The Secure Shell ORAFACT Secure Shell Replaces unencrypted

The Secure Shell ORAFACT

Secure Shell Replaces unencrypted utilities • rlogin and telnet • rsh • rcp Automates X 11 authentication Supports tunneling of other protocols • POP, IMAP • HTTP • PPP Supports user RSA/DSA keys for password-less logins ORAFACT

ssh and sshd Configuration Server daemon – sshd • /etc/sshd_config The main configuration file for sshd. Lists which features will be supported (Protocol, X 11 Forwarding, Permit. Root. Login, Compression, Cihpers, etc). The 50+ supported options are well described in the man page sshd_config(5). • /etc/ssh_host_key{, . pub} The private and public keys that the server uses. These are normally created the first time sshd is started, and are used during the host authentication process. • /etc/sshrc Contains a list of commands that the SSH server should execute when an SSH client connects. These commands are run for all users just before the shell is started. • . /. ssh/rc (no longer normally used) Same use as the global /etc/sshrc file, but specific to a user. ORAFACT

ssh and sshd Configuration Secure Shell Client – ssh • /etc/ssh_config The main configuration file for the SSH client commands. Lists which features will be requested or supported (Protocol, Compression, Cihpers, Number. Of. Password. Prompts, etc). The 50+ supported options are well described in the man page ssh_config(5). • . /. ssh/config Same use as the global /etc/ssh_config file, but specific to a user. • . /. ssh/id_{rsa, dsa}{, . pub} User specific public and private keys that are used when attempting key-based authentication. • . /. ssh/known_hosts ORAFACT

Accessing Remote Shells Encrypted Logins • ssh user@host - remote interactive login • ssh user@host command - remote non-interactive command execution Escape Sequences An escape sequence is a key sequence that tells SSH to send a specific control message or switch to another mode. • ~. which quickly closes the connection • ~? which prints a list of available escapes. ORAFACT

Transferring Files Encrypted File Transfers • sftp - interactive file transfer ($ sftp guest@of 4 ) • scp - non-interactive file transfer ($ scp /etc/passwd guest@of 4: /tmp Alternative sftp Clients Command-line sftp Interfaces • lftp • mc Graphical sftp Interface • konqueror • nautilus ORAFACT