Automating BGP Filtering with bgpq4

BGP filtering plays a vital role in controlling the flow of network traffic and preventing routing issues. However, crafting and maintaining extensive filtering configurations can be a time-consuming task for network administrators. Thankfully, the bgpq4 utility comes to the rescue.

What is bgpq4?

bgpq4 is a powerful automation tool for generating configurations such as prefix-lists, access-lists, policy-statement terms, and as-path lists based on Internet Routing Registry (IRR) data. By leveraging IRR data, bgpq4 simplifies the process of creating and updating filtering configurations, saving network administrators valuable time and effort.

Generating Filtering Configurations

With bgpq4, you have a wide range of options for generating filtering configurations. Some of the key options include:

• Generating IPv4 or IPv6 prefix/access-lists: bgpq4 can generate filtering configurations for both IPv4 and IPv6 networks.
• Aggregating prefix-lists: Use the ‘-A’ flag to aggregate prefix-lists and make them more compact.
• Formatting options: bgpq4 supports various output formats, including Cisco, Juniper, Nokia, OpenBGPD, and more. You can also define your own user-defined format.
• Extra match conditions: Specify additional match conditions for Juniper route-filters using the ‘-M’ flag.
• Source selection: Choose specific sources from the IRR database using the ‘-S’ flag, ensuring you trust the data from reliable sources.

To understand how these options work in practice, let’s look at a few examples.

Example 1: Generating a Juniper Prefix-Filter

Suppose we want to generate a named juniper prefix-filter for AS20597. We can achieve this with the following command:

bash
bgpq4 -Jl eltel AS20597

The output will be a policy-options configuration block for Juniper devices that includes the generated prefix-list for AS20597.

Example 2: Aggregating Prefixes for Cisco

If we want to use Cisco devices and make our prefix-filter more compact, we can use the aggregation flag (-A). For example:

bash
bgpq4 -Al eltel AS20597

The output will be a Cisco configuration with an aggregated prefix-list for AS20597, where specific prefixes are consolidated into a single entry.

Example 3: Advanced Juniper Policy-Options

For Juniper devices, we can generate more advanced policy-options configurations by utilizing additional flags. In this example, we include extra match conditions (-M), specify prefix-length ranges (-r, -R), and use hierarchical names:

bash
bgpq4 -AJEl eltel/specifics -r 29 -R 32 -M "community blackhole" AS20597

The output will be a policy-options configuration for Juniper devices that allows specific prefixes with prefix-lengths between /29 and /32 for eltel networks if they match the specified community blackhole.

User-Defined Formatting

If you want to generate configurations for programs or systems other than routers, bgpq4 provides user-defined formatting options. You can define your own format string and utilize format sequences, such as %n for network, %l for mask length, %A for aggregate high mask length, and more. For example:

bash
bgpq4 -F "ipfw add pass all from %n/%l to any\n" as3254

The output will be a custom configuration in the specified format, where each line represents an ipfw rule.

Trusting Reliable Data Sources

When working with bgpq4, it’s crucial to trust reliable data sources. By default, bgpq4 trusts data from all databases mirrored into NTT’s IRR service. However, it’s best to limit the database sources to those you trust, such as RIR databases (AFRINIC, ARIN, APNIC, LACNIC, and RIPE) that have accurate information about allocated address space.

To limit the database sources, you can use the ‘-S’ flag or specify the source using the “::” notation. Be cautious when using non-authoritative databases like ARIN-NONAUTH and RIPE-NONAUTH, as they may contain stale data.

Building and Testing bgpq4

If you want to build bgpq4 from the source code, you can follow the provided instructions. The autotools-based build system makes it easy to configure, compile, and install the software.

To ensure the correctness of the output, bgpq4 includes tests. You can run the tests using the provided script and compare the output to the stored reference data. This ensures that the output remains consistent and reliable.

Join the BGPQ4 Community

bgpq4 is an actively developed and maintained project with contributions from various contributors. If you want to learn more, collaborate, or seek assistance, here are some resources:

• bgpq4 on GitHub: Explore the bgpq4 repository for the latest updates and documentation.
• NLNOG’s BGP Filter Guide: Discover a comprehensive guide on BGP filtering, including best practices and examples.
• BGPQ4 Mailing List: Join the bgpq4 mailing list to engage with other users and stay up to date with the latest discussions.

bgpq4 is a powerful tool that simplifies BGP filtering automation. By leveraging IRR data and providing various options and formats, bgpq4 enables network administrators to efficiently manage and maintain filtering configurations. Start using bgpq4 today and streamline your BGP filtering process.