# Port Scanning ### Open Port Behaviour Syn -> Syn + Ack -> Ack *** ### Closed Port Behaviour Syn -> Rst + Ack *** ### Nmap Version Scan (-sV) Behaviour Syn -> SYN + Ack -> Ack -> Banner -> Rst + Ack *** ### Tcpwrapped Port Status It means that TCP Handshake was completed but remote host closed the connection without receiving any data. It could be an indicator for **FIREWALL**. *** ### Get Reason for Open or Closed Ports Use nmap `--reason` switch to show explanation. We may learn from it that remote host sent an `RST` packet during TCP Handshake which probably means firewall prevented the handshake. *** ### Masscan Useful for large networks to fastly map the network. `masscan -p22,80,443,445,53,8080 -Pn --rate=800 --banners 192.168.18.0/24 -e tap0 --router-ip 192.168.18.1 --echo > masscan.conf` * rate means 800 packets per second * banners used to fingerprint services * `-e` tells which network interface to use * `-echo` file generates a template to use for scan * Can be used with `-c` switch *** --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://notes.nomanaziz.me/cybersecurity/penetration-testing/elearnsecurity/ejpt/footprinting-and-scanning/port-scanning.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.