Networking

SPF - Sender Policy Framework

Sender Policy Framework (SPF) is an email authentication method designed to detect forged sender addresses in emails (email spoofing), a technique often used in phishing and email spam. SPF allows the receiver to check that an email claiming to come from a specific domain comes from an IP address authorized by that domain's administrators.

Networking Security

What is email envelope and email header

The key for understand smtp protocol is learn, what is difference between email envelope and email header. Another words, what is email envelope vs email header.

Networking Security

How to Test an SMTP Server with Telnet command line

How to test SMTP and IMAP servers using the telnet command-line

Linux Networking Windows

Nginx Location Priority Manual

The location directive within NGINX server block allows to route request to correct location within the file system. The directive is used to tell NGINX where to look for a resource by including files and folders while matching a location block against an URL. In this tutorial, we will look at NGINX location directives in details.

Linux Networking Web Servers

Test IMAP with telnet

You may wish to test IMAP commands against the IMAP service. This article decribes how this can be done. This example has been tested with debian stable distro, but should work same or similar with any Linux or Windows machine.

Networking Linux

Arpwatch - monitor mac addresses change

Arpwatch is a computer software open source program. It monitors the ARP activity over the network and detects ARP spoofing. It also maintains the database of Ethernet/IP address pairings. Arpwatch gives a list of noticed pairing IP and MAC addresses. Techniques to monitor Ethernet Activity using Arpwatch Tool in Linux is illustrated in this tutorial with examples.

Networking Linux Security

Installation of LTE modem into Turris Omnia router

Guide how to setup turris omnia with lte modem. This manual is intended to be used with the modem we provide in retail as a part of the LTE kit or as a part of Omnia 4G. In case you use any other modem PCIe card, this might not apply.

Networking

How To Refresh an Access Token Using Decorators

When I was creating a one script, which uses JWT for authentication, I began to run into challenges with longer scripts that extended beyond the expiration of a single JWT.

To elegantly solve this, I used decorators to check the token’s expiration and request a new token if necessary. This article goes over the framework I set up so that you can apply a similar mechanism in your own scripts.

Setting the Scene

To get started, I’ve outlined all the parts needed to set up our token-refreshing framework.

Python Development Networking

How use Python retry decorator function with API

An ever-increasing proportion of a typical company’s infrastructure is moving to the cloud. More companies are shifting towards a micro-service approach. These paradigm shifts away from local to cloud-based means that you probably also have faced a situation where you had to pull data from somewhere or write data somewhere that is not your local computer.

On a small scale, there rarely are problems around that. If some extraction or writeback fails, you would typically notice that and would be able to remedy the mistake. But, as you move towards larger-scale operations and potentially hundreds of thousands of transactions, you don’t want to get screwed over by a temporary drop of internet-connection, too many concurrent writes, a temporarily unresponsive source system, or god knows what else.

Python Development Networking

Active and Passive FTP Simplified - Understanding FTP Ports

File transfer protocol (FTP) is a popular application-layer protocol that is used for file transfers across TCP networks. FTP supports two modes: active and passive. These modes use different connection mechanisms, and each require different firewall configurations to allow access. This article discusses the differences between these modes.

Networking Security

OCSP Stapling on Nginx and Apache webserver

To understand OCSP stapling, it is necessary to understand OCSP, the Online Certificate Status Protocol. OCSP is a protocol for determining whether a certificate is revoked (for instance, becau se its private key was compromised). Every time a browser connects to an HTTPS website, it contacts the OCSP responder specified in the SSL certificate, and asks if the certificate is revoked. If the respond er replies that the certificate is revoked, the browser blocks the page from loading.

Web Servers Networking Security

ProFTPd Server with virtual users and in SFTP mode

How to configure proftpd server with virtual users and with sftp mode.

Debian Linux Networking Security