Changes

To preempt some confusion let's start You should have learned in OPS235 how to view existing iptables rules with the command: iptables -L.Although you may assume that this: listing of rules should be empty, they may not be! There might be default rules that already exist, or that exist when the firewall is reset to default (i.e. iptables -F). In fact, several rules are were '''automatically added for ''' to your chains because you because of the are using a '''virtual network'''. As an exercise , wewill determine which of those rules when running a virtual network were added. ''ll figure out what those are exactly'Perform the Following Steps:'''# Run '''iptables -L''' and but redirect the output to a text file, so called '''before.txt''' (you can refer to it will be using this file later).# Shutdown all of your VMs.# Stop the '''libvirtd ''' service# Restart the '''iptables ''' service# Rerun Re-issue '''iptables -L''' commands making certain to redirect output to get a second file ('''after.txt'''). This should provide a listing of the new state of the your firewall and redirect the output to settings. Use a second text different, but an appropriate file-name.# Now you You now should have two text files representing the <u>before </u> and <u>after </u> states of your firewall. You can compare Compare differences between these two files using the files visually but it's often easier to use a diff command (You should have used this tool:#* in ULI101). The command-line tool '''diff''' takes some time to get used to but you'll get used to it eventually, it's used a lot in the industry. #Run '''diff -u before.txt after.txt''' and figure out how to read the output.#* <br><br>'''TIP:''' You can also install a graphical tool that makes it much easier to see differences: '''kompare before.txt after.txt'''<br><br>