1Net::BGP(3) User Contributed Perl Documentation Net::BGP(3)
2
6 Net::BGP - Border Gateway Protocol version 4 speaker/listener library
7
9 use Net::BGP::Process;
10 use Net::BGP::Peer;
11 $bgp = Net::BGP::Process->new();
13 $peer = Net::BGP::Peer->new(
14 Start => 1,
15 ThisID => '10.0.0.1',
16 ThisAS => 64512,
17 PeerID => '10.0.0.2',
18 PeerAS => 64513
19 );
20 $bgp->add_peer($peer);
22 $peer->add_timer(\&my_timer_callback, 60);
23 $bgp->event_loop();
24
26 This module is an implementation of the BGP-4 inter-domain routing
27 protocol. It encapsulates all of the functionality needed to establish
28 and maintain a BGP peering session and exchange routing update
29 information with the peer. It aims to provide a simple API to the BGP
30 protocol for the purposes of automation, logging, monitoring, testing,
31 and similar tasks using the power and flexibility of perl. The module
32 does not implement the functionality of a RIB (Routing Information
33 Base) nor does it modify the kernel routing table of the host system.
34 However, such operations could be implemented using the API provided by
35 the module.
36 The module takes an object-oriented approach to abstracting the
38 operations of the BGP protocol. It supports multiple peering sessions
39 and each peer corresponds to one instance of a Net::BGP::Peer object.
40 The details of maintaining each peering session are handled and
41 coordinated by an instance of a Net::BGP::Process object. BGP UPDATE
42 messages and the routing information they represent are encapsulated by
43 Net::BGP::Update objects. Whenever protocol errors occur and a BGP
44 NOTIFICATION is sent or received, programs can determine the details of
45 the error via Net::BGP::Notification objects.
46 The module interacts with client programs through the paradigm of
48 callback functions. Whenever interesting protocol events occur, a
49 callback function supplied by the user is called and information
50 pertaining to the event is passed to the function for examination or
51 action. For instance, whenever an UPDATE message is received from a
52 peer, the module handles the details of decoding the message,
53 validating it, and encapsulating it in an object and passing the object
54 to the specific callback function supplied by the user for UPDATE
55 message handling. The callback function is free to do whatever with the
56 object - it might send a Net::BGP::Update object to other peers as
57 UPDATE messages, perhaps after modifying some of the UPDATE attributes,
58 log the routing information to a file, or do nothing at all. The
59 possibilities for implementing routing policy via such a mechanism are
60 limited only by the expressive capabilities of the perl language. It
61 should be noted however that the module is intended for the uses stated
62 above and probably would not scale well for very large BGP meshes or
63 routing tables.
64 The module must maintain periodic protocol keep-alive and other
66 processes, so once control is passed to the module's main event loop,
67 control flow only passes back to user code whenever one of the callback
68 functions is invoked. To provide more interaction with user programs,
69 the module allows user timers to be established and called periodically
70 to perform further processing. Multiple timers may be established, and
71 each is associated with a single peer. Whenever the timers expire, a
72 user supplied function is called and the timer is reset. The timer
73 callback functions can perform whatever actions are necessary - sending
74 UPDATEs, modifying the state of the peering session, house-keeping,
75 etc.
76
78 The connection collision resolution code is broken. As currently
79 implemented, whenever a connection is received from a peer, the
80 Net::BGP::Peer object is cloned and each peer object proceeds through
81 the session establishment process until the collision resolution
82 procedure is reached. At this point, if the cloned object is chosen by
83 the collison resolution procedure, the original peer object is
84 destroyed, leaving the cloned object. Unfortunately, a user program
85 will only have a reference to the original peer object it created and
86 will have no way of accessing the cloned object. It is therefore
87 recommended that Net::BGP::Peer objects be instantiated with the Listen
88 parameter set to a false value. This prevents the peer object from
89 receiving connections from its BGP peer, although it will continue
90 actively attempting to establish sessions. This problem will be
91 addressed in a future revision of Net::BGP.
92 As an initial revision, the code has not been subjected to a thorough
94 security audit. It is possible and likely that exploitable code exists
95 in the packet decoding routines. Therefore, it is recommended that the
96 module only be used to establish peering sessions with trusted peers,
97 particularly if programs using the module will be run with root
98 priviliges (which is necessary if programs want to modify the kernel
99 routing table or bind to the well-known BGP port 179).
100
102 RFC 1771, and the perldocs for Net::BGP::Process, Net::BGP::Peer,
103 Net::BGP::Update, and Net::BGP::Notification
104
106 Stephen J. Scheck <sscheck@cpan.org>
107perl v5.34.0 2021-07-22 Net::BGP(3)