• Port Scanner built with Nim

This is a quick & dirty port scanner I "whipped up" to learn more about the Nim programming language. It's pretty junk, but hey, I'm learning here. :)

• Install Nim
  • https://nim-lang.org/install.html
• Clone the repo
  • git clone https://github.com/daniellowrie/NimScan.git
• Build nimscan
  • nim c -d:release nimscan.nim
    • To Cross-Compile For Windows from Linux:
      • You'll need MinGW installed on your Linux system
        • https://nim-lang.org/docs/nimc.html#crossminuscompilation-for-windows

Usage

• Use is pretty straight forward, and has 2 modes of operation...

  1. Command-Line Mode
  2. Interactive Mode

• Command-Line Mode

  • You pass all the parameters to nimscan
    • ./nimscan targetIP/hostname START_port END_port
    • ./nimscan 192.168.1.81 20 1024
    • ./nimscan scanme.nmap.org 20 1024

• *Interactive Mode

  • You just run nimscan without any arguments and you'll be asked for the necessary elements

    • ./nimscan
      TargetIP: 192.168.1.81
      START Port: 20
      END Port: 1024
      
      Nim Port Scanner
      ================
      Port Open: 22
      Port Open: 80
      

      • You can use a hostname or IP address for 'TargetIP'

• I can only can 1023 ports at a time.

  • The socket connection opens File Descriptors
    • I'm not yet sure how to close them.
      • the std/net proc close() doesn't seem to do it
    • Generates Error: unhandled exception: Too many open files [OSError]
      • That said, I've been able to scan 1000 ports against Internet-facing hosts in about 2 min

• Windows Defender thinks that Nim is Malware

  • If you install Nim on Windows, there is a decent chance that Defender will flag it as malware
    • This is due to the fact that Nim has been used in the recent past to create malware
      • AV vendors went the easy route of just dropping the hammer on Nim it seems
        • Even your cross-compiled EXEs will get busted
          • Sometimes a quick reinstall of Nim fixes this

• Command-Line Mode is ALL or NOTHING!

  • Nim causes errors if you don't use the expected amount of arguments
    • Therefore you can use NO command-line args (aka Interactive Mode)
    • Or you must supply ALL the expected args, lest ye suffer a fatal error! ARRGGHH!!!