hosts that already have cron available. This is useful when required functionality is only available via the web server. The cron daemon is the scheduling provider and periodically contacts the script using another tool such as Wget. In the case of a remote access capable webcron solution, cron can run the client component to execute the script. Security Concerns Since webcron solutions involve availability via a URL, there are several different security concerns that users should address. A webcron solution introduces issues of trust, opportunities for denial-of-service attacks, network or packet sniffing, executing a replay attack, and possible exposure of information. A webcron solution is an ideal entry point for criminal computer hackers. When using a third-party scheduling provider, users trust the third-party to not misuse the URL in any way. Users also have to assume that the connection between the third-party server and the web server is secure from hackers. When using a visitor based scheduling provider, users may inadvertently provide a possible venue for denial-of-service attacks. Also, if a script is written improperly, the script may unintentionally expose information about the server. When using a remote access scheduling provider, users usually have refined control over how communication takes place with the web server. If HTTP is used, the URL is sent in the clear over the wire but the data in the request is typically encrypted. This opens up the possibility of denial-of-service attacks and replay attacks. References Job scheduling