1. Installation.
1.1. Install Using The 'apt-get' Software
sudo apt-get install apt-cacher
2. Monitoring & Troubleshooting
3. Stopping And Starting The apt-cacher Daemon.
This is really simple just run the dnsmasq startup script in /etc/init.d with stop, start or restart. That was simple
sudo /etc/init.d/dnsmasq stop
sudo /etc/init.d/dnsmasq start
sudo /etc/init.d/dnsmasq restart
4. Further Information.
4.1. Links I Found Useful
So, you have Ubuntu, you love Ubuntu, and you've spread the love throughout your home. Perhaps you have a few family members using it happily, or maybe you simply enjoy having a different computer in every room of the house.
Whatever the reason, you have multiple machines running this fine operating system. One problem, though: all those updates! You love getting upgraded software, but having to download it so many times really eats away at your bandwidth.
Luckily for you, you're using open source software. You're not alone in this concern, and a solution already exists.
This guide will get you setup with apt-cacher, a tool that caches Debian package files for your home network. When one of your machines requests a package, apt-cacher will check to see if it has it, and if it does, send it back to the client without downloading a single byte. If not, then it goes to the repository and grabs the package, streaming it back to the client as it does, and keeps it for future use.
Things to note: 1. A repository needn't be specified on the server machine for a client to access it. The server acts as a kind of proxy which keeps a copy for itself. 2. This is not Ubuntu-specific. Any Debian-based distro should be able to act as both a server and a client, although you may have to adapt some of the steps for yourself.
I've noticed that the new proxy setup runs significantly faster, at least for me, than the old one (close to direct download speeds). Let me know if you experience decreased performance using this howto.
Part Zero: The Formalities Each step of this guide has been tested on my own home network between a laptop and a desktop machine, each running Feisty 32-bit. Also tested with two desktops and a laptop on Gutsy, and most recently with two desktops (Hardy and Gutsy). No errors have yet occurred due to differing versions. Skip Da Shu confirms this as working on a network with multiple derivatives, architectures and releases.
Information for this guide was gathered primarily from the apt-cacher man page. I consulted this article (http://www.linuxjournal.com/article/1058) for help with inetd. It's rather dated, but quite useful.
Part One: The Server You'll need to select a server for this setup. It should have a fair bit of space to spare, particularly if the client machines belong to an eclectic group. For those with more advanced partitioning schemes, the cache is kept in /var/cache/apt-cacher by default, but this can be changed.
To get the ball rolling, we install the software in question:
sudo apt-get install apt-cacher
With it successfully installed, we have to tell it how to start. There are two options for this. You can have it run in daemon mode (always on), or you can get inetd, which is a program to launch server applications on request. The obvious advantage is that it saves you memory and CPU power, but it does take a bit more setup. If you're expecting a lot of traffic, go with the daemon mode. If you're a home user, chances are you'll want to go with inetd.
Daemon Mode This is really quite easy. First, we'll need to edit our services file:
sudo nano /etc/services
The following lines can go anywhere really, but the end of the file is convenient, particularly if you're planning to have many services running from this machine:
apt-cacher 3142/tcp
apt-cacher 3142/udp
3142 is the default port. I see no reason to change it, but if you have one, you may. If so, you'll need to change the daemon_port option in /etc/apt-cacher/apt-cacher.conf
One more file to edit:
sudo nano /etc/default/apt-cacher
Set AUTOSTART to 1 to get the daemon to launch at boot time.
To launch it now, simply type the following:
sudo /etc/init.d/apt-cacher start
Now, we're all done for the server side of things. Skip down to Part Two
Inetd Mode To kick things off, we'll need to install the service:
sudo apt-get install inetutils-inetd
Next, we edit a couple of files:
sudo nano /etc/services
Add these two lines to the end of the file:
apt-cacher 3142/tcp
apt-cacher 3142/udp
Now, we have to setup inetd:
sudo nano /etc/inetd.conf
Add this line:
apt-cacher stream tcp nowait www-data /usr/sbin/tcpd /usr/sbin/apt-cacher -i
Now, restart the inetd server:
sudo /etc/init.d/inetutils-inetd restart
You're done!
Part Two: The Client To use apt-cacher, your clients need to redirect their requests to the server machine. APT has its own proxy configuration. Thanks to omegamormegil for this tip Type the following in a terminal:
echo "Acquire::http::Proxy \"http://hostname:3142\";" | sudo tee /etc/apt/apt.conf.d/01proxy
Where hostname is a valid identifier for your server (for home users, an IP address will probably be convenient).
For laptop users, this means that you'll be unable to update using this method while on the road (unless you have a global route to your server, although the speed will be greatly reduced). To switch back to direct updates, type the following command:
echo "Acquire::http::Proxy \"http://\";" | sudo tee /etc/apt/apt.conf.d/01proxy
Then once you get home, the command given above will get you using shared updates again.
Now, update!
sudo apt-get update
If all goes well, you should download packages as usual. Try downloading some software, or getting some updates. It should work pretty much as before.
If you are upgrading, these steps will not work. This appears to be a bug in Update Manager.
To upgrade, you must edit the 01proxy file to use direct updates as described above. Now, run the following command:
sudo sed --in-place s_http://_http://hostname:3142/_ /etc/apt/sources.list
The syntax may seem a little daunting, but this simply replaces any occurance of http:// with http://hostname:3142/. Once again, hostname must be a valid identifier for your server.
Upgrades should now work normally through the Update Manager. Once you've finished the upgrade, run the following command:
sudo sed --in-place s_http://hostname:3142/_http://_ /etc/apt/sources.list
Now edit the 01proxy file to set yourself to shared updates as described above.
So far, this is the only workaround I know of. I apologise to anyone who may have suffered this bug. Once more, thank you mssever for bringing this to my attention and providing a fix.
Part Three: The Transition Chances are your server's up to date,and has a fair package cache of its own. Why duplicate all of this fine work? apt-cacher comes with a migration helper for precaching. Type the following in a terminal to copy your cache over:
sudo mv /var/cache/apt/archives/*.deb /var/cache/apt-cacher/import
sudo /usr/share/apt-cacher/apt-cacher-import.pl
At the moment, the server machine itself will go downloading its own packages, rather than reusing those in the cache. To fix this, use the same proxy setup as used above on the clients, using "localhost" as the hostname.
The final step is optional, but it will help you free up space. The server is currently maintaining two caches: the regular apt one, and the shared cache.
If your server uses Synaptic at all, there's an option under Settings -> Preferences -> Files to delete packages after installation. Thanks to Skip Da Shu for pointing this out to me.
Unfortunately, I've not found a more universal solution to this yet. If your server does not use Synaptic, the following command will clear the regular cache:
sudo apt-get clean
To save us the pain of running this every day, we'll use anacron. Anacron is a scheduling program that executes a command every time it hasn't been executed for more than n days. It solves the flaw in cron of a computer that i sn't always on, and is really just nicer to use if your job doesn't need to be done at a specific time.
sudo nano /etc/anacrontab
Add the following line:
1 20 apt-clean apt-get clean
Part Four: The Removal To undo the changes made in this guide, you must remove the proxy configuration lines. You must also remove the line to clear the cache from /etc/anacrontab, or set the option in Synaptic back to its original value.
Purging inetutils-inetd, inetutils-tcpd, and apt-cacher will undo most of the remaining changes. Remove the two lines from the end of /etc/services, and your system should be back to the way it was.
Problems with apt-get try this. sudo dpkg --remove --force-remove-reinstreq clamav-daemon