nmap in Cygwin: seamlessly

  1. Download & install nmap “self-installer” .exe and install Npcap when asked by the Nmap installer.
  2. in Cygwin add to ~/.bash_profile

    alias nmap="/cygdrive/c/Program\ Files\ \(x86\)/Nmap/nmap.exe"
    

    Note the \ and \( are vital for Cygwin shell to interpret the command correctly

  3. Open a new Cygwin window to start using nmap

Test

nmap 8.8.8.8

results in

Starting Nmap ( https://nmap.org ) 
Nmap scan report for google-public-dns-a.google.com (8.8.8.8)
Host is up (0.0092s latency).
Not shown: 998 filtered ports
PORT STATE SERVICE
53/tcp open domain
443/tcp open https

Nmap done: 1 IP address (1 host up) scanned in 7.41 seconds

Troubleshooting

  • errors about interface → try running Cygwin as Administrator (right click on Cygwin icon).
  • find interface names available to nmap
    nmap --iflist
    

Notes

  • to find servers with a particular port open on a subnet, try this Python code that scans for servers without nmap.
  • If you don’t install Npcap when asked in the nmap installer, nmap does not work. Nmap claimed no host existed at a known working IP address.

Why isn’t nmap built into Cygwin?

I think it’s because nmap requires deeper access to the Windows networking stack that would go beyond the normal scope of Cygwin as a guess. I have no particular technical familiarity with Cygwin networking at this level, but note that Nmap itself needs the separate program Npcap (forked from WinPcap) to do it’s job on Windows, particularly Windows 10.

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