We have changed it a couple of times but some of them still get rcon...
And also they do this shit to us
"We tried to change rcon but they found out it again.
They are not just hacking our server, but they also fake our clan. They go to other servers to speedhack, ask for rcon and spam. They have (CAN) tag on, but they are not from (CAN). They are just silly kids that want to ruin our clan. I want to do something bout it. Please help me, give me any resolution to this shit."
you need the password. there is no other way. but you can use malware to get the password or sniff network packets (+decrypt them) to get the password. or you can somehow get access to the config file which contains the password.
make sure that all involved PCs are REALLY 100% safe and afterwards switch to a long random password. don't give the password to other people unless you are 100% sure that they are honest.
we can't really give more concrete help here because this seems to be a general security issue/breach in your system(s).
Actually, it's possible to make a scripted random rcon password generator, that would, say, generate a new "FJpd53zfgDL@"-like password each minute or 5 or 10. And maybe save a file or send a message to the admin when it's changed, and maybe make a command only admins (by USGN) can execute, like print me the rcon password.
yeah let's change the rcon password each minute - that's really convenient. That would mean that by the time you as admin have figured out what the rcon password is and have filled it in, it's already changed again.
Wouldn't the easiest way to get back your own server be to terminate it and/or restart it, assigning a new rcon password as you start your new server?
It has always worked for me. No one has really managed to hack my rcon passwords or stuff like that because I rarely give it out, although sometimes I give out the rcon password to MiroslavR and other peeps sometimes though.
Best thing would be to make a new rcon password every week/month or so, if you're obsessed with your own server's security that is.