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https://github.com/exa-networks/exabgpA programmable BGP implementation that allows users to control BGP networks via Python scripts or external programs through a JSON API. Designed for DDoS mitigation, traffic engineering, and anycast management, ExaBGP focuses on protocol implementation without manipulating the local FIB. Documentation covers installation via pip, Docker, and Debian packages, as well as RIB benchmarking, API functional testing, and a BGP Route Reflector lab for AS-PATH based filtering.
ExaBGP is a BGP routing protocol implementation designed for the control plane. It focuses on BGP protocol control and does NOT perform FIB (Forwarding Information Base) manipulation.
Common use cases include:
ExaBGP is undergoing a security hardening process focused on two main areas: hardening the configuration/API layers against malformed input and preventing information leakage through error messages.
src/exabgp/configuration/ using type, range, format, and semantic validation.src/exabgp/reactor/api/command/."invalid command" instead of detailed parsing errors).ExaBGP is a Software Defined Networking (SDN) tool that allows engineers to control networks from commodity servers using the BGP protocol.
Key Capabilities:
This document outlines the technical plan for implementing neighbor naming and aliasing in ExaBGP. The goal is to allow users to assign human-readable names (aliases) to BGP neighbors, which can then be used in configuration, API commands, and registry lookups instead of relying solely on IP addresses or connection identifiers.
| Component | Change |
|---|---|
src/exabgp/bgp/neighbor/neighbor.py | Add alias field and include it in JSON output |
src/exabgp/bgp/neighbor/settings.py | Add alias to neighbor settings |
src/exabgp/configuration/neighbor/__init__.py | Add name to the configuration schema |
src/exabgp/configuration/neighbor/parser.py | Add validation for neighbor names |
src/exabgp/reactor/loop.py | Add a name registry to track neighbors by name |
src/exabgp/configuration/configuration.py | Implement validation to ensure name uniqueness |
src/exabgp/reactor/api/command/limit.py | Support name-based selectors for limiting commands |
src/exabgp/reactor/api/command/peer.py | Add commands for managing neighbor names |
src/exabgp/reactor/api/command/registry.py | Register new name-related commands |
src/exabgp/reactor/api/command/neighbor.py | Include names in the show command output |
ExaBGP is a BGP implementation designed for network engineers and developers to interact with BGP networks via a simple API using Python scripts or external programs.
Key Difference: Unlike traditional BGP daemons (such as BIRD or FRRouting), ExaBGP does not manipulate the Forwarding Information Base (FIB). It focuses purely on BGP protocol implementation and provides an API for external processes to control routing.
_watchdog dictionary. Instead, they are moved between the + and - sub-dictionaries. This behavior is a known characteristic of the current implementation.To reduce nesting and improve readability, follow these patterns:
if/else blocks.continue instead of deep nesting inside loops.return or continue), the main logic should be at the base indentation level of the function/loop.# Early return pattern
def process_message(self, data):
if not data:
return None
if len(data) < HEADER_LEN:
raise InvalidMessage('insufficient data')
return self._parse(data)
# Loop pattern
for item in items:
if skip_condition(item):
continue
# Main logic is de-indented
process_item(item)ExaBGP has transitioned from string-based action dispatch to an explicit enum-based system for configuration schemas. While the action field in schemas remains a str for backward compatibility, new code and schema definitions should use the explicit target, operation, and key fields provided by the Leaf and LeafList classes. This enables better IDE autocompletion and more robust validation.
Key Enums:
ActionTarget: Defines what the action is targeting.ActionOperation: Defines the operation to perform (e.g., SET, APPEND).ActionKey: Defines the specific key or dimension of the action.Note on Leaf vs LeafList defaults:
Leaf defaults to the SET operation.LeafList defaults to the APPEND operation.The lab uses a Filter API Process (scripts/filter_api.py) that communicates with ExaBGP via STDIN/STDOUT using JSON. The filter examines the aspath attribute of incoming routes and applies the following logic:
| AS in Path | Organization | Action |
|---|---|---|
| 15169 | Forward to Client1 (127.0.0.2) | |
| 8075 | Microsoft | Forward to Client2 (127.0.0.3) |
| 13335 | Cloudflare | Dropped |
| 19281 | Quad9 | Dropped |
Message Flow Example:
UPDATE with AS-PATH [15169, 65001].{"type": "update", "nlri": "8.8.8.0/24", "attributes": {"aspath": [{"asns": [15169, 65001]}]}}announce route 8.8.8.0/24 next-hop 10.0.0.1 as-path [ 15169 65001 ]UPDATE to the designated client.The group command allows you to batch multiple BGP announcements (or withdrawals) into a single BGP UPDATE message. This is useful for reducing the total number of UPDATE messages sent during bulk operations, ensuring atomic updates, and achieving exact wire-format reproduction for multi-NLRI (Network Layer Reachability Information) updates.
group end is reached (or a newline in single-line syntax), ExaBGP groups the buffered commands by compatible attributes (family, next-hop, and other attributes).### Multi-line Example
```text
group start
announce ipv4 mcast-vpn shared-join rp 10.99.199.1 group 239.251.255.228 rd 65000:99999 source-as 65000 next-hop 10.10.6.3 extended-community [target:192.168.94.12:5]
announce ipv4 mcast-vpn source-join source 10.99.12.2 group 239.251.255.228 rd 65000:99999 source-as 65000 next-hop 10.10.6.3 extended-community [target:192.168.94.12:5]
group endIn ExaBGP's IP implementation, the afi (Address Family Identifier) attribute behaves differently depending on the specific IP class being used. This is handled via attribute shadowing to maintain compatibility between class constants and instance variables:
IPv4 and IPv6: The afi attribute is a class attribute (e.g., AFI.ipv4 or AFI.ipv6).IPSelf: The afi attribute is an instance variable set during __init__ (can be either ipv4 or ipv6).IP.NoNextHop: The afi attribute is set to AFI.undefined.When working with these classes, be aware that IPv4 and IPv6 use the attribute at the class level, while other subclasses may rely on instance-specific values.
ExaBGP uses an interning strategy to reduce the memory footprint of the Routing Information Base (RIB). Instead of duplicating identical objects (NLRI, Attributes, NextHops) across multiple neighbors, the system uses global pools to share references to immutable objects.
NLRIPool, AttributePool) maintain a WeakValueDictionary of existing objects. When a new object is created, the system checks the pool using a unique index (via .index()). If a match exists, the cached instance is returned instead of the new one.OutgoingRIB is updated to store references to these interned objects rather than full Route copies, significantly reducing memory usage when many neighbors receive identical updates.