China
Africa
Explore chapters and articles related to this topic
High-Performance Switch/Routers
Published in James Aweya, Designing Switch/Routers, 2023
Local SSH Port Forwarding allows a user to connect a local client application to an external network. A user may use SSH Port Forwarding to access an IMAP (Internet Message Access Protocol) server running on a remote host in a company network from an email client running on the home machine. A user may use Port Forwarding to connect to a database that is behind a firewall or to access websites that are blocked locally.Configuring Local SSH Port Forwarding: When a connection is received on a locally forwarded port, a message is sent to the other side indicating the following: SSH_MSG_CHANNEL_OPEN, “direct-tcpip”, sender’s channel number, initial data window size, maximum packet size, the local host IP address and port, the IP address (or hostname) and the port of the destination host, and the remote SSH user and SSH server IP address. Note that a side may also send these messages for ports for which no forwarding has been explicitly requested [RFC4254]. The receiving side must make the decision on whether to allow the forwarding to take place.Forwarded TCP/IP channels are independent of any session channels, meaning closing a session channel does not lead to the closing of forwarded connections.
Introduction of Computer Networks
Published in Dijiang Huang, Ankur Chowdhary, Sandeep Pisharody, Software-Defined Networking and Security, 2018
Dijiang Huang, Ankur Chowdhary, Sandeep Pisharody
Dropping the letter into a mailbox of a local post office is equivalent to clicking on the “send” button on the email client. The letter will be usually first sorted at the local post office based on the receiver's address to decide when and how to deliver (i.e., put the letter in a scheduled delivery truck to the next delivery hub), in which the sorting is based on the “scope” of the destination: international vs. domestic, city and street names or a zip code. Once the letter arrives at the destination's local post office, the letter distributor will check the receiver's home number and street name for the final delivery. This procedure is similar to what the Internet Protocol (IP)IP-based packet switching network uses to deliver an end-to-end packet that encapsulates the email content. Routers serve as counterparts for post offices and mail delivery hubs, while the transmission protocol serves the purpose of the mail delivery truck. In an IP packet, source IP address and destination IP address serve the purpose of sender's address and receiver's address for mail delivery, respectively. An IP address has a two-level data structure: the network address and host address, which can be mapped to the zip code, city, and street names; and home number, respectively. Internet routers only look at the network address to deliver the message to the destination's local network, and once arrived, the host address is used to deliver the message to the destination host.
A Comparative Analysis and Discussion of Email Spam Classification Methods Using Machine Learning Techniques
Published in Nilanjan Dey, Sanjeev Wagh, Parikshit N. Mahalle, Mohd. Shafi Pathan, Applied Machine Learning for Smart Data Analysis, 2019
Aakash Atul Alurkar, Sourabh Bharat Ranade, Shreeya Vijay Joshi, Siddhesh Sanjay Ranade, Gitanjali R. Shinde, Piyush A. Sonewar, Parikshit N. Mahalle
To reiterate the need for a sufficient classifier, it is useful to imagine a world where spam classifiers do not exist. Around two hundred billion messages continue to get sent daily, and sorting out the important ones necessitates users manually clicking each one and deleting them by themselves. Just imagining such a situation can be stressful. This is because a spam classifier has quietly become one of those features that we have collectively begun relying on without even noticing its presence. Another exercise would be to open any Inbox and go to the spam section. The hundreds of spam emails, advertisements, offers, and so on in that section makes one realize how much clutter has been hidden from the user’s eyes. Also consider, for example, a situation where a layperson receives an email, asking for update of the user’s bank account details via a provided link, which does not appear suspicious to the user because it appears to have been sent by the user’s bank and looks authentic. The user then visits the link and updates all details, unaware that she/he has been the most recent victim of a phishing attack. Upon realizing this mistake, the user contacts the required authorities (such as the cyber security cell of the state) who may or may not succeed in remedying the situation and identifying the perpetrators. Now imagine if, in the same situation, the user’s email client employed a more accurate spam filter. The email from the “bank” would be identified as inauthentic, based on features such as the authentication of the email id, the number of HTML tags used, spam keywords, and so on. Basically, it would go straight to spam and get deleted a few days later. The user would never find out she/he received this email, and hence there would be no damage.
A Cross-organizational Ecology for Virtual Communities of Practice in Higher Education
Published in International Journal of Human–Computer Interaction, 2020
Aekaterini Mavri, Andri Ioannou, Fernando Loizides
Wenger’s framework (Wenger et al., 2009) for virtual Communities of Practice (VCoPs) (Hafeez et al., 2019) asserts that technology comprises four components: tools, features, platforms and configurations: a) tools: software for specific purposes (i.e. an email client) (Cherry & Latulipe, 2014); b) platforms: packages that combine tools (Spagnoletti, Resca, & Lee, 2015) like for instance Google’s G Suite (“G Suite: Collaboration & Productivity Apps for Business,” n.d.), used for communication, productivity and storage, with common access and functionality; c) features: specific properties supported by the user interface (i.e. filtering, sorting); and d) configuration: the entire arrangement of the above-mentioned platforms and tools. A course could employ, for instance, a Learning Management System (LMS), supported by a social network (SN) (deChambeau, 2017; Gunawardena et al., 2009), as well as domain-specific software, like a Creativity Support Tool (CST) to accommodate the specific needs of a domain (Cherry & Latulipe, 2014). For the purposes of this work, CSTs refer to software for the development of creative artifacts e.g. a written article or a design item.
An M/G/1 queue with two types of general heterogeneous service and optional repeated service subject to server’s breakdown and delayed repair
Published in Quality Technology & Quantitative Management, 2018
Gautam Choudhury, Chandi Ram Kalita
Consider a digital communication network system, where mail server transmits the email data from one station to another station. In emailing process, the Mail servers can be broken down into two main categories: outgoing mail servers and incoming mail servers. Outgoing mail servers are known as SMTP, or Simple Mail Transfer Protocol, servers. Incoming mail servers come in two main varieties. POP3, or Post Office Protocol, version 3, servers are best known for storing sent and received messages on PCs’ local hard drives. IMAP, or Internet Message Access Protocol, servers always store copies of messages on servers. After composing a message and hitting send, sender’s email client – whether it’s Outlook Express or Gmail – connects to its domain’s SMTP server. The sender’s email client communicates with the SMTP server, giving it sender’s email address, the recipient’s email address, the message body and any attachments. The SMTP servers process the recipient’s email address – especially its domain and then perform two types of job. In the first type of job it routed the message directly over to the domain’s POP3 or IMAP server, if the domain name is same as the sender’s and in the second type of job the SMTP server send message to the other domain’s server (DNS) if the domain name is different with sender’s. Typically, message processing request arrive at the SMTP server following Poisson stream and message can select any one of the two types of service at the SMTP server (depending upon the choice of the sender, the sender may send message with same or different domain name as recipient’s). The sender can resend the message again due to failure of the previous sending. In practice message processing request may fail due to failure of the SMTP server. After failure of the SMTP server, the server can be repaired. The repair time depends on the degree of failure of the SMTP server. Because the system performance may be heavily affected by SMTP server breakdown, it is well worth to investigate such system from the queueing theory point of view, as well as reliability point of view. In this scenario, the SMTP server, two types of job by SMTP server, message resend correspond to the server, two types of service and repeated service in the queueing terminology.