Exit Zen
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../../protocols/routing.rst:19
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These intradomain routing protocols usually have two objectives. First, they distribute routing information that corresponds to the shortest path between two routers in the domain. Second, they should allow the routers to quickly recover from link and router failures.
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../../protocols/rpc.rst:13
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The caller transfers the control of execution to the callee's procedure
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../../protocols/ssh.rst:46
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The secure shell protocol was designed in the mid 1990s by T. Ylonen to counter the eavesdropping attacks against :term:`telnet` and similar protocols [Ylonen1996]_. :term:`ssh` became quickly popular and system administrators encouraged its usage. The original version of :term:`ssh` was freely available. After a few years, his author created a company to distribute it commercially, but other programmers continued to develop an open-source version of :term:`ssh` called `OpenSSH <http://www.openssh.com>`_. Over the years, :term:`ssh` evolved and became a flexible applicable whose usage extends beyond remote login to support features such as file transfers, protocol tunneling, ... In this section, we only discuss the basic features of :term:`ssh` and explain how it differs from :term:`telnet`. Entire books have been written to describe :term:`ssh` in details [BS2005]_. An overview of the protocol appeared in [Stallings2009]_.
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../../protocols/tcp.rst:17
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World wide web ( :term:`HTTP`, ...)
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../../protocols/tls.rst:30
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A TLS session can be initiated in two different ways. First, the application can use a dedicated TCP port number for application layer protocol x-over-TLS. This is the solution used by many HTTP servers that reserve port :math:`443` for HTTP over TLS. This solution works, but it requires to reserve two ports for each application : one where the application-layer protocol is used directly over TCP and another one where the application-layer protocol is used over TLS. Given the limited number of TCP ports that are available, this is not a scalable solution. The table below provides some of the reserved port numbers for application layer protocols on top of TLS.
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../../protocols/transport-service.rst:13
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The connectionless service allows applications to easily exchange messages or Service Data Units. On the Internet, this service is provided by the UDP protocol that will be explained in the next chapter. The connectionless transport service on the Internet is unreliable, but is able to detect transmission errors. This implies that an application will not receive data that has been corrupted due to transmission errors.
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../../protocols/udp.rst:15
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the UDP service will not deliver a corrupted SDU to the destination
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../../protocols/wifi.rst:15
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Today, WiFi is a very popular wireless networking technology. There are more than several hundreds of millions of WiFi devices. The development of this technology started in the late 1980s with the `WaveLAN <http://en.wikipedia.org/wiki/WaveLAN>`_ proprietary wireless network. WaveLAN operated at 2 Mbps and used different frequency bands in different regions of the world. In the early 1990s, the IEEE_ created the `802.11 working group <http://www.ieee802.org/11/>`_ to standardize a family of wireless network technologies. This working group was very prolific and produced several wireless networking standards that use different frequency ranges and different physical layers. The table below provides a summary of the main 802.11 standards.
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../../bibliography.rst:17
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Androutsellis-Theotokis, S. and Spinellis, D.. .. 2004. `A survey of peer-to-peer content distribution technologies <http://doi.acm.org/10.1145/1041680.1041681>`_. ACM Computing Surveys 36, 4 (December 2004), 335-371.
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../../exercises/ex-sharing.rst:66
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In a shared medium, a collision may happen if two hosts transmit at almost the same time as shown in the example below.
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../../principles/security.rst:62
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Threats
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../../exercises/dns.rst:27
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A typical usage of dig is as follows:
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../../exercises/email.rst:13
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Telnet is a protocol that allows to obtain a terminal on a remote server. For this, telnet opens a TCP connection with the remote server on port 23. However, most `telnet` implementations allow the user to specify an alternate port as `telnet hosts port` When used with a port number as parameter, `telnet` opens a TCP connection to the remote host on the specified port. `telnet` can thus be used to test any server using an ASCII-based protocol on top of TCP. Note that if you need to stop a running `telnet` session, ``Ctrl-C`` will not work as it will be sent by `telnet` to the remote host over the TCP connection. On many `telnet` implementations you can type ``Ctrl-]`` to freeze the TCP connection and return to the telnet interface.
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../../exercises/http.rst:22
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Can you explain the different headers placed by curl_ in the request ?
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../../exercises/ipv6.rst:31
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Design questions
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../../exercises/lan.rst:31
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Consider the switched network shown in the figure below. Compute the Spanning Tree of this network.
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../../exercises/routing-policies.rst:59
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from `AS4` to `AS2`
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../../exercises/routing-protocols.rst:83
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We use this mininet_ topology to collect packet traces that show the packets that OSPF routers exchange. For this, we add the following ``post_build`` method that IPMininet_ starts after having constructed the network and before launching the daemons. It simply starts tcpdump_ on each router to collect the first 100 OSPF packets that they send/receive.
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../../exercises/tcp-2.rst:20
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Let us start with a very simple example that uses packetdrill_ to open a TCP connection on a server running on the Linux kernel. A packetdrill_ script is a sequence of lines that are executed one after the other. There are three main types of lines in a packetdrill_ script.
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../../exercises/tcp.rst:52
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With your knowledge of TCP, you should now be able to reorder all the segments exchanged over a TCP connection.
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