linuxexpert-practice-labs/labs/lpic-3-303/335-2-penetration-testing

LPIC-3 335.2: Penetration testing

Scan this VM from the peer with nmap: fingerprint it, check that a firewall change does what you expect, and run some NSE scripts. Only ever scan machines you own.

Before you start

Setup installed nginx and runs it on ports 80, 8080 and 8081, so there is something to find. The peer, at 10.99.0.2 (name peer), is the scanner; it sits on this VM's second network, where this VM is 10.99.0.1. Run commands there with sudo ip netns exec lepeer COMMAND. It shares this VM's files, so a scan it saves in /root/scans is here too.

The firewall, if it's running, is yours to open for ports 80, 8080 and 8081. Keep your scans in /root/scans. The nftables table only lasts until a reboot.

Tasks

1. Install nmap (and ndiff, on Ubuntu). From the peer, find the hosts on 10.99.0.0/24, then run a SYN scan of ports 22, 80, 443, 8080 and 8081 on 10.99.0.1, saved in all formats as /root/scans/before. Ports 22, 80, 8080 and 8081 must show open.
2. From the peer, probe the services and the operating system on ports 22, 80 and 8080, with the XML output in /root/scans/services.xml. Write the nginx version it found (just the number, like 1.2.3) to /root/lab-answers/2.
3. On this VM, install nftables if it's missing and add a table inet scanlab that drops port 8080 and rejects port 8081 with a TCP reset, for the peer only. Port 80 must still answer the peer.
4. From the peer, scan again as in task 1, saved as /root/scans/after. Then run an ACK scan of ports 22, 8080 and 8081, and write the port it reports as filtered to /root/lab-answers/4.
5. Compare the two scans with ndiff and save its output in /root/scans/diff.txt. (Ubuntu only: AlmaLinux has no ndiff.)
6. Run the ssh2-enum-algos script against port 22 and save the output in /root/scans/ssh-algos.txt. Count the NSE scripts in the vuln category and write the number to /root/lab-answers/6.

Hints

• nmap -sn 10.99.0.0/24; nmap -sS -p ... -oA before 10.99.0.1.
• -sV -O -oX FILE; nginx -v tells you the answer to check against.
• nft add table, add chain ... '{ type filter hook input priority 0; policy accept; }', add rule ... ip saddr 10.99.0.2 tcp dport 8080 drop, ... reject with tcp reset. From the peer: curl --max-time 3 http://10.99.0.1:8080/.
• -sA sorts ports into filtered and unfiltered.
• ndiff before.xml after.xml.
• --script NAME; /usr/share/nmap/scripts/script.db lists each script's categories.