Linux: Domain Name System and Server Essay

Submitted By mizznicole
Words: 4882
Pages: 20

Note that this is BEFORE you have even loaded your applications, which is why most people use a computer - the applications. linux Networking Services Printing with CUPS Unix Printing Utilities: LPD and LPR CUPS Cross Platform built around IPP Used on Linux, Windows, Unix, Mac OSX IPP HTTP-based client/server protocol - started in 1996 by Novell et. al. Determines capabilities of printer Submits jobs to printer Determine the status of a printer Determine the status of a print job Cancel a print job Pre-Requisites cups system-config-printer cups-pdf (optional) Configuration GUI (system-config-printer) Web Interface Firewall TCP Port 631 Network Printing Server (IPP) = Trusted Service Printing with CUPS. SSH = Secure Shell Suite of secure networking tools ssh – login and run commands on a remote computer scp = Secure copy – good for transferring files to/from remote computers sftp – Securely transfer files to/from remote computer – Secure replacement for sshd – Daemon (or service) that allows for ssh connection All traffic is encrypted SSH2 protocol – improved security, performance and portability over SSH1 X11 forwarding When enabled, the remote server’s desktop is visible to the user When might this be a bad idea? Uses a host key pair and a session key to negotiate an encrypted session Host key pair – Set of public/private keys Established automatically when ssh is run for the first time Session Key – Symetric key that client and server share The first time you connect, it verifies that the client is connected to the right server This prevents “Man-in-the-Middle” attacks. After verification, client makes a copy of the server’s public host key On su sequent visits, client compares Server’s public host key and compares it to what was stored the first time.Next, the client generates a random key Creates an encrypted key using the server’s public host key and the session key Client sends this to the server Server decrypts encrypted key with it’s private key. /etc/ssh ssh_config – Global config file sshd_config – Config file for the sshd daemon (service) ssh_known_hosts – makes remote systems available to all users
/home//.ssh config – user’s ssh config file – overrides the Global config file known_hosts – contains public keys of hosts the user has connected to Installation Log in as root (su -) yum -y install openssh openssh-clients Configuration ssh Usage ssh [options] user@host [command] Connect to remote system using the same login name sftp Usage Replaces ftp by mapping the ftp commands to OpenSSH commands sftp will add your connection to the known_hosts file sftp Commands cd – change directory on the sftp server lcd – change directory on your local machine ls – lists files in current directory on the sftp server lls – lists files in current directory on your local machine pwd – print working directory on the sftp server lpwd – print working directory on your local machine exit – exits the sftp program. sftp Commands (cont…) sftp will add your connection to the known_hosts file get – transfer a file from the sftp server to your local machine mget – transfer multiple files from the sftp server to your local machine put – transfer a file from your local machine to the sftp server help or ? – Shows a list of all sftp commands. ssh, scp and sftp Configuration Files Rarely need modification (2) Configuration files User - home//.ssh/config Global - /etc/ssh/ssh_config sshd reads them in the order of user, then global and uses the first directive that is found Therefore, the user file can override the global file Interesting Parameters ForwardX11 (yes/no) – When set to yes, it automatically forwards X11 desktop over ssh connections. Used with ForwardX11Trusted ForwardX11Trusted – when both are set to yes, it gives X11 clients full access to the server X11 display. Host – specifies declarations that apply to all hosts being connected to User – Specifies a username to log onto the server with – Lists the names of files cat –