optimizing installs and adding archive

docker/Dockerfile

@@ -1,17 +1,19 @@
 FROM python:3.6-stretch
 # Set the root password in the container so we can use it
 RUN echo "root:Docker!" | chpasswd
-RUN apt-get -y update
-RUN apt-get -y install libnetfilter-queue-dev iptables tcpdump netcat net-tools git graphviz openssh-server
+
+ENV PATH="/usr/sbin:${PATH}"
+RUN echo "deb http://archive.debian.org/debian stretch main contrib non-free" > /etc/apt/sources.list
+RUN apt-get -y update && \
+    apt-get -y install libnetfilter-queue-dev iptables tcpdump netcat net-tools git graphviz openssh-server && \
+    pip install netfilterqueue requests dnspython anytree graphviz netifaces paramiko tld docker scapy==2.4.3 psutil && \
+    DEBIAN_FRONTEND=noninteractive apt-get -y install tshark
+
 # Enable root SSH login for client testing
 RUN sed -i 's/PermitRootLogin without-password/PermitRootLogin yes/' /etc/ssh/sshd_config
 RUN sed -i 's/PermitRootLogin prohibit-password/PermitRootLogin yes/' /etc/ssh/sshd_config
 RUN sed -i 's/#PermitRootLogin yes/PermitRootLogin yes/' /etc/ssh/sshd_config
 
 # SSH login fix. Otherwise user is kicked off after login
 RUN sed 's@session\s*required\s*pam_loginuid.so@session optional pam_loginuid.so@g' -i /etc/pam.d/sshd
-
-RUN DEBIAN_FRONTEND=noninteractive apt-get -y install tshark
-ENV PATH="/usr/sbin:${PATH}"
-RUN pip install netfilterqueue requests dnspython anytree graphviz netifaces paramiko tld docker scapy==2.4.3 psutil
 ENTRYPOINT ["/bin/bash"]