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Routing security, part 1

Routing protocols and their weaknesses

In order to communicate on the Internet at all, we must find a way to each other. I am not talking here about the path that ensures the perception of thoughts by the other party, although this is also a demanding discipline. I mean the path that ensures the delivery of packets or messages. This is based on routing algorithms that map the Internet. Or at least its immediate surroundings. Thanks to this, it is the routing protocols that govern the Internet. But their protection is currently dismal.

History of routing protocols

The original idea of ARPANET (October 29, 1969) was a fully distributed computer network, able to survive even a massive outage. It was not supposed to have any center. With the transition to TCP/IP on January 1, 1983, it practically became the Internet. But the beginnings were harder. Machines needed to know the path to other machines, so they used IMP (Interface Message Processor). Initially, these were static routing tables, later the possibility of dynamic updates (ARPANET Routing Algorithm) was added, which was actually a Link-state protocol. When TCP/IP was introduced, the transition to the newer protocols RIP and OSPF took place.

The exchange of information about the possible path of packets is a critical part of the infrastructure from a network perspective. However, from the beginning there has been a problem regarding the authenticity of the sender, integrity checking and under certain conditions, ensuring the confidentiality of the content of the transmitted information. If communication is redirected over a public channel via an attacker, it is possible to eavesdrop, analyze, or attack errors in protocols of other layers. Each of these methods offers the attacker certain attack vectors, so it is advisable to prevent such an attack.

Protection of routing information exchange

Publicly available routes can and do be attacked. In the case of routing information, this is sensitive data with a high impact. For these reasons, it is necessary to ensure a controlled exchange of information, where protection of authenticity, integrity and appropriate authorization must be ensured. There are several methods for these steps that can be combined:

  • Verification of the counterparty with a password (authentication)
  • Verification of the integrity of the transmitted information (MAC)
  • Verification of authenticity (it is possible to provide proof of the trustworthiness of the information)
  • Limiting the authorization to provide or receive the information, i.e. the form of AC

Due to the limitations of routing algorithms, it is advisable to support the control of the distribution of this information using ACL. A check for correct ACL functionality should always be part of the deployment, some devices suffer from interesting communication control issues. In general, procedures using authorization (ACL) can be divided into the following groups:

  • Neighbor filtering: who is my neighbor, i.e. who can send me data.
  • Prefix filtering: what can my neighbor provide me, i.e. what ranges or networks.
  • Route Origin: rPKI determines whether a given ASN range can provide prefix information. That is, whether it is allowed to publish given ranges because it has an ownership relationship to them.
  • Control plane protection using filters for rate limit, max-prefix, TTL security, CoPP (Control Plane Policing). The control plane itself actually manages the network, but does not participate in normal traffic. It only handles its mapping and setting up routes. In order to protect router resources (memory, CPU), it is necessary to address various restrictions filtering possible malicious traffic. The goal is to ensure the safety and accessibility of the routes.

Basic types of routing protocols

For the following information to make sense, it is necessary to state how the basic types of routing algorithms differ.

Distance-vector
A router knows its directly connected neighbors and for remote networks it only knows the best known next hop and the corresponding metric, in other words it uses the distance metric and the vector (direction). Thanks to the information from neighboring routers, it is able to calculate the best known metric for individual target networks. The route vector determines the direction through which communication is necessary. The distance metric can be, for example, the number of hops between routers. The vector determines the neighbor (next hop), or the output interface through which we can reach the destination. Each distance-vector protocol defines its own metric and method of determining the next hop, a combination of bandwidth, latency, route delay and other properties can be used as the metric. The protocol is usually updated at regular intervals, on the other hand, it has lower memory requirements. The protocol thus knows only the information that is reported to it by its neighbors, and uses the Bellman-Ford algorithm or its derivatives to determine the route. Mechanisms such as split horizon, route poisoning, poison reverse, hold-down timers are used to protect against the formation of loops.

Link-state
The router knows the topology of the entire area and calculates the best route itself, and in reality it uses the link state and its costs to determine the optimal path. Each link is assigned a metric (cost), which is usually derived from the line speed, for example. If necessary, the administrator can modify it to influence the choice and priority of routes. Based on the exchange of this information, each router creates a network topology database and uses the SPF (Dijkstra) algorithm to calculate the route with the lowest total cost. The route selection is thus determined by the lowest cost for the entire route, based on the protocol definition. Information about the topology is normally propagated when the network state changes, rather than by regularly broadcasting the entire routing table, which reduces the cost of operation. On the other hand, the router must maintain the entire network structure in memory, which increases the memory requirements accordingly.

Overview of Routing Protocols

Currently, certain types of routing protocols are available within IPv4 and IPv6. They can be classified roughly as follows.

ProtocolIPv4IPv6ClassInterior/ExteriorPrinciple
RIP v1YesNoControl-planeIGPDistance-vector
RIP v2YesNoControl-planeIGPDistance-vector
RIPngNoYesControl-planeIGPDistance-vector
OSPFv2YesNoControl-planeIGPLink-state
OSPFv3YesYesControl-planeIGPLink-state
IS-ISYesYesControl-planeIGPLink-state
IGRPYesNoControl-planeIGPDistance-vector
EIGRPYesYesControl-planeIGPAdvanced distance-vector
EGPYesNoControl-planeEGPDistance-vector
BGPYesYesControl-planeEGPPath-vector

BGP protocol and its variants

The actual BGP protocol mentioned here is not actually the only protocol. It is to some extent a group of protocols. Alternatively, it can be viewed as a protocol with the possibility of using specific configurations, which can be designated as subprotocols with specific properties. Therefore, they are often referred to by their own name.

ProtocolIPv4IPv6ClassInterior/ExteriorPrinciple
BGPYesYesControl-planeEGPPath-vector
eBGP (BGP)YesYesControl-planeEGPPath-vector
iBGP (BGP)YesYesControl-planeEGPPath-vector
mBGP/MP-BGP (BGP)YesYesControl-planeEGPPath-vector + multiprotocol extension
MBGP (BGP)YesYesControl-planeControl-planePath-vector + multicast AFI/SAFI

First Hop Redundancy

The advent of IPv6 brought further development, in this case development in the area of automatic definition of backup routes. The protocol detects and sets the route using Router Advertisement and then uses FHRP (First Hop Redundancy Protocol) to create the mentioned backup route. The entire IPv6 is strongly self-configuring and therefore it is necessary to ensure automatic configuration for backup routes for fault tolerance. In this case, it is not directly a routing protocol, but rather a service protocol.

ProtocolIPv4IPv6ClassInterior/ExteriorPrinciple
HSRP v1YesNoFirst-hop redundancyN/AActive/standby
HSRP v2YesYesFirst-hop redundancyN/AActive/standby
VRRP v2YesNoFirst-hop redundancyN/AMaster/backup
VRRP v3YesYesFirst-hop redundancyN/AMaster/backup
GLBPYesNoFirst-hop redundancyN/ALoad balancing + redundancy

Protocol communication method

A subtle addition could be the introduction of other properties of the protocol that may be meaningful from the point of view of network traffic management. This is a rough overview that should show the issues of routing protocol management.

ProtocolUnicastBroadcastMulticastPoint to PointPoint to MultiPointCIDR
RIP v1NoYes (UDP/520)NoNoYesNo
RIP v2OptionalNoL3: (UDP/520)
224.0.0.9
NoYesYes
RIPngOptionalNoL3: (UDP/521)
ff02::9
NoYesYes
OSPFv1NoNoL3: (IP/89)
224.0.0.5 (AllSPFRouters)
224.0.0.6 (AllDRouters)
YesYesPartial
OSPFv2NoNoL3: (IP/89)
224.0.0.5 (AllSPFRouters)
224.0.0.6 (AllDRouters)
YesYesYes
OSPFv3NoNoL3: (IP/89)
ff02::5 (AllSPFRouters)
ff02::6 (AllDRouters)
YesYesYes
IS-ISNoNoL2:
01:80:C2:00:00:14 (L1)
01:80:C2:00:00:15 (L2)
YesYesYes
IGRPNoYes (IP/9)NoNoYesNo
EIGRPYes (IP/88)NoL3: (IP/88)
224.0.0.10
YesYesYes
EGPYes (IP/8)NoNoYesNoNo
BGPYes (TCP/179)NoNoYesNoYes
eBGPYes (TCP/179)NoNoYesNoYes
iBGPYes (TCP/179)NoNoYesNoYes
MP-BGP (mBGP)Yes (TCP/179)NoNoYesNoYes
MBGPYes (TCP/179)NoNoYesNoYes
HSRP v1NoNoL3: (UDP/1985)
224.0.0.2 (HSRP group)
NoYesN/A
HSRP v2NoNoL3: (UDP/1985)
224.0.0.102 (HSRPv2 group)
NoYesN/A
VRRP v2NoNoL3: (IP/112)
224.0.0.18 (VRRP routers)
NoYesN/A
VRRP v3NoNoL3: (IP/112)
224.0.0.18 (IPv4)
ff02::12 (IPv6)
NoYesN/A
GLBPNoNoL3: (UDP/3222)
224.0.0.102 (GLBP group)
NoYesN/A

End of Part One

The first part describes the algorithms themselves, the second focuses on participant verification and the integrity of transmitted messages.

References:

  1. RIP Version 1.
    Source: https://www.rfc-editor.org/
  2. RIP Version 2.
    Source: https://www.rfc-editor.org/
  3. RIPng for IPv6.
    Source: https://www.rfc-editor.org/
  4. OSPF Version 1.
    Source: https://www.rfc-editor.org/
  5. OSPF Version 2.
    Source: https://www.rfc-editor.org/
  6. OSPFv3 for IPv6.
    Source: https://www.rfc-editor.org/
  7. IS-IS routing protocol.
    Source: https://www.rfc-editor.org/
  8. Cisco Interior Gateway Routing Protocol (IGRP) documentation.
    Source: https://www.cisco.com/
  9. Enhanced Interior Gateway Routing Protocol (EIGRP).
    Source: https://www.cisco.com/
  10. Exterior Gateway Protocol.
    Source: https://www.rfc-editor.org/
  11. Border Gateway Protocol Version 4.
    Source: https://www.rfc-editor.org/
  12. External BGP (BGP between autonomous systems).
    Source: https://www.rfc-editor.org/
  13. Internal BGP (BGP within one autonomous system).
    Source: https://www.rfc-editor.org/
  14. Multiprotocol Extensions for BGP-4 (MP-BGP / mBGP).
    Source: https://www.rfc-editor.org/
  15. Multicast BGP (MBGP).
    Source: https://www.rfc-editor.org/
  16. Hot Standby Router Protocol Version 1 (Cisco).
    Source: https://www.cisco.com/
  17. Hot Standby Router Protocol Version 2 (Cisco).
    Source: https://www.cisco.com/
  18. Virtual Router Redundancy Protocol Version 2.
    Source: https://www.rfc-editor.org/
  19. Virtual Router Redundancy Protocol Version 3.
    Source: https://www.rfc-editor.org/
  20. Gateway Load Balancing Protocol (Cisco).
    Source: https://www.cisco.com/

Autor článku:

Jan Dušátko
Jan Dušátko

Jan Dušátko has been working with computers and computer security for almost a quarter of a century. In the field of cryptography, he has cooperated with leading experts such as Vlastimil Klíma or Tomáš Rosa. Currently he works as a security consultant, his main focus is on topics related to cryptography, security, e-mail communication and Linux systems.

1. Introductory Provisions

1.1. These General Terms and Conditions are, unless otherwise agreed in writing in the contract, an integral part of all contracts relating to training organised or provided by the trainer, Jan Dušátko, IČ 434 797 66, DIČ 7208253041, with location Pod Harfou 938/58, Praha 9 (next as a „lector“).
1.2. The contracting parties in the general terms and conditions are meant to be the trainer and the ordering party, where the ordering party may also be the mediator of the contractual relationship.
1.3. Issues that are not regulated by these terms and conditions are dealt with according to the Czech Civil Code, i.e. Act No.89/2012 Coll.
1.4. All potential disputes will be resolved according to the law of the Czech Republic.

2. Creation of a contract by signing up for a course

2.1. Application means unilateral action of the client addressed to the trainer through a data box with identification euxesuf, e-mailu with address register@cryptosession.cz or register@cryptosession.info, internet pages cryptosession.cz, cryptosession.info or contact phone +420 602 427 840.
2.2. By submitting the application, the Client agrees with these General Terms and Conditions and declares that he has become acquainted with them.
2.3. The application is deemed to have been received at the time of confirmation (within 2 working days by default) by the trainer or intermediary. This confirmation is sent to the data box or to the contact e-mail.
2.4. The standard time for registration is no later than 14 working days before the educational event, unless otherwise stated. In the case of a natural non-business person, the order must be at least 28 working days before the educational event.
2.5. More than one participant can be registered for one application.
2.6. If there are more than 10 participants from one Client, it is possible to arrange for training at the place of residence of the intermediary or the Client.
2.7. Applications are received and processed in the order in which they have been received by the Provider. The Provider immediately informs the Client of all facts. These are the filling of capacity, too low number of participants, or any other serious reason, such as a lecturer's illness or force majeure. In this case, the Client will be offered a new term or participation in another educational event. In the event that the ordering party does not agree to move or participate in another educational event offered, the provider will refund the participation fee. The lack of participants is notified to the ordering party at least 14 days before the start of the planned term.
2.8. The contract between the provider and the ordering party arises by sending a confirmation from the provider to the ordering party.
2.9. The contract may be changed or cancelled only if the legal prerequisites are met and only in writing.

3. Termination of the contract by cancellation of the application

3.1. The application may be cancelled by the ordering party via e-mail or via a data mailbox.
3.2. The customer has the right to cancel his or her application for the course 14 days before the course takes place without any fees. If the period is shorter, the subsequent change takes place. In the interval of 7-13 days, an administrative fee of 10% is charged, cancellation of participation in a shorter interval than 7 days then a fee of 25%. In case of cancellation of the application or order by the customer, the possibility of the customer's participation in an alternative period without any additional fee is offered. The right to cancel the application expires with the implementation of the ordered training.
3.3. In case of cancellation of the application by the trainer, the ordering party is entitled to a full refund for the unrealized action.
3.4. The ordering party has the right to request an alternative date or an alternative training. In such case, the ordering party will be informed about all open courses. The alternative date cannot be enforced or enforced, it depends on the current availability of the course. If the alternative training is for a lower price, the ordering party will pay the difference. If the alternative training is for a lower price, the trainer will return the difference in the training prices to the ordering party.

4. Price and payment terms

4.1. By sending the application, the ordering party accepts the contract price (hereinafter referred to as the participation fee) indicated for the course.
4.2. In case of multiple participants registered with one application, a discount is possible.
4.3. The participation fee must be paid into the bank account of the company held with the company Komerční banka č. 78-7768770207/0100, IBAN:CZ5301000000787768770207, BIC:KOMBCZPPXXX. When making the payment, a variable symbol must be provided, which is indicated on the invoice sent to the client by the trainer.
4.4. The participation fee includes the provider's costs, including the training materials. The provider is a VAT payer.
4.5. The client is obliged to pay the participation fee within 14 working days of receipt of the invoice, unless otherwise stated by a separate contract.
4.6. If the person enrolled does not attend the training and no other agreement has been made, his or her absence is considered a cancellation application at an interval of less than 7 days, i.e. the trainer is entitled to a reward of 25% of the course price. The overpayment is returned within 14 days to the sender's payment account from which the funds were sent. Payment to another account number is not possible.
4.7. An invoice will be issued by the trainer no later than 5 working days from the beginning of the training, which will be sent by e-mail or data box as agreed.

5. Training conditions

5.1. The trainer is obliged to inform the client 14 days in advance of the location and time of the training, including the start and end dates of the daily programme.
5.2. If the client is not a student of the course, he is obliged to ensure the distribution of this information to the end participants. The trainer is not responsible for failure to comply with these terms and conditions.
5.2. By default, the training takes place from 9 a.m. to 5 p.m. at a predetermined location.
5.3. The trainer can be available from 8 a.m. to 9 a.m. and then from 17 a.m. to 6 p.m. for questions from the participants, according to the current terms and conditions.
5.4. At the end of the training, the certificate of absorption is handed over to the end users.
5.5. At the end of the training, the end users evaluate the trainer's approach and are asked to comment on the evaluation of his presentation, the manner of presentation and the significance of the information provided.

6. Complaints

6.1. If the participant is grossly dissatisfied with the course, the trainer is informed of this information.
6.2. The reasons for dissatisfaction are recorded in the minutes in two copies on the same day. One is handed over to the client and one is held by the trainer.
6.3. A statement on the complaint will be submitted by e-mail within two weeks. A solution will then be agreed within one week.
6.4. The customer's dissatisfaction may be a reason for discontinuing further cooperation, or financial compensation up to the price of the training, after deduction of costs.

7. Copyright of the provided materials

7.1. The training materials provided by the trainer in the course of the training meet the characteristics of a copyrighted work in accordance with Czech Act No 121/2000 Coll.
7.2. None of the training materials or any part thereof may be further processed, reproduced, distributed or used for further presentations or training in any way without the prior written consent of the trainer.

8. Liability

8.1. The trainer does not assume responsibility for any shortcomings in the services of any third party that he uses in the training.
8.2. The trainer does not assume responsibility for injuries, damages and losses incurred by the participants in the training events or caused by the participants. Such costs, caused by the above circumstances, shall be borne exclusively by the participant in the training event.

9. Validity of the Terms

9.1 These General Terms and Conditions shall be valid and effective from 1 October 2024.

Consent to the collection and processing of personal data

According to Regulation (EU) No 2016/679 of the European Parliament and of the Council on the protection of individuals with regard to the processing of personal data and on the free movement of such data and repealing Directive 95/46/EC (General Data Protection Regulation, hereinafter referred to as "the Regulation"), the processor xxx (hereinafter referred to as "the Controller") processes personal data. Individual personal data that are part of the processing during specific activities at this web presentation and in the course of trade are also broken down.
Although the collection of data is ubiquitous, the operation of this website is based on the right to privacy of each user. For this reason, the collection of information about users takes place to the extent absolutely necessary and only if the user decides to contact the operator. We consider any further collection and processing of data unethical.

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This website does not collect any cookies. The site does not use any analytical scripts of third parties (social networks, cloud providers). For these reasons, an option is also offered for displaying the map in the form of a link, where the primary source is OpenStreet and alternatives then the frequently used Maps of Seznam, a.s., or Google Maps of Google LLC Inc. The use of any of these sources is entirely at the discretion of the users of this site. The administrator is not responsible for the collection of data carried out by these companies, does not provide them with data about users and does not cooperate on the collection of data.
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In case of an interest in the order form, the form contains more data, i.e. name, surname, e-mail and contact details for the organisation. These data are intended only for this communication, corresponding to the address of the user and are kept for one year, unless the user determines otherwise. In the event that a business relationship is concluded on the basis of this order, only the information required by Czech law on the basis of business relations (company name and address, bank account number, type of course and its price) will continue to be kept by the administrator.

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Within the course, a course completion document is issued by the processor. This document contains the following data: student's name and surname, the name and date of the course completion and the employer's name. The information is subsequently used for the creation of a linear hash tree (non-modifiable record). This database contains only information about the provided names and company names, which may or may not correspond to reality and is maintained by the processor for possible re-issuance or verification of the document's issuance.

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The customer or visitor of this website has the possibility to request information about the processing of personal data, the right to request access to personal data, or the right to request the correction or deletion of any data held about him. In the case of deletion, this requirement cannot be fulfilled only if it is not data strictly necessary in the course of business. The customer or visitor of this website also has the right to obtain explanations regarding the processing of his personal data if he finds out or believes that the processing is carried out in violation of the protection of his private and personal life or in violation of applicable legislation, and the right to request removal of the resulting situation and to ensure the correction.
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The customer/visitor has the right to file a complaint against the processing of personal data with the supervisory authority, which is the Office for Personal Data Protection.