{A web-based \TeX{} previewer: Ecstasy and agony} {Michael Doob} {The appeal of a web-based combined \TeX{} editor and previewer is instantaneous. It allows not only the easy testing of snippets of code, the writing of short abstracts and even of short papers, but also allows sharing of the results over the web. Unfortunately, even a benign program like \TeX{} presents serious security risks, and care must be used when exposing such an application. This presentation includes a web-based viewer of the type just described. It will be used to: %\begin{itemize} \item\bull Illustrate how remarkably easy it is, using tools readily available, to construct a previewer, \item\bull give examples of potential security problems,~\rlap{and} \item\bull indicate some solutions to these problems. %\end{itemize} The context of this talk is a \acro{LAMP} (Linux, Apache, My\SQL, \PHP) environment, but the basic ideas can be applied to any of the common operating systems. }