DMARC - Domain-based Message Authentication, Reporting and Conformance What is DMARC DMARC (Domain-based Message Authentication, Reporting, and Conformance) is an email authentication method that verifies a message came from a legitimate sender. DMARC is an open standard for email authentication that helps to prevent fraudsters from forging (spoofing) your domain. DMARC checks that the From field matches the domain in DKIM and SPF authentication checks. DMARC also tells email servers how to handle messages that fail these checks and allows recipients to receive reports on emails that fail authentication. Networking Security
Explanation DKIM (DomainKeys Identified Mail) in all details DKIM (DomainKeys Identified Mail) is a system that lets your official mail servers add a signature to headers of outgoing email and identifies your domain’s public key so other mail servers can verify the signature. As with SPF (Sender Policy Framework helps keep your mail from being considered spam. It also lets mail servers detect when your mail has been tampered with in transit. Networking Security
SPF - Sender Policy Framework Email Message Structure To understand how SPF (Sender Policy Framework) and DKIM works is to know the difference between email envelope and email header . Short Definition: Sender Addresses in E-Mails Like paper mail letters, e-mail messages have at least two kinds of sender addresses: one on the envelope and one in the letterhead. The envelope sender address (sometimes also called the return-path) is used during the transport of the message from mail server to mail server, e. 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
Nginx TLS TCP Proxy server for tcp upstream servers What is SSL Termination SSL/TLS termination means that NGINX acts as the server-side SSL/TLS endpoint for connections with clients: it performs the decryption of requests and encryption of responses that backend servers would otherwise have to do. The operation is called termination because NGINX closes the client connection and forwards the client data over a newly created, unencrypted connection to the servers in an upstream tcp servers. In release R6 and later, NGINX performs SSL/TLS termination for TCP connections as well as HTTP connections. Web Servers Security
Arpwatch - monitor mac addresses change Arpwatch Arpwatch is an open source computer software program that helps you to monitor Ethernet traffic activity (like Changing IP and MAC Addresses) on your network and maintains a database of ethernet/ip address pairings. It produces a log of noticed pairing of IP and MAC addresses information along with a timestamps, so you can carefully watch when the pairing activity appeared on the network. It also has the option to send reports via email to an network administrator when a pairing added or changed. Networking Linux Security
Python - How To Refresh an JWT Access Token Using Decorators When you create a big python application, you can began to run into challenges with longer scripts that extended beyond the expiration of a single JWT. To elegantly solve this, You can use 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 import time import requests class myAPI(): host = None key = None secret = None access_token = None access_token_expiration = None def __init__(self,host,key,secret): # the function that is executed when # an instance of the class is created pass def getAccessToken(self): # the function that is # used to request the JWT pass class Decorators(): @staticmethod def refreshToken(decorated): # the function that is used to check # the JWT and refresh if necessary pass Our class will work by requiring the fields necessary to request the JWT. Python Security Development
Active and Passive FTP Simplified - Understanding FTP Ports Active and Passive FTP Simplified - Understanding FTP Ports If a client encounters problems when connecting to your FTP server , one of the first things you might want to check is your FTP data transfer mode . Depending on certain network configurations, this mode should be set to either active or passive. In this post, you’ll understand the salient points of active and passive FTP and learn how to avoid connectivity issues associated with them. Networking Security
Certbot - Let's Encrypt certificates on Debian server with Apache webserver How install and use certbot on Debian system, examples how create Let's Encrypt certificates for multiple domains, how handling certbot automatic renewal. It covers a apache2 webserver configuration for using cerbot generated certificates. Setup is made for Debian and debian based linux distributions Linux Debian Security Web Servers
Certbot and Let’s Encrypt CA What is Certbot, cerbots commands and user guide, what is Let's Encrypt Rate Limits. How works cerbot authenticators and installers, certbot commands exmaples Linux Security Web Servers
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