port scanning

http://blog.miniasp.com/post/2008/07/A-magic-command-netcat.aspx

nc (netcat)

$ nc -z host.example.com 20-30


Server & Client

Server:
# tar -zcf - /etc | netcat -w 30 10.0.0.99 3456

Client:
# netcat -l -p 3456 > /backup/my_etc_backup.tar.gz

[Note] or use nmap