Remote Connectivity

The Saigon CTT Remote Connectivity The Saigon CTT  Objectives  Explain : telnet rsh ssh  Configure FTP The Saigon CTT  Telnet  Telnet is used to communicate to a host through telnet protocol on default port 23  It operates on client/server basic The client requires an account on the server to login  Most telnet servers will not allow you login as root because of security You can login as normal user and su to root The Saigon CTT  Telnet  telnet is insecure protocol : username and password send from client to server across network in clear text  why people still use it ? - telnet can be used for debugging text based protocol : HTTP, SMTP and POP The Saigon CTT  Relevant File - ~/.telnetrc  When users has telnetrc file in their home directories, telnet will execute the commands listed in this file # this is a comment saigonctt send ayt DEFAULT environ export USER The Saigon CTT  Telnet Commands  Command Format : telnet [IP address|host name] [port]  If telnet is executed without options, it will be started in command mode with prompt “telnet>”  You can change to command mode by “Ctrl-]” after connected The Saigon CTT  Telnet Commands ?, h, help Lists commands with description ? More information of command (arg) open Open connection to the IP address or host name close = quit Terminates connection from client logout Requests server to terminate the connection send Send a special character sequence to the server status A brief status report of telnet … ( See #man telnet for more commands ) The Saigon CTT  The r Commands  There are programs : rlogin Remote login rsh Remote shell executes command rcp Remote copy  Password NOT required if following files are configured: /etc/hosts.equiv (system-wide) $HOME/.rhosts (per-user) ( Entry : [+|-] [hostname] [username] ) The Saigon CTT  The r Commands  rlogin : similar to telnet rlogin [-l username]  rsh : executes cmd on remote host rsh [-l username] Shell meta-characters can be used in To have rsh interpret the meta-characters on remote machine, put `quotation mark around them If not quotes,metacharacters are interpreted on local machine : # rsh –l minh saigonctt “cat ~/file” > local_file # rsh –l minh saigonctt “cat ~/file” “>” remote_file The Saigon CTT  The r Commands  rcp : copy files between machines rcp @: rcp @:  Example : rcp /home/file minh@saigonctt:/backup rcp minh@saigonctt:/backup/file /home rcp -r /etc minh@saigonctt:/backup/etc rcp –p /etc minh@saigonctt:/backup/etc The Saigon CTT  Component of SSH2 sshd2 Server ssh2 Client sftp-server2 SFTP Server (executed by sshd2) sftp2 scp2 SFTP Client (need ssh2) Sercure copy files, replaces rcp The Saigon CTT  Component of SSH2 ssh-keygen2 The utility for generating keys ssh-agent2 Authetication agent, used to hold RSA keys for authentication ssh-add2 Add identifier to the authentication agent ssh-askpass2 X11 utility for querying password The Saigon CTT  SSH2 Changes  SSH has been 98% rewritten  Supports other key-exchange methods besides RSA : Diffie-Hellman key exchange  Supports for DSA and other public key algorithms besides RSA The Saigon CTT  SSH2 Changes  New added features : sftp , the secure file transfer protocol  More secure and allows integration into public key infrastrures  Supports “subsystems”, platformindependent module, built-in SOCKS, … The Saigon CTT  Install SSH1 – from OpenSSH  Because of legal reasons, SSH is not included by default in Linux You can download and install from source code or from OpenSSH  OpenSSH suite includes : • ssh (replaces telnet and rlogin) • scp (replaces rcp) • sftp (replaces ftp) The Saigon CTT  Install SSH1 – from OpenSSH  Server : openssh-server-xxx.rpm (sshd, sshd_config, sftp-server, )  Client : openssh-clients-xxx.rpm (ssh, ssh_config, sftp, )  Addtion tools : openssh-xxx.rpm (scp, ssh-keygen, ) ... commands ) The Saigon CTT  The r Commands  There are programs : rlogin Remote login rsh Remote shell executes command rcp Remote copy  Password NOT required if following files are configured:... minh saigonctt “cat ~/file” “>” remote_ file The Saigon CTT  The r Commands  rcp : copy files between machines rcp @: rcp @:...  rsh : executes cmd on remote host rsh [-l username] Shell meta-characters can be used in To have rsh interpret the meta-characters on remote machine, put `quotation