Much of this content is based on http://en.cship.org/wiki/Special:Allpages
An aggregator is a service that gathers syndicated information from one or many sites and makes it available at a different address. Sometimes called an RSS aggregator, a feed aggregator, a feed reader, or a news reader. (Not to be confused with a Usenet News reader.)
(Not be confused with privacy, pseudonymity, security, or confidentiality.)
Anonymity on the Internet is the ability to use services without leaving clues to one's identity. The level of protection depends on the anonymity techniques used and the extent of monitoring. The strongest techniques in use to protect anonymity involve creating a chain of communication using a random process to select some of the links, in which each link has access to only partial information about the process. The first knows the user's IP address but not the content, destination, or purpose of the communication, because the message contents and destination information are encrypted. The last knows the identity of the site being contacted, but not the source of the session. One or more steps in between prevents the first and last links from sharing their partial knowledge in order to connect the user and the target site.
An anonymous remailer is a service that accepts e-mail messages containing instructions for delivery, and sends them out without revealing their sources. Since the remailer has access to the user's address, the content of the message, and the destination of the message, remailers should be used as part of a chain of multiple remailers so that no one remailer knows all this information.
ASP (application service provider)
An ASP is an organization that offers software services over the Internet, allowing the software to be upgraded and maintained centrally.
A backbone is one of the high-bandwidth communications links that tie together networks in different countries and organizations around the world to form the Internet.
The bandwidth of a connection is the maximum rate of data transfer on that connection, limited by its capacity and the capabilities of the computers at both ends of the connection.
bash (Bourne-again shell)
The bash shell is a command-line interface for Linux/Unix operating systems, based on the Bourne shell.
BitTorrent is a peer-to-peer file-sharing protocol invented by Bram Cohen in 2001. It allows individuals to cheaply and effectively distribute large files, such as CD images, video, or music files.
A blacklist is a list of forbidden persons or things. In Internet censorship, lists of forbidden Web sites may be used as blacklists; censorware may allow access to all sites except for those specifically listed on its blacklist. An alternative to a blacklist is a whitelist, or a list of permitted things. A whitelist system blocks access to all sites except for those specifically listed on the whitelist. This is a less common approach to Internet censorship. It is possible to combine both approaches, using string matching or other conditional techniques on URLs that do not match either list.
The blue URL bar (called the Bluebar in Psiphon lingo) is the form at the top of your Psiphon node browser window, which allows you to access blocked site by typing its URL inside.
See also Psiphon node
To block is to prevent access to an Internet resource, using any number of methods.
A bookmark is a placeholder within software that contains a reference to an external resource. In a browser, a bookmark is a reference to a Web page – by choosing the bookmark you can quickly load the Web site without needing to type in the full URL.
See Tor bridge.
A cache is a part of an information-processing system used to store recently used or frequently used data to speed up repeated access to it. A Web cache holds copies of Web page files.
To censor is to prevent publication or retrieval of information, or take action, legal or otherwise, against publishers and readers.
Censorware is software used to filter or block access to the Internet. This term is most often used to refer to Internet filtering or blocking software installed on the client machine (the PC which is used to access the Internet). Most such client-side censorware is used for parental control purposes.
Sometimes the term censorware is also used to refer to software used for the same purpose installed on a network server or router.
CGI (Common Gateway Interface)
CGI is a common standard used to let programs on a Web server run as Web applications. Many Web-based proxies use CGI and thus are also called "CGI proxies". (One popular CGI proxy application written by James Marshall using the Perl programming language is called CGIProxy.)
Chat, also called instant messaging, is a common method of communication among two or more people in which each line typed by a participant in a session is echoed to all of the others. There are numerous chat protocols, including those created by specific companies (AOL, Yahoo!, Microsoft, Google, and others) and publicly defined protocols. Some chat client software uses only one of these protocols, while others use a range of popular protocols.
Circumvention is publishing or accessing content in spite of attempts at censorship.
Common Gateway Interface
A method of controlling the execution of software using commands entered on a keyboard, such as a Unix shell or the Windows command line.
A cookie is a text string sent by a Web server to the user's browser to store on the user's computer, containing information needed to maintain continuity in sessions across multiple Web pages, or across multiple sessions. Some Web sites cannot be used without accepting and storing a cookie. Some people consider this an invasion of privacy or a security risk.
country code top-level domain (ccTLD)
Each country has a two-letter country code, and a TLD (top-level domain) based on it, such as .ca for Canada; this domain is called a country code top-level domain. Each such ccTLD has a DNS server that lists all second-level domains within the TLD. The Internet root servers point to all TLDs, and cache frequently-used information on lower-level domains.
DARPA (Defense Advanced Projects Research Agency)
DARPA is the successor to ARPA, which funded the Internet and its predecessor, the ARPAnet.
Decryption is recovering plain text or other messages from encrypted data with the use of a key.
See also encryption.
A domain can be a Top-Level Domain (TLD) or secondary domain on the Internet.
See also Top-Level Domain, country code Top-Level Domain and secondary domain.
DNS (Domain Name System)
The Domain Name System (DNS) converts domain names, made up of easy-to-remember combinations of letters, to IP addresses, which are hard-to-remember strings of numbers. Every computer on the Internet has a unique address (a little bit like an area code+telephone number).
A DNS leak occurs when a computer configured to use a proxy for its Internet connection nonetheless makes DNS queries without using the proxy, thus exposing the user's attempts to connect with blocked sites. Some Web browsers have configuration options to force the use of the proxy.
A DNS server, or name server, is a server that provides the look-up function of the Domain Name System. It does this either by accessing an existing cached record of the IP address of a specific domain, or by sending a request for information to another name server.
A DNS tunnel is a way to tunnel almost everything over DNS/Nameservers.
Because you "abuse" the DNS system for an unintended purpose, it only allows a very slow connection of about 3 kb/s which is even less than the speed of an analog modem. That is not enough for YouTube or file sharing, but should be sufficient for instant messengers like ICQ or MSN Messenger and also for plain text e-mail.
On the connection you want to use a DNS tunnel, you only need port 53 to be open; therefore it even works on many commercial Wi-Fi providers without the need to pay.
The main problem is that there are no public modified nameservers that you can use. You have to set up your own. You need a server with a permanent connection to the Internet running Linux. There you can install the free software OzymanDNS and in combination with SSH and a proxy like Squid you can use the tunnel. More Information on this on http://www.dnstunnel.de.
Eavesdropping is listening to voice traffic or reading or filtering data traffic on a telephone line or digital data connection, usually to detect or prevent illegal or unwanted activities or to control or monitor what people are talking about.
E-mail, short for electronic mail, is a method to send and receive messages over the Internet. It is possible to use a Web mail service or to send e-mails with the SMTP protocol and receive them with the POP3 protocol by using an e-mail client such as Outlook Express or Thunderbird. It is comparatively rare for a government to block e-mail, but e-mail surveillance is common. If e-mail is not encrypted, it could be read easily by a network operator or government.
An embedded script is a piece of software code.
Encryption is any method for recoding and scrambling data or transforming it mathematically to make it unreadable to a third party who doesn't know the secret key to decrypt it. It is possible to encrypt data on your local hard drive using software like TrueCrypt (http://www.truecrypt.org) or to encrypt Internet traffic with SSL or SSH.
See also decryption.
An exit node is a Tor node that forwards data outside the Tor network.
See also middleman node.
File sharing refers to any computer system where multiple people can use the same information, but often refers to making music, films or other materials available to others free of charge over the Internet.
file spreading engine
A file spreading engine is a Web site a publisher can use to get around censorship. A user only has to upload a file to publish once and the file spreading engine uploads that file to some set of sharehosting services (like Rapidshare or Megaupload).
To filter is to search in various ways for specific data patterns to block or permit communications.
Firefox is the most popular free and open source Web browser, developed by the Mozilla Foundation.
On a Web site, a forum is a place for discussion, where users can post messages and comment on previously posted messages. It is distinguished from a mailing list or a Usenet newsgroup by the persistence of the pages containing the message threads. Newsgroup and mailing list archives, in contrast, typically display messages one per page, with navigation pages listing only the headers of the messages in a thread.
A frame is a portion of a Web page with its own separate URL. For example, frames are frequently used to place a static menu next to a scrolling text window.
FTP (File Transfer Protocol)
The FTP protocol is used for file transfers. Many people use it mostly for downloads; it can also be used to upload Web pages and scripts to some Web servers. It normally uses ports 20 and 21, which are sometimes blocked. Some FTP servers listen to an uncommon port, which can evade port-based blocking.
A popular free and open source FTP client for Windows and Mac OS is FileZilla. There are also some Web-based FTP clients that you can use with a normal Web browser like Firefox.
A gateway is a node connecting two networks on the Internet. An important example is a national gateway that requires all incoming or outgoing traffic to go through it.
A honeypot is a site that pretends to offer a service in order to entice potential users to use it, and to capture information about them or their activities.
A hop is a link in a chain of packet transfers from one computer to another, or any computer along the route. The number of hops between computers can give a rough measure of the delay (latency) in communications between them. Each individual hop is also an entity that has the ability to eavesdrop on, block, or tamper with communications.
HTTP (Hypertext Transfer Protocol)
HTTP is the fundamental protocol of the World Wide Web, providing methods for requesting and serving Web pages, querying and generating answers to queries, and accessing a wide range of services.
HTTPS (Secure HTTP)
Secure HTTP is a protocol for secure communication using encrypted HTTP messages. Messages between client and server are encrypted in both directions, using keys generated when the connection is requested and exchanged securely. Source and destination IP addresses are in the headers of every packet, so HTTPS cannot hide the fact of the communication, just the contents of the data transmitted and received.
IANA (Internet Assigned Numbers Authority)
IANA is the organization responsible for technical work in managing the infrastructure of the Internet, including assigning blocks of IP addresses for top-level domains and licensing domain registrars for ccTLDs and for the generic TLDs, running the root name servers of the Internet, and other duties.
ICANN (Internet Corporation for Assigned Names and Numbers)
ICANN is a corporation created by the US Department of Commerce to manage the highest levels of the Internet. Its technical work is performed by IANA.
Instant Messaging (IM)
Instant messaging is either certain proprietary forms of chat using proprietary protocols, or chat in general. Common instant messaging clients include MSN Messenger, ICQ, AIM or Yahoo! Messenger.
See man in the middle.
The Internet is a network of networks interconnected using TCP/IP and other communication protocols.
IP (Internet Protocol) Address
An IP address is a number identifying a particular computer on the Internet. In the previous version 4 of the Internet Protocol an IP address consisted of four bytes (32 bits), often represented as four integers in the range 0-255 separated by dots, such as 184.108.40.206. In IPv6, which the Net is currently switching to, an IP address is four times longer, and consists of 16 bytes (128 bits). It can be written as 8 groups of 4 hex digits separated by colons, such as 2001:0db8:85a3:0000:0000:8a2e:0370:7334.
IRC (Internet relay chat)
IRC is a more than 20-year-old Internet protocol used for real-time text conversations (chat or instant messaging). There exist several IRC networks -- the largest have more than 50 000 users.
ISP (Internet Service Provider)
An ISP (Internet service provider) is a business or organization that provides access to the Internet for its customers.
A keyword filter scans all Internet traffic going through a server for forbidden words or terms to block.
Latency is a measure of time delay experienced in a system, here in a computer network. It is measured by the time between the start of packet transmission to the start of packet reception, between one network end (e.g. you) to the other end (e.g. the Web server). One very powerful way of Web filtering is maintaining a very high latency, which makes lots of circumvention tools very difficult to use.
A log file is a file that records a sequence of messages from a software process, which can be an application or a component of the operating system. For example, Web servers or proxies may keep log files containing records about which IP addresses used these services when and what pages were accessed.
A low-bandwidth filter is a Web service that removes extraneous elements such as advertising and images from a Web page and otherwise compresses it, making page download much quicker.
Malware is a general term for malicious software, including viruses, that may be installed or executed without your knowledge. Malware may take control of your computer for purposes such as sending spam. (Malware is also sometimes called badware.)
man in the middle
A man in the middle or man-in-the-middle is a person or computer capturing traffic on a communication channel, especially to selectively change or block content in a way that undermines cryptographic security. Generally the man-in-the-middle attack involves impersonating a Web site, service, or individual in order to record or alter communications. Governments can run man-in-the-middle attacks at country gateways where all traffic entering or leaving the country must pass.
A middleman node is a Tor node that is not an exit node. Running a middleman node can be safer than running an exit node because a middleman node will not show up in third parties' log files. (A middleman node is sometimes called a non-exit node.)
To monitor is to check a data stream continuously for unwanted activity.
network address translation (NAT)
NAT is a router function for hiding an address space by remapping. All traffic going out from the router then uses the router's IP address, and the router knows how to route incoming traffic to the requestor. NAT is frequently implemented by firewalls. Because incoming connections are normally forbidden by NAT, NAT makes it difficult to offer a service to the general public, such as a Web site or public proxy. On a network where NAT is in use, offering such a service requires some kind of firewall configuration or NAT traversal method.
A network operator is a person or organization who runs or controls a network and thus is in a position to monitor, block, or alter communications passing through that network.
A node is an active device on a network. A router is an example of a node. In the Psiphon and Tor networks, a server is referred to as a node.
See middleman node.
Obfuscation means obscuring text using easily-understood and easily-reversed transformation techniques that will withstand casual inspection but not cryptanalysis, or making minor changes in text strings to prevent simple matches. Web proxies often use obfuscation to hide certain names and addresses from simple text filters that might be fooled by the obfuscation. As another example, any domain name can optionally contain a final dot, as in "somewhere.com.", but some filters might search only for "somewhere.com" (without the final dot).
An open node is a specific Psiphon node which can be used without logging in. It automatically loads a particular homepage, and presents itself in a particular language, but can then be used to browse elsewhere.
See also Psiphon node.
A packet is a data structure defined by a communication protocol to contain specific information in specific forms, together with arbitrary data to be communicated from one point to another. Messages are broken into pieces that will fit in a packet for transmission, and reassembled at the other end of the link.
A peer-to-peer (or P2P) network is a computer network between equal peers. Unlike client-server networks there is no central server and so the traffic is distributed only among the clients.This technology is mostly applied to file sharing programs like BitTorrent, eMule and Gnutella. But also the very old Usenet technology or the VoIP program Skype can be categorized as peer-to-peer systems.
See also file sharing.
PHP is a scripting language designed to create dynamic Web sites and web applications. It is installed on a Web server. For example, the popular Web proxy PHProxy uses this technology.
Plain text is unformatted text consisting of a sequence of character codes, as in ASCII plain text or Unicode plain text.
Plaintext is unencrypted text, or decrypted text.
See also encryption, SSL, SSH.
Protection of personal privacy means preventing disclosure of personal information without the permission of the person concerned. In the context of circumvention, it means preventing observers from finding out that a person has sought or received information that has been blocked or is illegal in the country where that person is at the time.
Post Office Protocol version 3 is used to receive mail from a server, by default on port 110 with an e-mail program such as Outlook Express or Thunderbird.
A hardware port on a computer is a physical connector for a specific purpose, using a particular hardware protocol. Examples are a VGA display port or a USB connector.
Software ports also connect computers and other devices over networks using various protocols, but they exist in software only as numbers. Ports are somewhat like numbered doors into different rooms, each for a special service on a server or PC. They are identified by numbers from 0 to 65535.
A formal definition of a method of communication, and the form of data to be transmitted to accomplish it. Also, the purpose of such a method of communication. For example, Internet Protocol (IP) for transmitting data packets on the Internet, or Hypertext Transfer Protocol for interactions on the World Wide Web.
A proxy server is a server, a computer system or an application program which acts as a gateway between a client and a Web server. A client connects to the proxy server to request a Web page from a different server. Then the proxy server accesses the resource by connecting to the specified server, and returns the information to the requesting site. Proxy servers can serve many different purposes, including restricting Web access or helping users route around obstacles.
A Psiphon node is a secured web proxy designed to evade Internet censorship. It is developed by Psiphon inc. Psiphon nodes can be open or private.
A private node is a Psiphon node working with authentication, which means that you have to register before you can use it. Once registered, you will be able to send invitations to your friends and relatives to use this specific node.
See also Psiphon node.
publicly routable IP address
Publicly routable IP addresses (sometimes called public IP addresses) are those reachable in the normal way on the Internet, through a chain of routers. Some IP addresses are private, such as the 192.168.x.x block, and many are unassigned.
A regular expression (also called a regexp or RE) is a text pattern that specifies a set of text strings in a particular regular expression implementation such as the UNIX grep utility. A text string "matches" a regular expression if the string conforms to the pattern, as defined by the regular expression syntax. In each RE syntax, some characters have special meanings, to allow one pattern to match multiple other strings. For example, the regular expression
An anonymous remailer is a service which allows users to send e-mails anonymously. The remailer receives messages via e-mail and forwards them to their intended recipient after removing information that would identify the original sender. Some also provide an anonymous return address that can be used to reply to the original sender without disclosing her identity. Well-known Remailer services include Cypherpunk, Mixmaster and Nym.
A router is a computer that determines the route for forwarding packets. It uses address information in the packet header and cached information on the server to match address numbers with hardware connections.
root name server
A root name server or root server is any of thirteen server clusters run by IANA to direct traffic to all of the TLDs, as the core of the DNS system.
RSS (Real Simple Syndication)
RSS is a method and protocol for allowing Internet users to subscribe to content from a Web page, and receive updates as soon as they are posted.
On the Web, a scheme is a mapping from a name to a protocol. Thus the HTTP scheme maps URLs that begin with HTTP: to the Hypertext Transfer Protocol. The protocol determines the interpretation of the rest of the URL, so that http://www.example.com/dir/content.html identifies a Web site and a specific file in a specific directory, and mailto:firstname.lastname@example.org is an e-mail address of a specific person or group at a specific domain.
A UNIX shell is the traditional command line user interface for the UNIX/Linux operating systems. The most common shells are sh and bash.
A SOCKS proxy is a special kind of proxy server. In the ISO/OSI model it operates between the application layer and the transport layer. The standard port for SOCKS proxies is 1080, but they can also run on different ports. Many programs support a connection through a SOCKS proxy. If not you can install a SOCKS client like FreeCap, ProxyCap or SocksCap which can force programs to run through the Socks proxy using dynamic port forwarding. It is also possible to use SSH tools such as OpenSSH as a SOCKS proxy server.
A screenlogger is software able to record everything your computer displays on the screen. The main feature of a screenlogger is to capture the screen and log it into files to view at any time in the future. Screen loggers can be used as powerful monitoring tool. You should be aware of any screen logger running on any computer you are using, anytime.
A smartphone is a mobile phone that offers more advanced computing ability and connectivity than a contemporary feature phone, such as Web access, ability to run elaborated operating systems and run built-in applications.
Spam is messages that overwhelm a communications channel used by people, most notably commercial advertising sent to large numbers of individuals or discussion groups. Most spam advertises products or services that are illegal in one or more ways, almost always including fraud. Content filtering of e-mail to block spam, with the permission of the recipient, is almost universally approved of.
SSH (Secure Shell)
SSH or Secure Shell is a network protocol that allows encrypted communication between computers. It was invented as a successor of the unencrypted Telnet protocol and is also used to access a shell on a remote server.
The standard SSH port is 22. It can be used to bypass Internet censorship with port forwarding or it can be used to tunnel other programs like VNC.
SSL (Secure Sockets Layer)
SSL (or Secure Sockets Layer), is one of several cryptographic standards used to make Internet transactions secure. It is was used as the basis for the creation of the related Transport Layer Security (TLS). You can easily see if you are using SSL/TLS by looking at the URL in your Browser (like Firefox or Internet Explorer): If it starts with https instead of http, your connection is encrypted.
Steganography, from the Greek for hidden writing, refers to a variety of methods of sending hidden messages where not only the content of the message is hidden but the very fact that something covert is being sent is also concealed. Usually this is done by concealing something within something else, like a picture or a text about something innocent or completely unrelated. Unlike cryptography, where it is clear that a secret message is being transmitted, steganography does not attract attention to the fact that someone is trying to conceal or encrypt a message.
A subdomain is part of a larger domain. If for example "wikipedia.org" is the domain for the Wikipedia, "en.wikipedia.org" is the subdomain for the English version of the Wikipedia.
A security threat analysis is properly a detailed, formal study of all known ways of attacking the security of servers or protocols, or of methods for using them for a particular purpose such as circumvention. Threats can be technical, such as code-breaking or exploiting software bugs, or social, such as stealing passwords or bribing someone who has special knowledge. Few companies or individuals have the knowledge and skill to do a comprehensive threat analysis, but everybody involved in circumvention has to make some estimate of the issues.
Top-Level Domain (TLD)
In Internet names, the TLD is the last component of the domain name. There are several generic TLDs, most notably .com, .org, .edu, .net, .gov, .mil, .int, and one two-letter country code (ccTLD) for each country in the system, such as .ca for Canada. The European Union also has the two-letter code .eu.
TLS (Transport Layer Security)
TLS or Transport Layer Security is a cryptographic standard based on SSL, used to make Internet transactions secure.
TCP/IP (Transmission Control Protocol over Internet Protocol)
TCP and IP are the fundamental protocols of the Internet, handling packet transmission and routing. There are a few alternative protocols that are used at this level of Internet structure, such as UDP.
A bridge is a middleman Tor node that is not listed in the main public Tor directory, and so is possibly useful in countries where the public relays are blocked. Unlike the case of exit nodes, IP addresses of bridge nodes never appear in server log files and never pass through monitoring nodes in a way that can be connected with circumvention.
Traffic analysis is statistical analysis of encrypted communications. In some circumstances traffic analysis can reveal information about the people communicating and the information being communicated.
A tunnel is an alternate route from one computer to another, usually including a protocol that specifies encryption of messages.
UDP (User Datagram Packet)
UDP is an alternate protocol used with IP. Most Internet services can be accessed using either TCP or UDP, but there are some that are defined to use only one of these alternatives. UDP is especially useful for real-time multimedia applications like Internet phone calls (VoIP).
URL (Uniform Resource Locator)
The URL (Uniform Resource Locator) is the address of a Web site. For example, the URL for the World News section of the NY Times is http://www.nytimes.com/pages/world/index.html. Many censoring systems can block a single URL. Sometimes an easy way to bypass the block is to obscure the URL. It is for example possible to add a dot after the site name, so the URL http://en.cship.org/wiki/URL becomes http://en.cship.org./wiki/URL. If you are lucky with this little trick you can access blocked Web sites.
Usenet is a more than 20-year-old discussion forum system accessed using the NNTP protocol. The messages are not stored on one server but on many servers which distribute their content constantly. Because of that it is impossible to censor Usenet as a whole, however access to Usenet can and is often blocked, and any particular server is likely to carry only a subset of locally-acceptable Usenet newsgroups. Google archives the entire available history of Usenet messages for searching.
VoIP (Voice over Internet Protocol)
VoIP refers to any of several protocols for real-time two-way voice communication on the Internet, which is usually much less expensive than calling over telephone company voice networks. It is not subject to the kinds of wiretapping practiced on telephone networks, but can be monitored using digital technology. Many companies produce software and equipment to eavesdrop on VoIP calls; securely encrypted VoIP technologies have only recently begun to emerge.
VPN (virtual private network)
A VPN (virtual private network) is a private communication network used by many companies and organizations to connect securely over a public network. Usually on the Internet it is encrypted and so nobody except the endpoints of the communication can look at the data traffic. There are various standards like IPSec, SSL, TLS or PPTP. The use of a VPN provider is a very fast secure and convenient method to bypass Internet censorship with little risks but it generally costs money every month.
A whitelist is a list of sites specifically authorized for a particular form of communication. Filtering traffic can be done either by a whitelist (block everything but the sites on the list), a blacklist (allow everything but the sites on the list), a combination of the two, or by other policies based on specific rules and conditions.
World Wide Web (WWW)
The World Wide Web is the network of hyperlinked domains and content pages accessible using the Hypertext Transfer Protocol and its numerous extensions. The World Wide Web is the most famous part of the Internet.
Webmail is e-mail service through a Web site. The service sends and receives mail messages for users in the usual way, but provides a Web interface for reading and managing messages, as an alternative to running a mail client such as Outlook Express or Thunderbird on the user's computer. For example a popular and free webmail service is https://mail.google.com/
A Web proxy is a script running on a Web server which acts as a proxy/gateway. Users can access such a Web proxy with their normal Web browser (like Firefox) and enter any URL in the form located on that Web site. Then the Web proxy program on the server receives that Web content and displays it to the user. This way the ISP only sees a connection to the server with the Web proxy since there is no direct connection.
WHOIS (who is) is the aptly named Internet function that allows one to query remote WHOIS databases for domain registration information. By performing a simple WHOIS search you can discover when and by whom a domain was registered, contact information, and more.
A WHOIS search can also reveal the name or network mapped to a numerical IP address