Exit Zen
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../../protocols/http.rst:164
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the `Server:` header indicates the version of the web server that has generated the HTTP response. Some servers provide information about their software release and optional modules that they use. For security reasons, some system administrators disable these headers to avoid revealing too much information about their server to potential attackers.
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../../protocols/ipv6.rst:156
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A `subnet identifier` that identifies a customer of the ISP
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../../protocols/ethernet.rst:169
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Comments
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../../protocols/routing.rst:139
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How to quickly detect a link failure ?
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../../protocols/tcp.rst:129
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At this point, the TCP connection is open and both the client and the server are allowed to send TCP segments containing data. This is illustrated in the figure below.
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../../protocols/tls.rst:190
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The server replies to the ``ClientHello`` with several messages:
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../../protocols/wifi.rst:107
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When a frame is sent from a WiFi device to a server attached to the same LAN as the access point, the first address of the frame is set to the MAC address of the access point, the second address is set to the MAC address of the source WiFi device and the third address is the address of the final destination on the LAN. When the server replies, it sends an Ethernet frame whose source address is its MAC address and the destination address is the MAC address of the WiFi device. This frame is captured by the access point that converts the Ethernet header into an 802.11 frame header. The 802.11 frame sent by the access point contains three addresses : the first address is the MAC address of the destination WiFi device, the second address is the MAC address of the access point and the third address the MAC address of the server that sent the frame.
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../../bibliography.rst:133
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Mills, D.L., `Computer Network Time Synchronization: the Network Time Protocol <http://books.google.com/books?id=pdTcJBfnbq8C>`_. CRC Press, March 2006, 304 pp.
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../../glossary.rst:321
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A service that enables a user to send or receive a file from a distant server over the network. The File Transfer Protocol :term:`FTP` was a popular service. It has now been replaced by HTTP/HTTPs or more secure protocols such as the `SSH File Transfer Protocol <https://en.wikipedia.org/wiki/SSH_File_Transfer_Protocol>`_.
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../../principles/network.rst:151
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In a tree-shaped network, it is relatively simple for each node to automatically compute its forwarding table by inspecting the packets that it receives. For this, each node uses the source and destination addresses present inside each packet. Thanks to the source address, a node can learn the location of the different sources inside the network. Each source has a unique address. When a node receives a packet over a given interface, it learns that the source (address) of this packet is reachable via this interface. The node maintains a data structure that maps each known source address to an incoming interface. This data structure is often called the `port-address table` since it indicates the interface (or port) to reach a given address.
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../../principles/transport.rst:91
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The first possibility was named `big-endian` in a note written by Cohen [Cohen1980]_ while the second was named `little-endian`. Vendors of CPUs that used `big-endian` in memory insisted on using `big-endian` encoding in networked applications while vendors of CPUs that used `little-endian` recommended the opposite. Several studies were written on the relative merits of each type of encoding, but the discussion became almost a religious issue [Cohen1980]_. Eventually, the Internet chose the `big-endian` encoding, i.e. multi-byte fields are always transmitted by sending the most significant byte first, :rfc:`791` refers to this encoding as the :term:`network-byte order`. Most libraries [#fhtonl]_ used to write networked applications contain functions to convert multi-byte fields from memory to the network byte order and the reverse.
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../../principles/sharing.rst:185
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By combining different answers to these questions, network researchers have developed different packet discard mechanisms.
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../../principles/security.rst:433
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To efficiently sign messages, Alice needs to be able to compute a summary of her message in a way that makes prohibits an attacker from generating a different message that has the same summary. `Cryptographic hash functions` were designed to solve this problem. The ideal hash function is a function that returns a different number for every possible input. In practice, it is impossible to find such a function. Cryptographic hash functions are an approximation of this perfect summarization function. They compute a summary of a given message in 128, 160, 256 bits or more. They also exhibit the `avalanche effect`. This effect indicates that a small change in the message causes a large change in the hash value. Finally hash functions are very difficult to invert. Knowing a hash value, it is computationally very difficult to find the corresponding input message. Several hash functions have been proposed by cryptographers. The most popular ones are :
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../../exercises/ipv6.rst:471
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In this network, we will focus on four IPv6 prefixes :
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../../exercises/routing-protocols.rst:518
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If you launch the script and immediately type ``ping6all`` to check the connectivity, you might obtained the following result.
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../../exercises/tcp-2.rst:637
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Open questions
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../../protocols/bgp.rst:132
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a list of IP prefixes that are (re-)advertised
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../../protocols/congestion.rst:212
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TCP connections that use a large MSS can achieve a higher throughput that the TCP connections that use a shorter MSS. This creates another source of unfairness between TCP connections. However, it should be noted that today most hosts are using almost the same MSS, roughly 1460 bytes.
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../../protocols/email.rst:215
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`video`. The message part contains a video clip. The subtype indicates the format of the video clip like `avi <http://en.wikipedia.org/wiki/Audio_Video_Interleave>`_ or `mp4 <http://en.wikipedia.org/wiki/Mp4>`_.
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../../protocols/ethernet.rst:178
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Two multi-mode or single mode optical fibers with lasers
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