I am adding a new tcp port through ispconfig firewall. I have installed telnet apt-get install telnet and added port tcp 23 on firewall. I check ip tables and bastille firewall and the port shows in the output. Used nmap and can see the port in scan but if I telnet from the server command line it does not work. It supposed to connect to new app installed. App uses socket. Am I missing something. Phase 2 will be to configure stunnel for this but I would like phase 1 to work first before proceeding to stunnel. Thank you in advance.