SCP is a secure file copy utility and SFTP is a secure file transfer protocol even though it does not have anything to do with the FTP we are use to in windows. 2 How can you use SSH to find out who is logged in on a remote system? By typing $ ssh host who in the terminal window
3 How would you use scp to copy ~/.bashrc file from the system named plum to the local system? From the local system you would type scp [email protected]:~/..bashrc local system: .bashrc. 4 How would you use scp to run xterm on plum and show the display on the local system? Having the same username on both systems and the X11 server running locally, the command to run xterm from the plum system and show on the local display is $ ssh plum xterm 5 What problem can enabling compression present when you are using ssh to run remote X applications on a local display? Compression can cause an increase in latency to an extent they might not be desirable for an X session forwarded over high-band width connections.
6 When you try to connect to another system using an OpenSSH client and you see a message warning you that the remote host identification has changed, what has happened? What should you do? This indicates that the fingerprint of the remote system is not the same as the local system remembers it. Check to find out if something changed. If everything is ok, get rid of the remote system’s key from the file located in the error message and try logging in on the remote system using ssh. Chap 20 pg 757
1 By default, email addressed to system goes to root. How would you also save a copy in /var/logs/systemmail? Edit the /etc/aliases that states: system: root, /var/logs/systemmail 2 How would max store a copy of his email in ~/mbox and sens a copy to [email protected]? $cat ~ Max/ .forward ~/mbox [email protected] \max
3 If your firewall allowed only the machine with the ip add of 192.168.1.1 to send email outside of the network, how would you instruct the local copy of sendmail to use this server as a relay? $ cat /etc/mail/access
Connect: 192.168 RELAY
4 What does dnl stand for in the m4 macro language? What are dnl commands used for? DNL stands for delete to new line, this token cause’s m4 to delete from the dnl to the end of the line. You can use this like the # command in the shell script. 5 SpamAssassin is installed on your mail server, with the threshold set to an unusually low value of 3, resulting in a lot of false positives. Which rule could you give to your mail client to allow it to identify spam with a score of 5 or higher? required_score 5.00
6 Describe the software and protocols used when Max sends an email to Sam on a remote Linux system.
a. Max’s MUA passes the email to sendmail.
b. The sendmail daemon uses SMTP to deliver the email to the instance of sendmail on Sam’s system.
c. On Sam’s system, sendmail passes the email to the local MDA (procmail). d. The MDA stores the email in Sam’s file in the spool directory. e. Sam’s MDA retrieves the email from the spool directory.