CLOSING OPEN FILES

With the spread of Hackers and Hacking incidents, the time has come, when not only system administrators of servers of big companies, but also people who connect to the Internet by dialing up into their ISP, have to worry about securing their system. It really does not make much difference whether you have a static IP or a dynamic one, if your system is connected to the Internet, then there is every chance of it being attacked.

This manual is aimed at discussing methods of system security analysis and will shed light on as to how to secure your standalone (also a system connected to a LAN) system.

Open Ports: A Threat to Security?

In the Netstat Tutorial we had discussed how the netstat -a command showed the list of open ports on your system. Well, anyhow, before I move on, I would like to quickly recap the important part. So here goes, straight from the netstat tutorial:

Now, the ‘–a’ option is used to display all open connections on the local machine. It also returns the remote system to which we are connected to, the port numbers of the remote system we are connected to (and the local machine) and also the type and state of connection we have with the remote system.

For Example,

C:\windows>netstat -a

Active Connections

Proto Local Address Foreign Address State

TCP ankit:1031 dwarf.box.sk:ftp ESTABLISHED

TCP ankit:1036 dwarf.box.sk:ftp-data TIME_WAIT

TCP ankit:1043 banners.egroups.com:80 FIN_WAIT_2

TCP ankit:1045 mail2.mtnl.net.in:pop3 TIME_WAIT

TCP ankit:1052 zztop.boxnetwork.net:80 ESTABLISHED

TCP ankit:1053 mail2.mtnl.net.in:pop3 TIME_WAIT

UDP ankit:1025 *:*

UDP ankit:nbdatagram *:*