build: actually added firewalls to test container

One of the more interesting selling points about this project is that it
works through local system firewalls on Linux (iptables, nf_tables)

This commit makes the testing environments in the docker containers
actually have to go up against a firewall, one which has a default
incoming and outgoing policy of drop

docker-compose.yml

@@ -1,10 +1,13 @@
 version: '3.8'
 services:
   examples_bindshell_target:
-    image: ubuntu:20.04
+    build:
+      context: examples/secure-image
+      dockerfile: Dockerfile
     volumes:
       - ./target:/backdoor
     command: /backdoor/release/ex-bind-shell-backdoor
+    privileged: true
     
   examples_bindshell_client:
     image: alpine

examples/secure-image/Dockerfile

@@ -0,0 +1,22 @@
+# Copyright (C) 2023 Andrew Rioux
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# 
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+FROM ubuntu:20.04
+
+COPY ./setup.sh /container-init.sh
+
+RUN apt update && apt install -y iptables && chmod +x /container-init.sh
+
+ENTRYPOINT ["/container-init.sh"]

examples/secure-image/setup.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+# Copyright (C) 2023 Andrew Rioux
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as
+# published by the Free Software Foundation, either version 3 of the
+# License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# 
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+iptables -P INPUT DROP
+iptables -P OUTPUT DROP
+
+exec "$@"