Certification Basic Networking Clients UNIT 17 Basic Networking Clients 1 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. UNIT 16: Objectives ? Learn basic network commands ? Learn how to communicate securely with remote hosts ? Understand the use of rsync and wget 2 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. UNIT 17: Agenda ? ssh / scp / telnet ? lftp ? links ? mutt ? rsync / wget ? ping / traceroute / host 3 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. ssh: Secure Shell ? Public-key encryption technology replacement for various unsecure services ? Allows secure access to remote systems · $ ssh joe@barney -or- · $ ssh -l joe barney joe@barney's password: · $ ssh barney ls /tmp 4 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. scp: Secure copy ? Secure replacement for rcp ? Layered on top of ssh · $ scp source destination ? Remote files can be specified using: · user@host:/path/to/file · -r option enables recursion · -p preserves times and permissions · -C compresses datastream 5 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. telnet and the “r” services ? Insecure protocols ? telnet: Login names and passwords pass over the network in clear text ? “r” services (rsh, rlogin, rcp): generally insecure authentication mechanism ? telnet client can be used to connect to services running on arbitrary ports ? Example: testing your mail server: $ telnet localhost 25 6 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. lftp ? Versatile command-line FTP client ? Anonymous or real-user sessions $ lftp ftp.cdrom.com $ lftp -u joe ftp.myserver.com ? Automated transfers with lftpget 7 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. links Web Client ? links – text based web client ? Very fast compared to graphical clients ? Disregards graphics ? Frames and tables capable ? Can work non-interactivelyCharacter based web browser · links http://www.redhat.com 8 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. mutt ? Character based email client ? Powerful attachment handling ? Supports various mailbox formats ? Provides threaded reading of messages 9 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. rsync ? A drop-in replacement for rcp for copying to or from remote systems ? Can use ssh for transport $ rsync --rsh=ssh mysong.mp3 barney:/home/joe/ ? Faster than scp - copies differences in like files 1 0 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. wget ? Retrieves files via HTTP and FTP ? Non-interactive - useful in shell scripts ? Can follow links and traverse directory trees on the remote server - useful for mirroring web and FTP sites 1 1 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. Network Diagnostic Tools ? ping ? traceroute ? host ? dig ? netstat 1 2 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc. End of Unit 17 ? Questions and answers ? Summary · Learn basic network testing and troubleshooting commands · Examine the use of secure network clients · Understand the use of rsync 1 3 Rev RH033-RHEL3-1 Copyright © 2003 Red Hat, Inc..