CoLTE

CoLTE is the Community LTE Project. It is designed to be an all-in-one turnkey solution that sets up a small-scale locally-run cellular network. CoLTE consists of several main elements working together:

1. An all-in-one software EPC, powered by open5gs.
2. Network monitoring software, powered by haulage, to keep track of how many bytes each user uses and bill appropriately.
3. A Web GUI that lets network users check the status of their account, top up, transfer/resell credit, and buy data packages.
4. A Web-based admin tool that lets administrators manage all the information above.
5. Local Web and DNS serving/caching via Nginx and BIND.
6. CLI utilities for managing configuration and user accounts.

Installation

Here is a tutorial for novice users that attempts a step-by-step walkthrough of a full CoLTE EPC installation, produced in collaboration with the Seattle Community Network.

Basic System Requirements:

We now support Ubuntu 18.04 (bionic), Ubuntu 20.04 (focal), and Debian 10 (buster). Our primary deployments are currently on buster and focal, and we have better test coverage for those distributions. We recommend buster for new installs.

Which Components Do I Need?

The CoLTE project is made up of several components, which may not all be necessary for all deployments. We currently build the following high-level packages supporting different accounting/billing methodologies and different core networks.

• colte-cn-4g - Provides a cellular "network in the box" (NITB) and associated configuration scripts for managing the network.

• colte-prepaid - Provides a prepaid accounting and billing suite integrated against a local colte core network.

• colte (deprecated) - For backwards compaitibility with existing installs, this package installs both colte-prepaid and colte-cn-4g. Installing this package is the same as installing both the colte-cn-4g and colte-prepaid components separately. We recommend new users install their specifically needed components rather than using this meta-package.

• colte-essential (transitive) - Provides basic shared capabilities across colte packages. This should be installed automatically as a dependency via apt if any of the other component packages are installed.

Apt Packages

To ease deployment, we host pre-compiled apt packages on our server for x86_64 and arm64 for all supported distributions. You will need to add our apt repository to get colte and haulage, and you will also need to add the open5gs repository separately. To do this, use the following commands according to your distribution:

Debian 10 (buster) (Recommended)

echo "deb [signed-by=/usr/share/keyrings/colte-archive-keyring.gpg] http://colte.cs.washington.edu $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/colte.list
sudo wget -O /usr/share/keyrings/colte-archive-keyring.gpg http://colte.cs.washington.edu/colte-archive-keyring.gpg
wget -qO - https://www.mongodb.org/static/pgp/server-4.2.asc | sudo apt-key add -
echo "deb http://repo.mongodb.org/apt/debian buster/mongodb-org/4.2 main" | sudo tee /etc/apt/sources.list.d/mongodb-org.list
wget -qO - https://download.opensuse.org/repositories/home:/acetcom:/open5gs:/latest/Debian_10/Release.key | sudo apt-key add -
sudo sh -c "echo 'deb http://download.opensuse.org/repositories/home:/acetcom:/open5gs:/latest/Debian_10/ ./' > /etc/apt/sources.list.d/open5gs.list"
sudo apt update
sudo apt install colte-cn-4g colte-prepaid

Ubuntu 18.04 or 20.04 (bionic or focal)

echo "deb [signed-by=/usr/share/keyrings/colte-archive-keyring.gpg] http://colte.cs.washington.edu $(lsb_release -sc) main" | sudo tee /etc/apt/sources.list.d/colte.list
sudo wget -O /usr/share/keyrings/colte-archive-keyring.gpg http://colte.cs.washington.edu/colte-archive-keyring.gpg
sudo apt install software-properties-common
sudo add-apt-repository ppa:open5gs/latest
sudo apt update
sudo apt install colte-cn-4g colte-prepaid

After installation, the admin tool will be running and listening on http://localhost:7998, and the user webgui will be running and listening on http://localhost:7999. You can start or stop these services with systemctl {start | stop} {colte-webgui | colte-webadmin}, respectively.

Haulage can be started with sudo haulage or sudo systemctl start haulage, but will likely fail if not first configured for your system (see configuration). To start Open5Gs, refer to the docs here.

Working With The Source:

The top-level Makefile will compile all source and generate .deb packages if you type make. If you want to run the webgui or webadmin from source in a local terminal without doing a system-wide installation, cd into the corresponding directory and then do the following:

npm install
npm start

Configuration

After installation, pointers to all the various config files can be found in /etc/colte/. The main config file is config.yml. After you edit this file, run colteconf to reconfigure all components and restart them as necessary. Note that you must run colteconf at least once after installing CoLTE, because there is no way for us to know some of the options (e.g. upstream and downstream interfaces).

Note: In the current state of this repo, running colteconf will give you a python type error. We are working on a fix, but for now, delete the spaces and hyphens in /etc/open5gs/mme.yaml so the gummei and tai sections look as they do below:

  gummei:
    plmn_id:
      mcc: XXX
      mnc: YY
    mme_gid: 2
    mme_code: 1
  tai:
    plmn_id:
      mcc: XXX
      mnc: YY
    tac: 1

Basic Configs:

Conceptually, your machine will need two network connections: one to the Internet (the upstream WAN) and another to the eNodeB (the downstream LAN) - these can actually be the same interface, it doesn't matter.

Set wan_iface to your upstream (Internet) interface, and enb_iface_addr to the downstream interface's address/subnet. Don't worry about matching lte_subnet to any value in particular, because this subnet is created and assigned to the virtual ogstun interface used by the Open5Gs pgw.

Adding Users

Once you’ve configured the system, you will have to add user accounts. The best way to do this is to use coltedb. You will have to provide the user’s IMSI, phone number (can be any value you choose), static IP address, and security values (KI and OPC).

Configuring The Phone

Once you’ve added a user, you may have to configure the phone’s APN settings as well. This is easy to do: go to Settings -> Mobile Network -> Advanced -> APN Settings and add an APN. The values for name and apn should both just be “internet”, you can leave everything else alone as it is.

Money And Accounting

This section requires your deployment have an accouting system installed (like colte-prepaid). See Which Components Do I Need? for more information.

System Architecture

Setting the metered variable to true (this is on by default) turns on three services: haulage, colte-webgui, and colte-webadmin. haulage monitors the ogstun interface, draws user accounts down from a quota, and turns them off when they hit zero. Users can interact with their account (transfer money, buy data packages, etc) via the webgui - accessible by default at http://(your IP address):7999. Similarly, we provide a separate web-based tool for network administrators to change account balances, enable or disable specific users, topup accounts, and transfer money from one user to another. It is accessible only from the EPC, at http://(your IP address):7998. The username is admin and the default password is password.

Administration

To add money to a user’s account, use coltedb topup or the webadmin tool. By default, users start out with a zero money balance and 10MB of data-balance. To configure the data packages users can buy, as well as their price-points, edit /etc/colte/pricing.json.

WebAdmin and WebGUI

Both of these services are started automatically after installation. They have detailed configurations in /etc/colte/{webgui.env|webadmin.env}; for more details, consult /{webadmin|webgui}/README. You will have to restart these services after you change any of these variables, and you can do so with:

sudo systemctl {start|stop} {colte-webadmin|colte-webgui}

Log Files

/var/log/colte.

Known Issues

• Right now, the webservices are only hosted as high-number ports. In the interest of not dominating your system we do not currently integrate with any apps that serve DNS or HTTP (e.g. bind or nginx); we plan to eventually support this. In the meantime, you are responsible for either (a) changing the app to listen on 80 or (b) plumbing a port-forwarding solution using nginx or something similar.
• open5gs-pgwd conflicts with systemd-networkd: The open5gs package has a known issue wherein open5gs-pgwd conflicts with systemd-networkd. This is already fixed in source, and will be fixed in the packages as soon as Sukchan drafts a new release of open5gs. Until then, you will see an error after running colteconf, but the following commands will fix it:

sudo systemctl stop open5gs-pgwd
sudo systemctl restart systemd-networkd
sudo systemctl start open5gs-pgwd

• systemd-networkd sometimes does not bring up the tun IP address: I have seen this issue occasionally, but have not been able to reproduce it consistently. I am not entirely sure what causes it, but have found some other discussion about a similar issue. The issue is claimed to have been fixed in systemd-241, but Ubuntu 18.04 ships with version 237. This issue pops up occasionally, but usually right after you change the lte_subnet variable and run colteconf. Sometimes, but not always, starting (or restarting) open5gs-pgwd and/or systemd-networkd will fix this issue. If not, a system reboot usually does the trick.

What about OAI?

Prior to Fall 2019 we maintained a stable branch of the Open Air Interface 4G-LTE packet core. We encountered numerous issues attempting to maintain this fork, including difficulty upstreaming stability fixes and continuous large churn in the upstream codebase. In Fall 2019 we migrated to [open5gs](https://github.com/open5gs/open5gs , which has a more responsive development team and (in our opinion) better code hygene. We now only support open5gs, and no longer provide maintenance support for OAI-based installs. We encourage OAI LTE users to check out open5gs and join the open5gs community!