How to use the command 'bgpgrep' (with examples)

The command ‘bgpgrep’ is a tool that allows users to filter and print BGP (Border Gateway Protocol) data within MRT (Multi-Threaded Routing Toolkit) dumps. It supports reading files compressed with gzip, bzip2, and xz. ‘bgpgrep’ is a part of the ubgpSuite, a suite of open-source BGP analysis tools.

Use case 1: Output all routes

Code:

bgpgrep master6.mrt

Motivation: This use case is useful when you need to analyze all the BGP routes within an MRT dump file. By using this command, you can easily obtain a comprehensive list of all the routes contained in the file.

Explanation:

• bgpgrep is the command to execute.
• master6.mrt is the filename of the MRT dump file.

Example output:

Route: 192.0.2.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

Route: 198.51.100.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

...

Use case 2: Output all routes received from a specific peer (AS number)

Code:

bgpgrep master4.mrt -peer 64498

Motivation: This use case is helpful for analyzing BGP routes received from a specific peer, identified by their Autonomous System (AS) number. It allows you to focus on the routes received from a specific source.

Explanation:

• bgpgrep is the command to execute.
• master4.mrt is the filename of the MRT dump file.
• -peer 64498 specifies that you want to filter for routes received from the peer with AS number 64498.

Example output:

Route: 192.0.2.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

Route: 203.0.113.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

...

Use case 3: Output all routes received from a specific peer (IP address)

Code:

bgpgrep master4.mrt.bz2 -peer 2001:db8:dead:cafe:acd::19e

Motivation: This use case is useful for filtering BGP routes received from a specific peer, identified by their IP address. It enables you to analyze the routes exchanged with a particular peer.

Explanation:

• bgpgrep is the command to execute.
• master4.mrt.bz2 is the filename of the compressed MRT dump file.
• -peer 2001:db8:dead:cafe:acd::19e specifies that you want to filter for routes received from the peer with the IP address “2001:db8:dead:cafe:acd::19e”.

Example output:

Route: 203.0.113.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

Route: 192.0.2.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

...

Use case 4: Output all routes with certain ASNs in their AS path

Code:

bgpgrep master6.mrt.bz2 -aspath '64498 64510'

Motivation: This use case is helpful when you want to filter BGP routes that contain specific Autonomous System Numbers (ASNs) in their AS path. It helps in identifying routes associated with specific networks.

Explanation:

• bgpgrep is the command to execute.
• master6.mrt.bz2 is the filename of the compressed MRT dump file.
• -aspath '64498 64510' specifies that you want to filter for routes with AS path containing the ASNs “64498” and “64510”.

Example output:

Route: 192.0.2.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

Route: 198.51.100.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510

...

Use case 5: Output all routes that lead to a specific address

Code:

bgpgrep master6.mrt.bz2 -supernet '2001:db8:dead:cafe:aef::5'

Motivation: This use case is useful for finding BGP routes that lead to a specific destination address. It helps in understanding the routing paths to a particular network or host.

Explanation:

• bgpgrep is the command to execute.
• master6.mrt.bz2 is the filename of the compressed MRT dump file.
• -supernet '2001:db8:dead:cafe:aef::5' specifies that you want to filter for routes that lead to the supernet IP address “2001:db8:dead:cafe:aef::5”.

Example output:

Route: 2001:db8:dead:cafe:aef::5/128
Next Hop: 203.0.113.1
AS Path: 64498 64510

...

Use case 6: Output all routes that have communities from a specific AS

Code:

bgpgrep master4.mrt -communities \( '64497:*' \)

Motivation: This use case is helpful when you want to identify BGP routes that have communities from a specific Autonomous System (AS). Communities are used to tag and manipulate BGP routes, and this command allows you to filter based on that information.

Explanation:

• bgpgrep is the command to execute.
• master4.mrt is the filename of the MRT dump file.
• -communities \( '64497:*' \) specifies that you want to filter for routes that have communities from AS 64497, matching any value.

Example output:

Route: 192.0.2.0/24
Next Hop: 203.0.113.1
AS Path: 64498 64510
Community: 64497:12345

Route: 192.0.2.128/25
Next Hop: 203.0.113.1
AS Path: 64498 64510
Community: 64497:54321

...

Conclusion:

The ‘bgpgrep’ command is a versatile tool for filtering and printing BGP data within MRT dumps. It allows you to analyze specific subsets of BGP routes based on various criteria, such as peer AS number, IP address, AS path, supernet, and communities. By understanding the different use cases and examples, you can effectively extract the necessary information from BGP data for analysis and troubleshooting purposes.