Hello,
i was reading some tutorials about arduino as HTTP server and stuff like this and i want to ask if arduino can use other protocols like telnet or FTP…. if there is some libraries for that so i can for ex. communicate with it via telnet, SSH or i can just manage or download some data from storage like sd card connected to arduino via FTP.
Thank you for response 
Although there are some implementations of the FTP protocol for Arduinos in my opinion this makes no sense. Use a Raspberry Pi (or any similar Linux board) if you want to use different network servers. Arduinos are perfect to connect a multitude of hardware (sensors, actors, etc.) but all server implementations are crutches at best.