Tuesday, 29 July 2008

Netcat

What can you do with a simple programme that is designed to redirect traffic/Standard Out/ etc...

Well there is the obvious, moving files. There are a number of less obvious uses as well. Some of these include:

  1. Port and Protocol Scanning
  2. Vulnerability Scanning
  3. Testing and making connections to open ports
  4. Acting as a virtual server or honeypot
  5. A simple port-scan logger
  6. A replay attack engine
  7. A backdoor into a system and a remote shell
  8. A forwarder and Relay

I shall be covering some of these uses of this one simple command over the next few days.

For the GNU Netcat Project site - see http://netcat.sourceforge.net/

The command options are:

  • -d detach from console, stealth mode
  • -e prog inbound program to exec
  • -g source-routing hop point[s], up to 8 addresses
  • -G num source-routing pointer. The options are 4, 8, 12, etc...
  • -iN for "N" seconds delay interval for lines sent, ports scanned
  • -l listen mode, for inbound connects
  • -L listen harder, re-listen on socket close
  • -n numeric-only IP addresses, no DNS names - no resolving
  • -o file hex dump of traffic
  • -p port local port number
  • -r randomize local and remote ports
  • -s address local source address
  • -t answer TELNET negotiation
  • -u UDP mode
  • -v verbose mode
  • -vv be more verbose
  • -wN for N secs timeout for connects and final net reads
  • -z zero-I/O mode [used for port scanning]

2 comments:

Anonymous said...

Do you have a working link for the windows version?

Craig S Wright said...

The link works- it has a compiled version and also has the source (nc.exe).

http://joncraton.org/files/nc111nt.zip

On top of this, there is a version for WindowsCE:
http://prt.fernuni-hagen.de/~bischoff/wince/Andreas_WINCE_stuff.html#netcat