\documentclass{standalone}
\usepackage{tikz}
\begin{document}
\begin{tikzpicture}
  % \node (server) at (0,0) {server};
  \node (wg0)      at (0,0) {wg0};
  \node (vio0)     at (0, 1) {vio0};
  \node (pf)       at (2, 1) {pf};
  \node (client)   at (-2, 1) {client};
  \node (internet) at (3, 3) {internet};
  \node (program)  at (4, 0) {program};
  \draw[->,blue] (client) -- (vio0);
  \draw[->] (vio0) -- (pf);
  \draw[->,orange] (pf) -- (wg0);
  \draw[->,orange] (wg0) -- (vio0);
  \draw[->,blue] (vio0) -- (internet);
  \draw[->,orange] (program) -- (wg0);
\end{tikzpicture}
\end{document}
%%% Local Variables:
%%% mode: latex
%%% TeX-master: t
%%% End: