Illustrated introduction to Linux iptables Gee, it's my turn to throw some light on iptables! There are hundreds or even thousands of articles on the topic out there, including introductory ones. I'm not going to put either formal definitions here nor long lists of useful commands. I would rather try to use layman's terms and scribbling as much as possible to give you some insights about the domain before going to all these tables, rules, targets, and policies. Networking
A Visual Guide to SSH Tunnels: Local and Remote Port Forwarding SSH is yet another example of an ancient technology that is still in wide use today. One of my favorite parts of this technology is SSH Tunnels... Networking
Bridge vs. Switch The difference between these two networking devices has been an unsolvable mystery to me for quite some time. For a while, I used to use the words 'bridge' and 'switch' interchangeably. But after getting more into networking, I started noticing that some people tend to see them as rather different devices... So, maybe I've been totally wrong? Maybe saying 'bridge aka switch' is way too inaccurate? Networking
Computer Networking Introduction: Ethernet and IP This article is my layman's attempt to sort the basic things out with the minimum words and maximum drawings. The primary focus will be on the Data link layer (OSI L2) of wired networks where the Ethernet is the king nowadays. But I'll slightly touch upon its neighboring layers too. Networking
BIND: Disabling IPv6 responses in bind dns server When using Bind9 as DNS service in your own network, it can be helpful to disable IPv6 (AAAA) responses to avoid the client to try to communicate via IPv6 if it hasn't been setup. Debian Linux Networking
BIND DNS server - permission denied How Fix BIND DNS server permission denied problem after log directory or log file change. Bind server failed with error: isc_stdio_open failed: permission denied Debian Linux Networking
Bonding - teaming 802.3ad LACP on Debian Server NIC teaming (Ling Aggregation) presents an interesting solution to redundancy and high availability in the server/workstation computing realms. With the ability to have multiple network interface cards, an administrator can become creative in how a particular server accessed or create a larger pipe for traffic to flow through to the particular server. Debian Linux Networking
Debian - Source Routing In some circumstances we want to route packets differently depending not only on ip destination addresses, but also on other packet fields: source address, IP protocol, transport protocol ports, or even packet payload. This task is called policy based routing - PBR. Debian Linux Networking
Debian Permanent Static Routes In this tutorial we are going to learn how to add permanent (persistent) static route in Debian or Ubuntu Linux. Debian Linux Networking
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
