DOCSLIB.ORG

DNS for Massive-Scale Command and Control Kui Xu Member, IEEE, Patrick Butler, Sudip Saha, Danfeng (Daphne) Yao Member, IEEE

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
DNS for Massive-Scale Command and Control Kui Xu Member, IEEE, Patrick Butler, Sudip Saha, Danfeng (Daphne) Yao Member, IEEE JOURNAL OF LATEX CLASS FILES, VOL. 6, NO. 1, JANUARY 2007 1 DNS for Massive-Scale Command and Control Kui Xu Member, IEEE, Patrick Butler, Sudip Saha, Danfeng (Daphne) Yao Member, IEEE Abstract—Attackers, in particular botnet controllers, use stealthy messaging systems to set up large-scale command and control. In order to systematically understand the potential capability of attackers, we investigate the feasibility of using domain name service (DNS) as a stealthy botnet command-and-control channel. We describe and quantitatively analyze several techniques that can be used to effectively hide malicious DNS activities at the network level. Our experimental evaluation makes use of a two-month-long 4.6GB campus network dataset and 1 million domain names obtained from alexa.com. We conclude that the DNS-based stealthy command-and-control channel (in particular the codeword mode) can be very powerful for attackers, showing the need for further research by defenders in this direction. The statistical analysis of DNS payload as a countermeasure has practical limitations inhibiting its large-scale deployment. Index Terms—Network security, DNS security, botnet detection, and command and control. F 1 INTRODUCTION The decentralized nature of domain name systems (DNS) with a series of redundant servers potentially Botnet command and control (C&C) channel refers to provides an effective channel for covert communication the protocol used by bots and botmaster (i.e., botnet of a large distributed system, including botnets. To play controller) to communicate to each other, e.g., for bots the devil’s advocate, we focus on systematically ana- to receive new attack commands and updates from lyzing the feasibility of a pure DNS-based command- botmaster, or to submit stolen data. A C&C channel for a and-control 1. Such a study has never been reported botnet needs to be reliable, redundant, non-centralized, in the literature. Our C&C system is compatible with and easily disguised as legitimate traffic. Many botnet existing DNS infrastructure without enlisting any Web operators used the Internet Relay Chat protocol (IRC) or special-purpose servers. The DNS channel is aided by or HTTP servers to pass information. Botnet operators being a high traffic channel such that data can be easily constantly explore new stealthy communication mech- hidden. As virtually anyone can create and register their anisms to evade detection. HTTP-based command and own domain names (if available) and DNS servers, it is control is difficult to distinguish from legitimate Web a system that can be easily infiltrated by hackers and traffic. The feasibility of email as a stealthy botnet com- botnet operators. mand and control protocol was studied by researchers DNS tunneling is a technique known for transmit- in [29]. In this paper, we systematically investigate the ting arbitrary data via DNS protocol, e.g., DNScat and feasibility of solely using Domain Name System (DNS) DeNiSe. One application of DNS tunneling is to bypass queries for botnet command and control. DNS provides firewalls, as both inbound and outbound DNS con- a distributed infrastructure for storing, updating, and nections are usually allowed by organizational firewall disseminating data that conveniently fits the need for rules. Because DNS is often overlooked in current secu- a large-scale command and control system. The HTTP rity measures, it offers a command-and-control channel protocol is for the end-to-end communication between a that is unimpeded. Because nearly all traffic requires client and a server. In comparison, DNS provides not DNS to translate domain names to IP addresses and only a means of communication between computers, back, simple firewall rules cannot easily be created with- but also systematic mechanisms for naming, locating, out harming legitimate traffic. Recently, Dietrich and distributing, and caching resources with fault tolerance. colleagues reported Feederbot that used DNS as a These features of DNS may be utilized to fulfill a more communication channel for C&C traffic [5]. However, effective command-and-control system than what HTTP Feederbot fails to utilize any distributed storage and servers may provide. query mechanisms offered by DNS. This botnet simply tunnels its command and control traffic by sending it in • Xu, Butler, and Saha are currently Ph.D. candidates at Virginia Tech DNS format for the end-to-end communication between Department of Computer Science. • Yao is with the Department of Computer Science, Virginia Tech, Blacksburg bots and the bot master. The domains used by them are VA 24060. not registered and cannot be resolved. Email: see http://www.cs.vt.edu/user/yao While using DNS tunneling for command and control The preliminary version of this work appeared in the 9th International has been observed [13], it was still unclear how effec- Conference on Applied Cryptography and Network Security (ACNS ’11), Lecture Notes in Computer Science 6715, pages 238-254 [2]. This work was supported in part by National Science Foundation grants CNS-0831186, 1. Other C&C protocols (e.g., HTTP) also involve DNS queries for CAREER CNS-0953638, ARO grant STIR-450080, and NSF S2ERC. name translation, but they do not use DNS for command and control. JOURNAL OF LATEX CLASS FILES, VOL. 6, NO. 1, JANUARY 2007 2 tive and feasible to use DNS to maintain stealthy large Section 6. Conclusions and open problems are given in botnets. Specifically, three items to consider in order to Section 7. evade detection for attackers are 1) Query activities. When and how frequent do bots 2 COMMUNICATION MODES issue DNS queries to pull updates from or submit data to the bot master? How to modify the victim’s In this section, we describe protocols that pass mes- operating system to implement automatic query sages over the DNS between distributed entities, and strategies? illustrate the ease of setting up large-scale command- 2) Domain names. What domain names to use for com- and-control via DNS. We describe two forms of com- munication and how to synchronize the generation munication modes: codeword mode and tunneled mode. of new domain names between bots and the bot Codeword communication allows one-way communication master? from botmaster to a bot client, which is suitable for 3) DNS payload. How to evade the detection through issuing attack commands. Tunneled communication allows deep packet inspection by defenders on DNS pay- for the transmitting of arbitrary data in both directions load? between bot and botmaster, which may be used for both issuing commands and collecting stolen data. The former Our work systematic addresses these questions using only requires the ability to set a particular domain name system engineering, networking, and data mining tech- response, this could be done via any free DNS service, niques. Our technical contributions are summarized as while the latter requires setting up an authoritative follows. domain server. • We describe techniques for hiding query activities, The controller of the botnet first needs to create a including i) piggybacking query strategy – a bot blends domain or subdomain, which is administered from a its (outbound) DNS queries with legitimate DNS special DNS server. This DNS server waits for special queries and ii) exponentially distributed query strategy name lookups, which it then translates into incoming – a bot probabilistically distributes DNS queries data. The DNS server then responds with the appropri- so that inter-arrival times follow an exponential ate data using the agreed-upon semantics. We assume distribution. We demonstrate the ability for a bot that the botnet controller (i.e., botmaster) has access to to send piggybacking DNS traffic through traffic the authoritative domain name server for some domains sniffing in Linux. or sub-domains. Bots across the Internet frequently re- • For automatic domain flux, where the domain ceive commands and updates from a botmaster and names used for communications in the botnet are launch attacks accordingly, as well as submit stolen data changed frequently and in a synchronized fashion to the botmaster. We give brief background information across all bots and their controllers, we describe on DNS records. a practical automatic domain flux method with DNS Resources Records The DNS system allows a Markov chain, and experimentally evaluate it with name server administrator to associate different types of 1 million domain names from alexa.com. data with either a fully qualified domain name or an IP • Statistical methods can be used by defenders to address. To send a message to a bot, an adversary can detect anomalies in the content of DNS packets, store data in any one of these types of records. through comparing the probability distributions of • A record specifies an IP address for a given host normal DNS traffic and tunneling traffic. We evalu- name. ate these methods as countermeasures and point out • CNAME and MX records can point to textual data the practical limitations that hinder the large-scale representing the alias or mailing host of a particular deployment by defenders. host name. We perform comprehensive experiments to evaluate • TXT records are designed to store arbitrary textual the behaviors of proposed query strategies in terms data up to 255 characters. of how quickly new commands are disseminated to a • EDNS0 record allows storing up to a 1280 byte large number of bots. Our analysis utilizes a 4.6GB two- payload [24]. EDNS0 was introduced in RFC261 in month-long wireless network trace obtained from an order to extend the DNS protocol. When a capable organization. We conclude that the DNS-based botnet server or client encounters this field, it can decode command-and-control channel is feasible, powerful, and the packets, allowing several improvements to the difficult to detect and block. basic DNS protocol. These features include larger Organization We describe the basic DNS tunneling UDP packet size, a list of attribute value pairs, and mechanisms in Section 2.
Load more

Recommended publications
  • Configuring DNS
    Configuring DNS The Domain Name System (DNS) is a distributed database in which you can map hostnames to IP addresses through the DNS protocol from a DNS server. Each unique IP address can have an associated hostname. The Cisco IOS software maintains a cache of hostname-to-address mappings for use by the connect, telnet, and ping EXEC commands, and related Telnet support operations. This cache speeds the process of converting names to addresses. Note You can specify IPv4 and IPv6 addresses while performing various tasks in this feature. The resource record type AAAA is used to map a domain name to an IPv6 address. The IP6.ARPA domain is defined to look up a record given an IPv6 address. • Finding Feature Information, page 1 • Prerequisites for Configuring DNS, page 2 • Information About DNS, page 2 • How to Configure DNS, page 4 • Configuration Examples for DNS, page 13 • Additional References, page 14 • Feature Information for DNS, page 15 Finding Feature Information Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module. Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
    [Show full text]
  • Adopting Encrypted DNS in Enterprise Environments
    National Security Agency | Cybersecurity Information Adopting Encrypted DNS in Enterprise Environments Executive summary Use of the Internet relies on translating domain names (like “nsa.gov”) to Internet Protocol addresses. This is the job of the Domain Name System (DNS). In the past, DNS lookups were generally unencrypted, since they have to be handled by the network to direct traffic to the right locations. DNS over Hypertext Transfer Protocol over Transport Layer Security (HTTPS), often referred to as DNS over HTTPS (DoH), encrypts DNS requests by using HTTPS to provide privacy, integrity, and “last mile” source authentication with a client’s DNS resolver. It is useful to prevent eavesdropping and manipulation of DNS traffic. While DoH can help protect the privacy of DNS requests and the integrity of responses, enterprises that use DoH will lose some of the control needed to govern DNS usage within their networks unless they allow only their chosen DoH resolver to be used. Enterprise DNS controls can prevent numerous threat techniques used by cyber threat actors for initial access, command and control, and exfiltration. Using DoH with external resolvers can be good for home or mobile users and networks that do not use DNS security controls. For enterprise networks, however, NSA recommends using only designated enterprise DNS resolvers in order to properly leverage essential enterprise cybersecurity defenses, facilitate access to local network resources, and protect internal network information. The enterprise DNS resolver may be either an enterprise-operated DNS server or an externally hosted service. Either way, the enterprise resolver should support encrypted DNS requests, such as DoH, for local privacy and integrity protections, but all other encrypted DNS resolvers should be disabled and blocked.
    [Show full text]
  • Chapter 2. Application Layer Table of Contents 1. Context
    Chapter 2. Application Layer Table of Contents 1. Context ........................................................................................................................................... 1 2. Introduction .................................................................................................................................... 2 3. Objectives ....................................................................................................................................... 2 4. Network application software ....................................................................................................... 2 5. Process communication ................................................................................................................. 3 6. Transport Layer services provided by the Internet ....................................................................... 3 7. Application Layer Protocols ........................................................................................................... 4 8. The web and HTTP .......................................................................................................................... 4 8.1. Web Terminology ................................................................................................................... 5 8.2. Overview of HTTP protocol .................................................................................................... 6 8.3. HTTP message format ...........................................................................................................
    [Show full text]
  • Analysis of Malware and Domain Name System Traffic
    Analysis of Malware and Domain Name System Traffic Hamad Mohammed Binsalleeh A Thesis in The Department of Computer Science and Software Engineering Presented in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy at Concordia University Montréal, Québec, Canada July 2014 c Hamad Mohammed Binsalleeh, 2014 CONCORDIA UNIVERSITY Division of Graduate Studies This is to certify that the thesis prepared By: Hamad Mohammed Binsalleeh Entitled: Analysis of Malware and Domain Name System Traffic and submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy complies with the regulations of this University and meets the accepted standards with respect to originality and quality. Signed by the final examining committee: Chair Dr. Christian Moreau External Examiner Dr. Nadia Tawbi Examiner to Program Dr. Lingyu Wang Examiner Dr. Peter Grogono Examiner Dr. Olga Ormandjieva Thesis Co-Supervisor Dr. Mourad Debbabi Thesis Co-Supervisor Dr. Amr Youssef Approved by Chair of the CSE Department 2014 Dean of Engineering ABSTRACT Analysis of Malware and Domain Name System Traffic Hamad Mohammed Binsalleeh Concordia University, 2014 Malicious domains host Command and Control servers that are used to instruct in- fected machines to perpetuate malicious activities such as sending spam, stealing creden- tials, and launching denial of service attacks. Both static and dynamic analysis of malware as well as monitoring Domain Name System (DNS) traffic provide valuable insight into such malicious activities and help security experts detect and protect against many cyber attacks. Advanced crimeware toolkits were responsible for many recent cyber attacks. In order to understand the inner workings of such toolkits, we present a detailed reverse en- gineering analysis of the Zeus crimeware toolkit to unveil its underlying architecture and enable its mitigation.
    [Show full text]
  • Internet Domain Name System
    IINNTTEERRNNEETT DDOOMMAAIINN NNAAMMEE SSYYSSTTEEMM http://www.tutorialspoint.com/internet_technologies/internet_domain_name_system.htm Copyright © tutorialspoint.com Overview When DNS was not into existence, one had to download a Host file containing host names and their corresponding IP address. But with increase in number of hosts of internet, the size of host file also increased. This resulted in increased traffic on downloading this file. To solve this problem the DNS system was introduced. Domain Name System helps to resolve the host name to an address. It uses a hierarchical naming scheme and distributed database of IP addresses and associated names IP Address IP address is a unique logical address assigned to a machine over the network. An IP address exhibits the following properties: IP address is the unique address assigned to each host present on Internet. IP address is 32 bits 4bytes long. IP address consists of two components: network component and host component. Each of the 4 bytes is represented by a number from 0 to 255, separated with dots. For example 137.170.4.124 IP address is 32-bit number while on the other hand domain names are easy to remember names. For example, when we enter an email address we always enter a symbolic string such as [email protected]. Uniform Resource Locator URL Uniform Resource Locator URL refers to a web address which uniquely identifies a document over the internet. This document can be a web page, image, audio, video or anything else present on the web. For example, www.tutorialspoint.com/internet_technology/index.html is an URL to the index.html which is stored on tutorialspoint web server under internet_technology directory.
    [Show full text]
  • Secure Shell- Its Significance in Networking (Ssh)
    International Journal of Application or Innovation in Engineering & Management (IJAIEM) Web Site: www.ijaiem.org Email: [email protected] Volume 4, Issue 3, March 2015 ISSN 2319 - 4847 SECURE SHELL- ITS SIGNIFICANCE IN NETWORKING (SSH) ANOOSHA GARIMELLA , D.RAKESH KUMAR 1. B. TECH, COMPUTER SCIENCE AND ENGINEERING Student, 3rd year-2nd Semester GITAM UNIVERSITY Visakhapatnam, Andhra Pradesh India 2.Assistant Professor Computer Science and Engineering GITAM UNIVERSITY Visakhapatnam, Andhra Pradesh India ABSTRACT This paper is focused on the evolution of SSH, the need for SSH, working of SSH, its major components and features of SSH. As the number of users over the Internet is increasing, there is a greater threat of your data being vulnerable. Secure Shell (SSH) Protocol provides a secure method for remote login and other secure network services over an insecure network. The SSH protocol has been designed to support many features along with proper security. This architecture with the help of its inbuilt layers which are independent of each other provides user authentication, integrity, and confidentiality, connection- oriented end to end delivery, multiplexes encrypted tunnel into several logical channels, provides datagram delivery across multiple networks and may optionally provide compression. Here, we have also described in detail what every layer of the architecture does along with the connection establishment. Some of the threats which Ssh can encounter, applications, advantages and disadvantages have also been mentioned in this document. Keywords: SSH, Cryptography, Port Forwarding, Secure SSH Tunnel, Key Exchange, IP spoofing, Connection- Hijacking. 1. INTRODUCTION SSH Secure Shell was first created in 1995 by Tatu Ylonen with the release of version 1.0 of SSH Secure Shell and the Internet Draft “The SSH Secure Shell Remote Login Protocol”.
    [Show full text]
  • A Diversified Set of Security Features for XMPP Communication Systems
    International Journal on Advances in Security, vol 6 no 3 & 4, year 2013, http://www.iariajournals.org/security/ 99 A Diversified Set of Security Features for XMPP Communication Systems Useful in Cloud Computing Federation Antonio Celesti, Massimo Villari, and Antonio Puliafito DICIEAMA, University of Messina Contrada di Dio, S. Agata, 98166 Messina, Italy. e-mail: facelesti, mvillari, apuliafi[email protected] Abstract—Nowadays, in the panorama of Cloud Computing, Presence Protocol (XMPP), i.e., an open-standard commu- finding a right compromise between interactivity and security nications protocol for message-oriented middleware based is not trivial at all. Currently, most of Cloud providers base on the XML (Extensible Markup Language). On one hand, their communication systems on the web service technology. The problem is that both Cloud architectures and services the XMPP is able to overcome the disadvantages of web have started as simple but they are becoming increasingly services in terms of performance, but on the other hand complex. Consequently, web services are often inappropriate. it lacks of native security features for addressing the new Recently, many operators in both academia and industry are emerging Cloud computing scenarios. evaluating the eXtensible Messaging and Presence Protocol for In this paper, we discuss how the XMPP can be adopted the implementation of Cloud communication systems. In fact, the XMPP offers many advantages in term of real-time capa- for the development of secure Cloud communication sys- bilities, efficient data distribution, service discovery, and inter- tems. In particular, we combine and generalize the assump- domain communication compared to web service technologies. tions made in our previous works respectively regarding how Nevertheless, the protocol lacks of native security features.
    [Show full text]
  • Domain Name System System Work?
    What is the DNS? - how it works Isaac Maposa | Dev Anand Teelucksingh | Beran Gillen Community Onboarding Program | 11 March 2017 Agenda 1 2 3 What is the Domain Structure of the How does the Name System? Domain Name Domain Name System System Work? 4 5 6 Who makes the Stakeholders in the Engage with ICANN Domain Name Domain Name ??? System Work? System. | 2 What is the Domain Name System (DNS)? The Internet, what is it..? ● The Internet is a network of networks that interconnects devices to exchange information. ● In order to “talk” to each other, all of these devices must have a unique numerical address called an Internet Protocol address or IP Address. An example of an IP address is 94.127.53.132 ● When you visit a website from your browser, you are requesting the website from your device’s IP address to the web server’s IP address. ● However, you don’t type in the ip address of the web server, rather the domain name of for example www.google.com ● In so doing, you have queried the DNS. ● So what is this DNS???? | 4 What is the Domain Name System? ● The Domain Name System or DNS overcomes this problem of remembering IP addresses by mapping domain names to IP addresses. ● While this sounds like a phone book, it is not a centralised database. ● The DNS is a distributed database across a hierarchy of networks of servers and provide ways for devices and software (like browsers and email) to query the DNS to get an IP address. ● Domain names must be unique.
    [Show full text]
  • Iot Communications a 5G Smart Cities Case Study Approach
    1 End to End VANET/ IoT Communications A 5G Smart Cities Case Study Approach Melvin Hayes1 and Tamer Omar2 Department of Technology Management, Indiana State University Terre Haute 1 Department of Electrical and Computer Engineering, Cal-Poly Pomona 2 Email: [email protected], [email protected] Abstract—This paper investigates the infrastructure to vehi- in achieving end-to-end communications for IoT datum and cle and infrastructure to cloud connectivity and reliability in meta-data collection and dissemination platform for IoV. the vehicular ad hoc networks (VANET) area of Intelligent Transportation Systems (ITS). A key focus of this work is to Furthermore, this work highlights and investigates the role investigate protocols that will enhance real-time, robust and that Zero-Configuration a set of technologies that can auto- reliable communication methods, and complement autonomous vehicles’ navigation experiences within smart cities. The main matically creates a usable RSUs network based on the Internet areas of study include highway infrastructure that include the Protocol Suite to support the proposed end to end communi- Wireless Sensor Networks (WSN) to the Cloud (web service) and cations systems design. This work is predominately interested vice-versa. The pertinent cloud-based data will be communicated in the upper layers of the data communication protocols for to subscribed vehicles (with password access) to complete the the Internet of Things (IoT) harmonization of WSN devices V2I and I2V communication cycle. The data collected from the WSN is communicated to the cloud via XML over XMPP, that can be used for a Vehicular Ad-Hoc Network (VANET) zero configuration, and mDNS protocols.
    [Show full text]
  • Electronic Mail
    Electronic Mail • The protocols used for Internet email can be divided into three broad categories transfer program interface application interface application 33 The Simple Mail Transfer Protocol (()SMTP) • The Simple Mail Transfer Protocol (SMTP) is the standard protocol that a mail transfer program uses • SMTP can be characterized as: – Follows a stream paradigm – Uses textual control messages – Only transfers text messages – Allows a sender to specify recipients’ names and check each name • SMTP can sen d a s ing le message to mu ltilltiple rec iiipien ts – The protocol allows a client to list users and then send a single copy of a message for all users on the list • SMTP has a restriction to send only textual content – MIME standard that allows email to include attachments such as graphic images or binary files – MIME: Multipurpose Internet Mail Extension 34 Response of the server with a code Establishing a session! linefeed and Carriage Return John (on example.edu) is sending an email to Math and Paul on somewhere.com 35 linefeed and Carriage Return Other commands 36 ISPs, Mail Servers, and Mail Access • ISPs began offer email services – An ISP runs an email server and provides a mailbox for each user • each ISP provides interface that allows a user to access their mailbox • Email access follows one of two forms: – A special-purpose email interface application (OUTLOOK) –A web browser that accesses an email web page 37 ISPs, Mail Servers, and Mail Access • The web browser approach is straightforward: – an ISP provides a special
    [Show full text]
  • Federal Register/Vol. 80, No. 193/Tuesday, October 6, 2015
    Federal Register / Vol. 80, No. 193 / Tuesday, October 6, 2015 / Notices 60363 identification card for access to federal and capabilities, but no earlier than Based Security for Electronic Mail facilities if such license or identification November 5, 2015. When the building Building Block. The full building block card is issued by a state that is block has been completed, NIST will description can be viewed at: http:// compliant with the REAL ID Act of 2005 post a notice on the Domain Name nccoe.nist.gov/DNSSecuredEmail. (P.L. 109–13), or by a state that has an System-Based Security for Electronic Interested parties should contact NIST extension for REAL ID compliance. Mail Building Block Web site at using the information provided in the NIST currently accepts other forms of http://nccoe.nist.gov/DNSSecuredEmail FOR FURTHER INFORMATION CONTACT federal-issued identification in lieu of a announcing the completion of the section of this notice. NIST will then state-issued driver’s license. For building block and informing the public provide each interested party with a detailed information please contact Ms. that it will no longer accept letters of letter of interest template, which the Young or visit: http://www.nist.gov/ interest for this building block. party must complete, certify that it is public_affairs/visitor/. ADDRESSES: The NCCoE is located at accurate, and submit to NIST and which 9600 Gudelsky Drive, Rockville, MD identifies the organization requesting Richard Cavanagh, 20850. Letters of interest must be participation in the Domain Name Acting Associate Director for Laboratory submitted to [email protected] System-Based Security for Electronic Programs.
    [Show full text]
  • M-Link Administration Guide M-Link Administration Guide Ii
    MLINKADM-17.0 M-Link Administration Guide M-Link Administration Guide ii Table of Contents Chapter 1 Isode M-Link Overview............................................................................................. 1 This chapter gives an overview of Isode M-Link. Chapter 2 M-Link: Getting Started........................................................................................... 4 This chapter discusses M-Link Server creation. Chapter 3 Domains.................................................................................................................... 47 This chapter describes how M-Link Console can be used to view, modify, create and delete domains. Chapter 4 Con®guring Groups................................................................................................. 52 This chapter discusses how M-Link Console can be used to view, modify, create and delete groups for an M-Link service. Chapter 5 Con®guring TLS...................................................................................................... 54 This chapter discusses how to manage TLS con®guration of an M-Link service. Chapter 6 M-Link User Management...................................................................................... 68 This chapter discusses provisioning of user, user authentication and authorization, and groups. Chapter 7 Security Labels in XMPP........................................................................................ 90 This chapter discusses M-Link con®guration of security labels. Chapter 8 M-Link Edge, Peers
    [Show full text]