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| − | [[Category:OPS335]][[Category:OPS335 Labs]] | + | #REDIRECT [[OPS335_Lab_2]] |
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| − | ==IPTABLES - The Linux firewall==
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| − | In this lab you will learn how to use iptables to build a simple Linux firewall.
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| − | ==Instructions==
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| − | ===Building a Simple Firewall===
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| − | *Login as joker to your Fedora 13 PC.
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| − | **It's not necessary to use a VM for this lab. Just use your original Fedora system created in lab #0.
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| − | *Open a terminal window and "su -" to root.
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| − | *Disable your current firewall. i.e. flush all rules in all chains in all tables.
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| − | Build a custom firewall by performing the following steps:
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| − | #Add appropriate rule(s) to allow all traffic to/from the loopback 'lo' interface.
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| − | #Add a rule to the INPUT chain of the filter table to allow all UDP traffic coming from port 53. i.e. source port is 53.
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| − | #Add a rule to the INPUT chain of the filter table to allow all ESTABLISHED or RELATED incoming connections.
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| − | #Create a new chain named MYSSH in the filter table.
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| − | #Add a rule to the INPUT chain of your filter table that sends all tcp packets with destination port 22 to your MYSSH chain.
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| − | #Add a rule to your MYSSH chain to deny all traffic from 142.204.141.XXX (XXX is the PC beside you). Also log these denied packets with log level 'info'.
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| − | #Add a rule to the INPUT chain of the filter table that allows all new tcp ssh connections.
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| − | #Make a new chain named MYICMP in the filter table.
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| − | #Add a rule to your MYICMP chain that denies ICMP pings from 142.204.141.XXX (the PC beside you).
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| − | #Add a rule to your MYICMP chain that denies ICMP pings originating with MAC address of 11:22:33:44:55:66 (NOTE: to test this you'll have to change the MAC address of the PC beside you with the ifconfig command).
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| − | #Add a rule to your MYICMP chain that allows ICMP pings from anywhere.
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| − | #Add a rule to the INPUT chain of the filter table to send ICMP ping packets to your MYICMP chain.
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| − | #Change the default policy on the INPUT chain in the filter table to DROP.
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| − | ===Testing your custom firewall===
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| − | #Use nmap to scan your firewall from 142.204.141.XXX. If you don't have nmap on your system then install it.
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| − | #Use ping and ssh from 142.204.141.XXX (and elsewhere) to verify your firewall is working properly. Be sure to check the log file for your unsuccessful ssh attempts.
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| − | #Save your firewall rules.
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| − | == Completing the Lab ==
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| − | Answer the following questions
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| − | #What is your full name and Seneca student ID?
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| − | #Show your firewall rules using the output of the iptables-save command.
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| − | #Show the results of your nmap scans. Be sure to also show the exact nmap command you used.
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| − | #Show the log records generated by your invalid ssh attempts.
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| − | #What iptables rule would you need to add to your firewall to allow a maximum of 3 concurrent ssh connections from 142.204.141.XXX to your host?
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