What is "ssh"

In computer science, SSH (Secure Shell) is both a computer program and a network protocol that allow the connection to another computer on the network in order to allow the execution of commands from a Remote Unit. SSH is part of the TCP/IP protocol suite that makes remote administration of Unix-like servers secure. SSH has the same functionalities as TELNET, with the advantage of encryption in the connection between client and server. One of its best known applications is VPN with the tunnelling (tunnelling) technical strategy, which offers the ability to redirect data packets. For example, if someone is inside an institution whose Internet connection is protected by a firewall that blocks certain connection ports, it will not be possible, for example, to access emails via POP3 (via port 110) or send them via SMTP (via port 25 or 587). The two essential ports are 80 for HTTP and 443 for HTTPS. There is no need for the network administrator to leave multiple ports open, since unwanted connections that compromise the security of the institution can be established by them.

To break this rigid imposition, SSH offers the Tunnel feature. The process is characterized by two machines connected to the same SSH server, which only redirects requests from the computer that is under firewall. The user sends to the server a request for access to the pop.com server via port 443 (HTTPS), for example. Then, the server accesses the remote computer and requests access to the protocol, returning a set of packages related to the acquisition. The server encodes the information and returns it to the user via port 443. Thus, the user has access to all the information he needs. Such practice shall not be unlawful if the content flow is in accordance with the rules of the institution.