The PortSentry program can be configured in six different modes of operation, but be aware that only one protocol mode type can be started at a time. To be more accurate, you can start one TCP mode and one UDP mode, so two TCP modes and one UDP modes, for example, doesn't work. The available modes are:
- portsentry -tcp
basic port-bound TCP mode
- portsentry -udp
basic port-bound UDP mode
- portsentry -stcp
Stealth TCP scan detection
- portsentry -atcp
Advanced TCP stealth scan detection
- portsentry -sudp
Stealth UDP scan detection
- portsentry -audp
Advanced Stealth UDP scan detection
In my case I prefer to start TCP in Advanced TCP stealth scan detection protocol mode and UDP in Stealth UDP scan detection protocol
mode. For information about the other protocol modes, please refer to the README.install and README.stealth file under the PortSentry source directory.
For TCP mode I choose:
- -atcp
Advanced TCP stealth scan detection mode
With the Advanced TCP stealth scan detection mode -atcp protocol mode type, PortSentry will first check to see what ports you have running on your server, then remove these ports from monitoring and will begin watching the remaining ports. This is very powerful and reacts exceedingly quickly for port scanners. It also uses very little CPU time.
For UDP mode I choose:
- -sudp
Stealth UDP scan detection mode
With the Stealth UDP scan detection mode -sudp protocol mode type, the UDP ports will be listed and then monitored.
To start PortSentry in the two modes selected above, use the commands:
[root@deep] /# /usr/psionic/portsentry/portsentry -atcp
[root@deep] /# /usr/psionic/portsentry/portsentry -sudp
You can add the above lines to your /etc/rc.d/rc.local script file and PortSentry software will be automatically started if you reboot your system.
These are the files Installed by Portsentry on your system:
/usr/psionic
|
/usr/psionic/portsentry
|
/usr/psionic/portsentry/portsentry.conf
|
/usr/psionic/portsentry/portsentry.ignore
|
/usr/psionic/portsentry/portsentry
|