Secure shell
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SSH is a protocol for secure remote access and file transfer that replaces insecure protocols like telnet. It uses encryption and authentication to securely transmit data, remote shell access, port forwarding, and file transfers between a client and server. Reasons to use SSH include enabling secure communication channels, arbitrary port redirection, optional compression, and protecting against spoofing and routing attacks.
Secure shell
- 1. • SSH is a protocol for secure remote access to a machine over networks which are not trusted • Created by Tatu Ylönen, a student of Helsinki University of Technology • SSH is a replacement for telnet, rsh, rlogin and can replace ftp • Uses Encryption • SSH is not a shell like Unix Bourne shell and C shell (wildcard expansion and command interpreter) • Transmission is secure • Transmission can be compressed Secure Command Shell Port Forwarding Secure file transfer Allow you to edit files View the contents of directories Custom based applications Create user accounts Change permissions Anything can be done from command prompt can be done remotely and securely SECURE SHELL
- 2. Port Forwarding Powerful Tool. Provide security to TCP/IP applications including e-mail, sales and customer contact databases, and in-house applications. Allows data from normally unsecured TCP/IP applications to be secured. Secure File Transfer Secure File Transfer Protocol (SFTP) is a subsystem of the Secure Shell protocol Separate protocol layered over the Secure Shell protocol to handle file transfers SFTP encrypts both the username/password and the data being transferred. Uses the same port as the Secure Shell server, eliminating the need to open another port on the firewall or router Using SFTP also avoids the network address translation (NAT) issues that can often be a problem with regular FTP An ideal use of SFTP is to fortify a server or servers outside the firewall or router accessible by remote users and/or partners (sometimes referred to as a secure extranet or DMZ).
- 4. Data Integrity Data integrity guarantees that data sent from one end of a transaction arrives unaltered at the other end. Even with Secure Shell encryption, the data being sent over the network could still be vulnerable to someone inserting unwanted data into the data stream. Secure Shell version 2 (SSH2) uses Message Authentication Code (MAC) algorithms to greatly improve upon the original Secure Shell's (SSH1) simple 32-bit CRC data integrity checking method. Data Encryption When a client establishes a connection with a Secure Shell server, they must agree which cipher they will use to encrypt and decrypt data. The server generally presents a list of the ciphers it supports, and the client then selects the first cipher in its list that matches one in the server's list. Encryption, sometimes referred to as privacy, means that your data is protected from disclosure to a would-be attacker "sniffing" or eavesdropping on the wire. Ciphers are the mechanism by which Secure Shell encrypts and decrypts data being sent over the wire.
- 5. Reasons to use SSH Arbitrary TCP/IP ports can be redirected through the encrypted channel in both directions The software can be installed and used (with restricted functionality) even without root privileges. Optional compression of all data with gzip (including forwarded X11 and TCP/IP port data), which may result in significant speedups on slow connections. SSH it is possible to create a secure communication channel between the server and the client. This channel can be used for different purposes, not necessarily for launching a remote terminal session but also for sending any data using the forwarding feature. SSH supports a variety of authentication methods, and new options may be added if required. Both the client and the server can authenticate each other to enhance security against different kinds of attacks. Protects Against: IPS Spoofing DNS Spoofing IP Source Routing