[jupyterhub] add ssh

jupyterhub/base/Dockerfile

@@ -84,6 +84,11 @@ RUN mkdir -p /usr/local/venv && \
         && \
     ipython kernel install --name=default
 
+RUN apt-get update && \
+    apt-get install -y \
+        ssh && \
+    apt-get clean
+
 RUN chmod -x /etc/update-motd.d/*
 
 WORKDIR "${HOME}"