Linux Linux Namespaces: Building Lightweight Containers

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Linux Namespaces: Building Lightweight Containers

Hello again, Hack Tools Dark Community!

Now that we've explored individual namespaces, it's time to combine them to create a lightweight container manually — without using Docker or other heavy tools!

• ⏺ Combine Multiple Namespaces for Full Isolation:
  We can isolate PID, NET, MNT, UTS, IPC, and USER all at once to simulate a full container environment.
  
  Example:
  
  

  sudo unshare --fork --pid --mount --uts --ipc --net --user --mount-proc /bin/bash

  
  Inside this new shell:
  1. You have your own process tree (PID namespace).
  2. You can set a different hostname (UTS namespace).
  3. You can create isolated mounts (MNT namespace).
  4. You have your own network stack (NET namespace).
  5. You have isolated IPC resources.
  6. You have separate user IDs (USER namespace).
• ⏺ Quick Setup Inside the Container:
  
  After launching the container shell, you can configure it:
  
  Set a new hostname:
  

  hostname mycontainer

  
  Create a private tmpfs mount:
  

  mount -t tmpfs tmpfs /tmp

  
  Bring up a loopback network:
  

  ip link set lo up

• ⏺ Bonus: Chroot for a Real Filesystem Jail:
  
  If you want an even stronger isolation layer, combine namespaces with chroot to provide a completely minimal filesystem:
  
  

  mkdir /tmp/container_root
  debootstrap --variant=minbase stable /tmp/container_root http://deb.debian.org/debian
  sudo chroot /tmp/container_root /bin/bash

  
  Now you have a minimal Debian environment inside your manual container!

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Disclaimer:
This post is for educational purposes only. Unauthorized use of containers or system isolation methods on production systems can cause unexpected behavior. Always test in controlled environments.

Dive into the conversation! Have you built your own manual containers? Share your methods, tricks, and ideas!