\begin{tikzpicture}
    \tikzstyle{point}=[circle,thick,draw=black,fill=black,inner sep=0pt,minimum width=4pt,minimum height=4pt]

    \foreach \x in {0,1,2}
    \foreach \y in {0,1,2}{
      \node (a)[point] at (\y,0) {};
      \node (b)[point] at (\x,1) {};
        \draw (a) -- (b);
    }
\end{tikzpicture}