Limax PC Services
Security Considerations
How secure is your computer? Are you confident that no-one can read, alter or delete your files when you are connected to the Internet? Poorly configured software makes many systems insecure. Potential intruders use scanner programs to look for poorly protected systems. They may be looking for access to files, which could include personal information such as credit card numbers. They may be looking for access to services such as mail relays or proxy servers. Or they may be looking for certain forms of virus which provide them with backdoor control of your system.
Open mail relays
An open mail relay will accept any email addressed to a third party, and pass it on to that third party. In the early days of the Internet this was considered a useful and necessary service but nowadays it is just irresponsible. Junk emailers are always on the lookout for open relays to pass on their junk for them. It allows them to offload processing, cover their tracks and deflect complaints. Many people run open mail relays due to badly configured software. If you are one of them you are wasting your system resources and contributing to the junk email problem. You also risk having your domain blacklisted and being cut off by your ISP.
Open proxy servers
A proxy server is used to service Internet traffic, typically for a local area network (LAN). A poorly configured proxy server may accept connections from anyone and this is another vulnerability exploited by junk emailers. As with open mail relays, running an open proxy server will waste your system resources and could get you blacklisted or cut off by your ISP.
Firewalls
If you have a permanent Internet connection or spend long periods online, or you run a network, you should consider running a firewall. A properly configured firewall will control exactly what comes in and what goes out of your computer (whereas a badly configured firewall may stop you accessing the Internet altogether).
Unwanted inbound traffic could include scanner programs checking if they can access your files, looking for open mail relays or looking for trojans. Unwanted outbound traffic could include programs "phoning home", which may be reporting on your browsing habits or passing on other personal details. These programs may be "spyware", often installed along with other programs without your knowledge, or they may be trojans which have already infected your system and are now informing someone that they can control your machine remotely.
A proper firewall runs on a separate machine or may be combined with a router. For personal use a firewall program which runs on your own computer, and more correctly called a packet filter, should suffice. Some firewalls only monitor inbound traffic and are not recommended. A firewall should never be considered as a substitute for an anti-virus program, or as justification for running a poorly configured system.
