Just out of curiosity, does the DVR offer something called “XMEye P2P Cloud” to view video images remotely?
If so, you might want to read this
As ukhardy07 states, telnet isn't secure and should never be used for remote access. FTP is also completely insecure. SSH may
be more secure but not all implementations of SSH are secure. You may also have a password which is weak or the device may have a hardcoded default admin password which cannot be changed.