Exit Zen
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../../exercises/ex-sharing.rst:11
English
Sharing resources
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../../exercises/reliability.rst:11
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Open questions
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../../exercises/transport.rst:10
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This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=3 or help us by providing pull requests to close the existing issues.
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../../principles/naming.rst:9
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The network and the transport layers rely on addresses that are encoded as fixed size bit strings. A network layer address uniquely identifies a host. Several transport layer entities can use the service of the same network layer. For example, a reliable transport protocol and a connectionless transport protocol can coexist on the same host. In this case, the network layer multiplexes the segments produced by these two protocols. This multiplexing is usually achieved by placing in the network packet header a field that indicates which transport protocol should process the segment. Given that there are few different transport protocols, this field does not need to be long. The port numbers play a similar role in the transport layer since they enable it to multiplex data from several application processes.
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../../principles/referencemodels.rst:12
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The reference models
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../../principles/network.rst:10
English
This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=2 or help us by providing pull requests to close the existing issues.
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../../principles/reliability.rst:14
English
This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=1 or help us by providing pull requests to close the existing issues.
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../../principles/transport.rst:10
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Applications
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../../principles/sharing.rst:14
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Sharing resources
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../../principles/security.rst:10
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In the early days, data networks were mainly used by researchers and security was not a concern. A few users were connected and capable of using the network. Almost all the devices attached to the network were openly accessible and users were trusted. As the utilization of the networks grew, security concerns started to appear. In universities, researchers and professors did not always trust their students and required some forms of access control. On standalone computers, the common access control mechanism is the password. A `username` is assigned to each user and when this user wants to access the computer, he or she needs to provide his/her `username` and his/her `password`. Most passwords are composed of a sequence of characters. The strength of the password is function of the difficulty of guessing the characters chosen by each user. Various guidelines have been defined on how to select a good password [#fpasswords]_. Some systems require regular modifications of the passwords chosen by their users.
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../../exercises/dns.rst:11
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This is an unpolished draft of the third edition of this e-book. If you find any error or have suggestions to improve the text, please create an issue via https://github.com/CNP3/ebook/issues?milestone=5 or help us by providing pull requests to close the existing issues.
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../../exercises/email.rst:7
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Many Internet protocols are ASCII_-based protocols where the client sends requests as one line of ASCII_ text terminated by `CRLF` and the server replies with one of more lines of ASCII_ text. Using such ASCII_ messages has several advantages compared to protocols that rely on binary encoded messages
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../../exercises/http.rst:8
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An important difference between HTTP/1.0, HTTP/1.1 and HTTP/2.0 is their utilization of the underlying transport connections. Answer the three questions below to confirm that you understand the difference between these versions of the HTTP protocol.
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../../exercises/ipv6.rst:9
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Basic questions on IPv6 Networks
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../../exercises/lan.rst:18
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Exercises
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../../exercises/routing-policies.rst:9
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Exercises
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../../exercises/routing-protocols.rst:9
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Routing protocols play a key role in the Internet since they ensure that all the routers have valid routing tables. In this section, we use IPMininet_ to explore how intradomain and interdomain routing protocols work in practice. IPMininet_ adds an abstraction layer above the actual configuration of the FRRouting daemons that implement these routing protocols.
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../../exercises/tcp-2.rst:10
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In this series of exercises, you will explore in more details the operation of TCP and its congestion control scheme. TCP is a very important protocol in today's Internet since most applications use it to exchange data. We first look at TCP in more details by injecting segments in the Linux TCP stack and analyze how the stack reacts. Then we study the TCP congestion control scheme.
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../../exercises/tcp.rst:9
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TCP is one of the key protocols in today's Internet. A TCP connection always starts with a three-way handshake. The exercises below should help you to improve your understandings of this first phase of a TCP connection.
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../../exercises/tls.rst:8
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One of the first motivations for the deployment of wide area networks such as the Internet was to enable researchers to connect to distant servers. For many years, these connections were carried out by using a simple application layer protocol such as telnet over a TCP connection. With telnet, all the characters typed by the user are sent in cleartext over the TCP connection. This implies that if someone is able to capture the packets transmitted over the network, he/she can collect sensitive information such as user names or passwords.
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