Setting Up An ISP On ALT JeOS: A Step-by-Step Guide
Hey guys! So, you're looking to set up an Internet Service Provider (ISP) using ALT JeOS? That's awesome! This guide will walk you through, step-by-step, how to configure your system. We'll cover everything from the basic setup to network configurations, ensuring your ISP is up and running smoothly. Let's dive in and get started!
Understanding the Basics: What You'll Need
Before we jump into the technical stuff, let's make sure we're on the same page. To follow this guide, you'll need a few things. First, you'll need a server with ALT JeOS installed. Then, you'll need the script provided in the prompt. Make sure you have root access to your server. This script is designed to automate the process, making it easier for you to get your ISP up and running. Finally, some basic understanding of networking concepts like IP addresses, subnets, and routing will be super helpful. Don't worry if you're not a pro; we'll cover the essentials as we go along, but knowing the basics will make things smoother. Remember, patience is key, and we're here to help you every step of the way!
Environment Checks and Prerequisites
First things first, we need to ensure our environment is ready to roll. The script begins with a series of environment checks to make sure we have all the necessary tools. This includes checking for utilities like ip, sysctl, etc. The script uses the need function to check if these commands are available. If any required tool is missing, the script will let you know and exit, preventing any unexpected errors later on. Also, the script sets the timezone to Asia/Novosibirsk. Make sure to adjust this to your desired timezone. This is important to ensure that timestamps and logs are accurate, which helps in troubleshooting and monitoring your ISP. Finally, the script will use set -euo pipefail. This command will treat any error in the shell script as a failure, so you will be immediately notified about potential issues. This prevents errors from going unnoticed. Pretty cool, right?
Gathering Information: Configuration Parameters
Now, let's get down to the fun part - setting up the configurations! The script prompts you for the necessary parameters, such as the hostname, interface names, network settings, and NAT configuration. This is where you tailor the setup to your specific needs. The script is pretty flexible, allowing you to customize various settings. It starts by asking for the device's hostname, which defaults to isp-alt. Then, it asks for the interface names: WAN, HQ, and BR. WAN is for the internet connection, HQ is for the connection to the HQ-RTR (Headquarters Router), and BR is for the connection to the BR-RTR (Branch Router). Next, you'll be prompted for the HQ and BR subnets, along with their respective IP addresses and CIDR notations. These are the networks that your ISP will manage. Make sure to use the correct network settings provided by your ISP. Finally, the script prompts for a fixed external IP address for SNAT (Source Network Address Translation). If you specify an IP, the script will use SNAT; otherwise, it will use MASQUERADE. After entering all the necessary information, the script will display a summary of your configuration. Double-check everything before proceeding, as any incorrect information can cause problems down the road.
Setting up Hostname and Timezone
With the parameters collected, let's get the ball rolling! First, the script sets the hostname and timezone. Setting the hostname is crucial to identify your server on the network. The script uses the hostnamectl set-hostname command. Following this, it sets the timezone using the timedatectl set-timezone command. Proper time settings are essential for logging and diagnostics, helping you track events and troubleshoot issues. If timedatectl is not available, it uses a fallback method, linking the timezone file to /etc/localtime. It's a simple process, but it's essential for getting your ISP up and running.
Enabling IPv4 Forwarding
Next, the script enables IPv4 forwarding. IPv4 forwarding is the process that allows your server to forward network traffic between different interfaces. The script enables IPv4 forwarding using the sysctl command, which modifies the system's kernel parameters. It then creates a configuration file in /etc/sysctl.d to make this setting permanent across reboots. This is essential for routing traffic between your WAN, HQ, and BR interfaces. Without IPv4 forwarding, your server won't be able to act as a router, and your ISP won't function correctly. So, make sure you do it right.
Configuring Interfaces and Addresses
Now, let's configure the network interfaces. The script first brings up the HQ and BR interfaces using the ip link set command and then flushes any existing IP addresses. After that, it adds the IP addresses and netmasks to the HQ and BR interfaces. The script then brings up the WAN interface. For the WAN interface, the script checks if NetworkManager is installed. If it is, it uses nmcli to configure the interface with DHCP. Otherwise, it uses dhclient to obtain an IP address via DHCP. The script first flushes any existing IP addresses. After that, it adds the IP addresses and netmasks to the HQ and BR interfaces. Proper configuration of network interfaces is the core of any network setup. Pay attention to interface names, IP addresses, and netmasks to avoid network connectivity issues.
Setting up NAT (Network Address Translation)
Finally, let's configure Network Address Translation (NAT). NAT is a crucial step for your ISP as it allows your private network (HQ and BR) to access the internet through a single public IP address. The script supports two methods of NAT configuration: nftables (preferred) and iptables. If nftables is available, the script sets up the NAT rules using nft. The nftables configuration is stored in /etc/nftables.conf and enables NAT for traffic originating from the HQ and BR networks. If nftables is not available, the script falls back to iptables. In this case, the script sets up the NAT rules using iptables and stores them in /etc/iptables/rules.v4. It also creates a systemd service to restore these rules on boot. NAT configuration ensures that all the traffic from your internal networks can reach the internet, and the responses are correctly routed back. Proper NAT configuration is essential for internet access from your private network.
Final Steps and Verification
Once the script finishes running, your ISP setup is complete. However, you should still verify everything. Test the internet connection by pinging a public address. Verify the routing by pinging between your HQ and BR networks. Make sure everything works as expected. If something goes wrong, double-check all the parameters you entered, and examine the logs for any errors. Also, ensure that the firewall is not blocking the traffic. With everything set up and verified, you are ready to use your ALT JeOS as an ISP. Congratulations!
Troubleshooting Tips and Common Issues
If you run into trouble, don't panic! Here are a few troubleshooting tips: check your network settings, verify your firewall rules, and examine the logs. Check your network settings: Double-check that your IP addresses, subnets, and gateway are correct. Also, ensure the interfaces are up and running. Verify your firewall rules: Make sure that your firewall rules are not blocking any necessary traffic. Examine the logs: The logs can provide valuable information about what went wrong. Pay attention to any error messages. By following these steps, you should be able to resolve any issues. Remember, setting up an ISP can be complex, so don't be afraid to ask for help! There are tons of online resources and communities where you can find assistance. Good luck, and have fun setting up your ISP!