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Design a Container to Run a Proxy

For this lab, the aim is to design a container to run a proxy. We need to connect to the server, create our configuration there, and test it out from a client. We recommended opening two terminals for this lab, one for connecting to the server and one to the client. The client is a playground instance of our choice. Once that is set, we need to create a container with a CentOS 7 image on the server. Within the container, we must install and configure the open ssh server so that it cannot allow `root` login and allows only key-based authentication. After that, we must change it to run on the nonstandard port 61613. After that, we need to copy the public key generated on the client over to the container on the server. Next, we have to create a proxy tunnel from the client and run tests to see if the tunnel works properly. For testing this, we need Proxychains 4.

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Path Info

Level
Clock icon Intermediate
Duration
Clock icon 1h 30m
Published
Clock icon May 15, 2020

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Table of Contents

  1. Challenge

    Create a Container from a CentOS 7 image and Access It

    lxc launch images:centos/7/amd64 SOCKS5-Proxy

    lxc exec SOCKS5-Proxy bash

  2. Challenge

    Configure SSH to not Allow root Login and Only Allow Key-Based Authentication

    adduser tunnel -m
passwd tunnel

    yum install openssh-server vim

    vim /etc/ssh/sshd_config

    PermitRootLogin no
PubkeyAuthentication yes
ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM yes

    ESC
:wq
ENTER

    su tunnel

    mkdir /home/tunnel/.ssh
touch /home/tunnel/.ssh/authorized_keys

    chmod 700 /home/tunnel/.ssh
chmod 600 /home/tunnel/.ssh/authorized_keys

  3. Challenge

    On the Client, Generate a Key Pair and Copy the Public Key to /home/tunnel/.ssh/authorized_keys

    Set the path to /home/cloud_user/.ssh/SOCKS5.

    ssh-keygen

    cat /home/cloud_user/.ssh/SOCKS5.pub

    Copy the client public key to the server into authorized_keys

    /home/tunnel/.ssh/authorized_keys

  4. Challenge

    Configure SSH for Port 61613 and Expose the Container to the Outside World

    If under a different user in the container, just exit to root.

    exit

    vim /etc/ssh/sshd_config

    Port 61613

    ESC
:wq
ENTER

    systemctl restart sshd 

    exit

    Create a redirect on the host server.

    lxc list

    lxc config device add SOCKS5-Proxy myport443 proxy listen=tcp:0.0.0.0:443 connect=tcp:Container_IP:61613

  5. Challenge

    Run Tests to Confirm the Proxy Works on the Client (Refer to Lab Instructions for proxychains)

    ssh tunnel@SERVER_IP -i /home/cloud_user/.ssh/SOCKS5 -p 443

    exit

    ssh -D 65535 -q -C -N -f tunnel@SERVER_IP  -i /home/cloud_user/.ssh/SOCKS5 -p 443

    sudo apt install proxychains4 

    vim /etc/proxychains.conf

    Change the last line to:

    socks5  127.0.0.1 65535

    curl 'https://api.ipify.org?format=json'

    proxychains4 curl 'https://api.ipify.org?format=json'
A Cloud Guru - Labs - Design a Container to Run a Proxy
Author
A Cloud Guru

The Cloud Content team comprises subject matter experts hyper focused on services offered by the leading cloud vendors (AWS, GCP, and Azure), as well as cloud-related technologies such as Linux and DevOps. The team is thrilled to share their knowledge to help you build modern tech solutions from the ground up, secure and optimize your environments, and so much more!

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