Script smb-flood

Script types: hostrule
Categories: intrusive, dos

Script Summary

Exhausts a remote SMB server's connection limit by by opening as many connections as we can. Most implementations of SMB have a hard global limit of 11 connections for user accounts and 10 connections for anonymous. Once that limit is reached, further connections are denied. This script exploits that limit by taking up all the connections and holding them.

This works better with a valid user account, because Windows reserves one slot for valid users. So, no matter how many anonymous connections are taking up spaces, a single valid user can still log in.

This is *not* recommended as a general purpose script, because a) it is designed to harm the server and has no useful output, and b) it never ends (until timeout).

Script Arguments


The amount of time the script should run. Default: 30m

randomseed, smbbasic, smbport, smbsign

See the documentation for the smb library.

smbdomain, smbhash, smbnoguest, smbpassword, smbtype, smbusername

See the documentation for the smbauth library.

Example Usage

nmap --script smb-flood.nse -p445 <host>
sudo nmap -sU -sS --script smb-flood.nse -p U:137,T:139 <host>

Script Output

Target down 30 times in 1m.
320 connections made, 11 max concurrent connections.
10 connections on average required to deny service.



  • Ron Bowes

License: Same as Nmap--See