Скачать или смотреть Call same IP address in 15+ different ways. 127.0.0.1, localhost, 0.0.0.0, 127.1, 0x7f.1, 0177.1 etc

One IP, different ways of representation

. Do you know you can call API / IP address with more than 15+ ways?
. One IP ~ many ways of representation
. Using localhost,
. Using different number systems - decimal, hex, binary, octal, url encoding, mixed number system: hex with decimal etc.
. Hacker can use any 1 of these notations?
. Are you/your server is safe?

Generally we write IP address in decimal number system with dot notation. But same Ip can be written using different number systems say hex, binary, octal with dot notation and without dot notation and we can mix number systems also while writing ip addresses.

Links
https://www.hacksparrow.com/networkin...
Hussein Nasser -    • Why 0177.0.0.1 is also localhost  


======================= examples========
✅️ - localhost

============= decimal - dot notation
✅️- http://127.0.0.1:3000 // o-255
✅️- http://127.000.000.001:3000 // o-255
✅️- http://0.0.0.0:3000 // o-255

✅️- 127.00000000.00000000.000000001 // except leftmost, all other can be left padded with many zero's but left padded zero is of no value

❌️- 00127.0000.00000.00001 // here left most part is 0127 which means its octal representation which in turn is 87.0.0.1 in decimal

✅️- 127.1 // 0 optimized
✅️- http://0:3000
✅️- http://000000000000000000000:3000


============= decimal to octal
// for octal representation we have to prefix number with 0

✅️- 127.0.0.1 = 0177.0.0.1 // 127 in octal is 0177

✅️- 127.00000000.00000000.000000001 = 0177.00000000.00000000.000000001
00000000000000000177.00000000.00000000.000000001
0177.0.0.0000000000000000001

✅️- 127.1 = 0177.01
000000000000000000000000177.000000000000000000000001

✅️- http://00:3000 // o-255

============= decimal to hex
// for hex representation we have to prefix number with 0x

✅️- 127.0.0.1 = 0x7f.0x0.0x0.0x1 // 127 in hex is 7F

✅️- 127.00000000.00000000.000000001 = 0x7f.0x00000000.0x00000000.0x000000001
X 000000000000000000x7F.0x0000000.0x0000000.0x00000001
✅️0x7F.0x0.0x0.0x000000000000000001

✅️- 127.1 = 0x7F.0x1
✅️- http://0x0:3000
✅️- http://0x0.0x0.0x0.0x0:3000
✅️- http://0x000000000000000000:3000

✅️- 0x7f000001 - in case of hex values, dot notation is optional
❌️- 0x7f01
❌️- 0xabCDFE7F000001 - Any random hex chars can be prefixed, it get resolved to 0x7F00001


============= decimal to binary
// for binary representation we have number 0 and 1 only, binary works ✅️ with ping command, not ❌️ working with curl and browser

❌️- 127.0.0.1 = 01111111000000000000000000000001

❌️- http://0b1111111.0b0000000.0b0000000.0b0000001:0b101110111000
❌️- http://1111111.0000000.0000000.0000001:101110111000


// url encoded
http://%31%32%37%2E%30%2E%30%2E%31:3000 = http://127.0.0.1:300 // this works on browser, not curl

// mixed
00000000000000000000000000000000000000000000000000177.1 // octal and decimal
✅️- 0x7f.1 // hex and decimal
✅️- 127.0x1 // decimal and hex
✅️- 0x7F.01 // hex and octal
❌️- 01111111.0x1 // binary and hex