.13 and got 0a.0b.0c.0d so it looks fine to me but why anyone
wants to store ip's hex seems strange to me but often ips are converted to longs so that you
can write code like

if (IP>=12334567 && IP<=89101112)
do something with range.

wsxdrfv

jr. member

Activity: 413

Merit: 5

net.cpp's [ pnSeed ] variable, there are hex value of ip address.

Is it reverse of ip address?

Why its result and this site's result is reverse?

https://www.browserling.com/tools/ip-to-hex

Topic: Hex value of ip address why reversed? (Read 219 times)