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../../protocols/ssh.rst:85
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encryption
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../../protocols/tcp.rst:26
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To provide this service, TCP relies on a simple segment format that is shown in the figure below. Each TCP segment contains a header described below and, optionally, a payload. The default length of the TCP header is twenty bytes, but some TCP headers contain options.
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../../protocols/tls.rst:43
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../../protocols/transport-service.rst:22
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`IP version 4` addresses that are 32 bits wide
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../../protocols/udp.rst:51
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The UDP header contains four fields :
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../../protocols/wifi.rst:19
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Range (m) indoor/outdoor
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../../bibliography.rst:36
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Buford, J., Yu, H., Lua, E.K., `P2P Networking and Applications <http://books.google.com/books?id=O9NkAaY9YxMC>`_, Morgan Kaufmann, 2008
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../../index.rst:163
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:ref:`genindex`
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../../glossary.rst:270
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The Address Resolution Protocol is a protocol used by IPv4 devices to obtain the datalink layer address that corresponds to an IPv4 address on the local area network. ARP is defined in :rfc:`826`
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../../exercises/ex-sharing.rst:203
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In practice, hosts transmit variable length frames. Consider a cable having a bandwidth of 100 Mbps and a length of 2 kilometers.
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../../exercises/reliability.rst:30
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Derive a mathematical expression that provides the `goodput`, i.e. the amount of payload bytes that have been transmitted during a period of time, achieved by the Alternating Bit Protocol assuming that :
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../../exercises/network.rst:97
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the router located in `Washington` ?
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../../exercises/transport.rst:88
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Consider a transport protocol that provides a reliable connection-oriented bytestream service. You observe the segments sent by a host that uses this protocol. Does the time-sequence diagram below reflects a valid implementation of this protocol ? Justify your answer.
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../../principles/naming.rst:59
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BNF of the fully qualified host names
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../../principles/referencemodels.rst:39
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the Physical layer may deliver `more` bits to the receiver than the bits sent by the sender
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../../principles/network.rst:66
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This network contains two types of devices. The hosts, represented with circles and the routers, represented as boxes. A host is a device which is able to send and receive data for its own usage in contrast with routers that most of the time simply forward data towards their final destination. Routers have multiple links to neighboring routers or hosts. Hosts are usually attached via a single link to the network. Nowadays, with the growth of wireless networks, more and more hosts are equipped with several physical interfaces. These hosts are often called `multihomed`. Still, using several interfaces at the same time often leads to practical issues that are beyond the scope of this document. For this reason, we only consider `single-homed` hosts in this e-book.
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../../principles/transport.rst:31
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Alice : `What time is it ?`
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../../principles/sharing.rst:45
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A fourth physical organization of a network is the ring topology. Like the bus organization, each host has a single physical interface connecting it to the ring. Any signal sent by a host on the ring will be received by all hosts attached to the ring. From a redundancy point of view, a single ring is not the best solution, as the signal only travels in one direction on the ring; thus if one of the links composing the ring is cut, the entire network fails. In practice, such rings have been used in local area networks, but are now often replaced by star-shaped networks. In metropolitan networks, rings are often used to interconnect multiple locations. In this case, two parallel links, composed of different cables, are often used for redundancy. With such a dual ring, when one ring fails all the traffic can be quickly switched to the other ring.
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../../protocols/dns.rst:42
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The last four sections of the DNS message contain `Resource Records` (RR). All RRs have the same top level format shown in the figure below.
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../../principles/security.rst:134
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In the previous example, we have explained how Eve could capture data from a particular user. This is not the only attack of this type. In 2013, based on documents collected by Edward Snowden, the press revealed that several governmental agencies were collecting lots of data on various links that compose the global Internet [Greenwald2014]_. Thanks to this massive amount of data, these governmental agencies have been able to extract lots of information about the behavior of Internet users. Like Eve, they are in a position to extract passwords, usernames and other privacy sensitive data from all the packets that they have captured. However, it seems that these agencies were often more interested in various meta data, e.g. information showing with whom a given user communicates than the actual data exchanged. These revelations have shocked the Internet community and the `Internet Engineering Task Force <https://www.ietf.org>`_ that manages the standardization of Internet protocols has declared in :rfc:`7258` that such pervasive monitoring is an attack that need to be countered in the development of new protocols. Several new protocols and extensions to existing ones are being developed to counter these attacks.
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