Tag Archives: protocols

SPDY: Google wants to speed up the web by ditching HTTP

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In an attempt to avoid these issues, SPDY uses a single SSL-encrypted session between a browser and a client, and then compresses all the request/response overhead. The requests, responses, and data are all put into frames that are multiplexed over the one connection. This makes it possible to send a higher-priority small file without waiting for the transfer of a large file that’s already in progress to terminate.

via SPDY: Google wants to speed up the web by ditching HTTP.

This article is two years old.

Google works on Internet standards with TCP proposals, SPDY standardization

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Google’s focus is on reducing latency between client machines and servers, and in particular, reducing the number of round trips (either client to server and back to client, or vice versa) required. When data is sent over a TCP connection, its receipt must be acknowledged by the receiving end. The sending end can only send a certain number of packets before it must wait for an acknowledgement. The time taken to receive an acknowledged is governed by the round-trip time (RTT). With high bandwidth, high latency connections, clients and servers can end up spending most of their time waiting for acknowledgements, rather than sending packets.

via Google works on Internet standards with TCP proposals, SPDY standardization.

More far-reaching than these SSL tweaks is Google’s proposed alternative to the HTTP protocol that underpins the Web: SPDY.

TCP may keep its offered receive window closed indefinitely RFC 1122

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Part of the Transmission Control Protocol TCP specification RFC 1122 allows a receiver to advertise a zero byte window, instructing the sender to maintain the connection but not send additional TCP payload data. The sender should then probe the receiver to check if the receiver is ready to accept data. Narrow interpretation of this part of the specification can create a denial-of-service vulnerability. By advertising a zero receive window and acknowledging probes, a malicious receiver can cause a sender to consume resources TCP state, buffers, and application memory, preventing the targeted service or system from handling legitimate connections.

via US-CERT Vulnerability Note VU#723308 – TCP may keep its offered receive window closed indefinitely RFC 1122.

NetBIOS/NBNS

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NBNS serves much the same purpose as DNS does: translate human-readable names to IP addresses e.g. www.wireshark.org to 65.208.228.223. As NetBIOS can run on top of several different network protocols e.g. IP, IPX, …, other implementations of the NetBIOS services have their own mechanisms for translating NetBIOS names to addresses. NBNS’s services are more limited, in that NetBIOS names exist in a flat name space, rather than DNS’s hierarchical one multiple flat name spaces can exist, by using NetBIOS scopes, but those are rarely used, and NBNS can only supply IPv4 addresses; NBNS doesn’t support IPv6.

via NetBIOS/NBNS – The Wireshark Wiki.

The TCP Datagram

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push flag (1 bits)

The push flag tells the receiving end of the tcp connection to “push” all buffered data to the receiving application. It basically says “done for now”.

via The TCP Datagram.

This would be the PSH flag that I needed to look up and found this site which makes for a good reference.

Daytime Protocol

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Daytime Protocol – Wikipedia, the free encyclopedia.

The Daytime Protocol is a service in the Internet Protocol Suite, defined in 1983 in RFC 867. It is intended for testing and measurement purposes in computer networks.

A host may connect to a server that supports the Daytime Protocol on either Transmission Control Protocol (TCP) or User Datagram Protocol (UDP) port 13. The server returns an ASCII character string of the current date and time in an unspecified format.

Apparently some HTC devices use this protocol.

Fibre Channel

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Fibre Channel Protocol (FCP) is a transport protocol (similar to TCP used in IP networks) which predominantly transports SCSI commands over Fibre Channel networks.[1][2]

via Fibre Channel – Wikipedia, the free encyclopedia.

Despite its name, Fibre Channel signaling can run on both twisted paircopperwire and fiber-opticcables.[1][2]

I still need to know how this is done over fibre.