Updating Debian Offline 2 of 2

Welcome to Part 2

If you’ve been following along, you’ve gotten all of your offline files ready for deployment. If you missed that section you can go there now. In the sections below, we’ll discuss: the offline deployment, suggestions for running your offline deployment, and finally some fascinating ideas and projects I tried which have interesting potential but, unfortunately, did not work for me in this instance.

Disclaimer

This guide strictly deals with upgrading your system. It will not cover dist-upgrade although that is certainly something you can try and test. This information is provided as-is and, therefore, I take no responsibility for incidents with your equipment. I am a huge proponent of testing. Please ensure you know what you are doing before you attempt this.

Tools you need

1. WinSCP (If you’re using Windows and, for this, it’s almost, almost worth using Windows just to use this awesome, free tool)
2. Two systems. One should be online and the other is, of course, the offline one. They both should be very close build-wise. NOTE: If you want to test this out, I recommend changing the /etc/resolv.conf file on one of the systems. Comment: Remove everything in there and save it. This ensures apt will break without using the correct options and your test is as clean as it’s going to get without introducing USB flash drives.
3. Putty, or if you’re on Linux, SSH
4. Internet connection with both systems on the same network if you’re testing. Otherwise, you’ll just need internet for the online portion.

Copying over the Needed Files to the Offline System

Are you ready to get this done?

We’ll use WinSCP and transfer our files over to the “offline” system in its /tmp/ folder assuming it’s on your network and the only edits you made were to the /etc/resolv.conf file for testing. Otherwise, if you cannot reach your offline system with a network connection, you’ll have to use a flash drive. Mounting a flash drive is out of scope for this post, but the rest of the commands are relevant to your endeavor.

Assuming you’ve connected to your remote system with WinSCP, it’s time to copy some files over. This is where WinSCP shines because it saves so much time. We’re going to specifically copy over the:

1. Archives folder
2. Lists folder
3. Any additional packages (if its a .deb just put it in the archives folder once you’ve noted the full package name including its .deb extension) or scripts you may need.

We’re going to place these folders/files into the /tmp/ directory. Once everything is in the directory, assuming you kept the file names, we can get the actual update process started.

🔥 Spark Note From the Forge 🔥

Be a boss. Tar your files or zip them to make the transfer faster. Why? Because an archive, tar, or zip presents as a single file. The network won’t speed up and slow down as it finishes a file and starts a new one. Instead, as an archive or zip shows up as a single file the network keeps the pedal to the floor the entire way through. Want more mileage? Go full bore and use “xz” compression.

Moving files to the correct directories and cleanup

I kept the file names the same, so starting the in the /tmp/ directory I will run the following:

## Time to make the money. Clean out the archives section first. Make room on the tiny system.
## Move in the new archives and lists and clean up.
cd /tmp/;
apt-get clean;
mv archives/* /var/cache/apt/archives;
rm -rf archives;
rm -rf /var/lib/apt/lists/*;
mv lists/* /var/lib/apt/lists/;
rm -rf lists;

Can this be written more elegantly? Yes. But my intent is to fully show what I’m doing. Do I need semicolons at the end of these? No, but I tend to like to chain my commands together for situations where I can only paste one line into the terminal as it doesn’t make sense to write a script if I’m going to be on and off the system quickly. Believe me, I have found in the world of embedded systems that that happens. Like with Road Side Units (RSU) where you may be doing the same thing with very little variation dozens of times. You may love vi (one of the oldest unix/linux text editors), but me, not so much.

If everything has completed properly then we start pulling the triggers on things.

Running the Offline Update and Upgrades – Finally!

sed -i 's/jessie/stretch/g' /etc/apt/sources.list;
apt-get update --no-download;
apt-get upgrade -yf --no-download --ignore-missing;

For the upgrade, you can try this instead to keep the default options, but I have not had much success with it:

DEBIAN_FRONTEND=noninteractive apt-get upgrade -yf --no-download --ignore-missing -o "Dpkg::Options::=--force-confdef" -o "Dpkg::Options::=--force-confold";

So what does all of this do? If you remember from the previous blog, the sed command changed over “jessie” to “stretch” in one line. You can change the words to be what you need. For instance, you could make it look like this:

sed -i 's/stretch/buster/g' /etc/apt/sources.list;

But for this case, whatever you used on the online system must be used for the offline system. Is it really necessary? For documentation purposes at a minimum, yes. It’s a cheap, short, lazy way to let folks know what the offline system has. Don’t be that guy that leaves other folks wondering.

The next line simply updates the package lists in the system. This is important as we want the package database to be updated with the latest packages for our distributions archives we just moved from /tmp/ to the archives folder.

Once we get to the upgrade line, you’re in the home stretch. The system should be able to begin checking the archive folder for the necessary packages and will begin the upgrade process. I found there was no automation on my side as sometimes I needed glibc to be upgraded, for instance, which brought up a blue screen (updating grub will also bring up a blue screen requesting input). With that in mind, I’d plan to stick around and see things through.

But wait! What about my other offline packages that are not part of the main repository? Like that influxdb package, you pulled down. What happens there? Does apt-get upgrade or apt-get install work for that?

Not in my experience. What I did was throw those packages in the archives folder and then used dpkg to install it like so:

pushd /var/cache/apt/archives;dpkg -i influxdb_1.7.9-1_amd64.deb;popd

This is, again, not the slickest way you can write this, but, hopefully, it gives you an idea for a one-liner install.

Things I Tried that Failed

My main, initial challenge was that I had no internet on the remote boxes I needed to reach. I had a vpn connection and ssh. So naturally I tried to do a reverse ssh proxy which failed for me. I tried using port forwarding with ssh as well, and again, it didn’t come through. Trying to provide internet to a remote box over vpn was making me bang my head!

Time for plan b, and that turned out to be a project called sshuttle. It’s a neat project written in python that performs as a sublevel vpn, dns tunnel and more. It didn’t work out for me, but it might work out for you. Here’s what the project creator had to say on their github:

“Transparent proxy server that works as a poor man’s VPN. Forwards over ssh. Doesn’t require admin. Works with Linux and MacOS. Supports DNS tunneling.”

https://github.com/sshuttle/sshuttle

🔥 Spark Note From the Forge 🔥

What a bummer! I couldn’t get this python project installed right away. I’m so accustomed to working with linux scripts that it didn’t cross my mind that you might need to run a python project with a python installer! This project does need a separate project called “setuptools“.

Inside of that project, you will need to run an initial setup script as well. Another “gotchya” is you will need to match the version of setuptools that the creator of sshuttle is using, but here is a link you can use to get an idea and get started (https://pypi.org/project/setuptools/).

Well how do I install this project offline then? You will need to get all the project files, and then do what you’ve done with the archive files and copy them to /tmp/. Change directory into that file. From there, you can run the following code to install it on the user account you are logged into the remote system with:

python install setup.py –user

Well, so much for sshuttle then. I also gave a project called apt-offline a try. This was promising, but in the end, it also didn’t fulfill my needs. It did, however, set me down the path to understanding the Debian system better. While this project simplifies things for the average user, it still didn’t do everything I wanted. You can check out that project here if you want to give it a try: (https://github.com/rickysarraf/apt-offline).

That wraps it up for this post. Hopefully, you found the droids you were looking for and this has been useful.