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todayOctober 8, 2021

How To's + Postfix taylor

Postfix BCC All Incoming Mail For User or Domain

In this article we’re going to learn how to configure Postfix to BCC all incoming mail for a domain or specific user. First, let’s create the following file in Postfix with the following command: nano /etc/postfix/recipient_bcc_maps To BCC all incoming mail for a single domain, use the following: *@example-a.tld [email protected] [...]






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Background

We’re Out Of Space!

Global news + Network Basics taylor todayApril 16, 2021 121

Background
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Experts predict that in two or three years we will run out of Web addresses (theoretically, we already have), so-called IP addresses, that can be assigned to new Internet-based sites and services. This is a problem… a big problem.

What is an IP Address?

For simplicity’s sake, we’ll use the mail service as an example. Naturally, in order for any parcels to be delivered to the correct location they need to know where it is going. Hence, mailing addresses were conceived. IP Addresses operate in a similar fashion. In order for the internet to function properly as we all know it, your devices need to know who or where to request and send data to/from.

The structure of the IP address we’re all familiar with (IPv4) can be likened to that of multiple apartment complexes (255 of them to be exact). Now, this is where it starts to get tricky, follow along: Inside of those 255 apartment complexes, there are another 255 apartment complexes, with another 255 apartment complexes containing only 255 individual units. In essence, this means there are a total of 4,294,967,296 (232) individual addresses we can send a parcel to. That’s plenty, right?! Well, not so much in today’s digital age.

In a press release from research firm Strategy Analytics, it was predicted that by 2020 there will be approximately 33 billion devices in-use. In other words, 4.3 devices per-person on the planet. Now, if we do the math from our total number of IP addresses (4,294,967,296 – 33,000,000,000), that leaves us a little short, right? Absolutely.

We figured out this issue early on and knew not to assign a unique IP address for every device connected to the internet, but rather divvy the public addresses up between Internet Service Providers (ISP’s) and leave a few subnets available for private use.

What’s the Difference Between a Public and a Private IP Address?

In order for you to view this article, your computer had to make a series of requests to our server in order to receive the data you’re viewing right now. Now, to keep this simple, I’m redacting/re-wording some steps, but nonetheless you’ll have a solid grasp of the whole concept.

When you type “www.google.com” into your web browser’s address bar and hit enter, your computer sends a request to the router in your home or business. Your router then forwards that request to your ISP who in turn converts “www.google.com” to one of Google’s many IP Addresses and forwards your request for data on to them. Once one of Google’s servers receives your request it gathers all the data you want, and sends it back to your ISP. Your ISP then returns the data to your router, and your router delivers the website to your computer which converts it into the search page we all know and love (for the most part… kind of).

Your computer communicates with your router using what’s called a “Private Address”. These addresses (should) lie within one of the following ranges:

  • 10.0.0.0/8 IP Addresses: 10.0.0.0 – 10.255.255.255
  • 172.16.0.0/12 IP Addresses: 172.16.0.0 – 172.31.255.255
  • 192.168.0.0/16 IP Addresses: 192.168.0.0 – 192.168.255.255

These addresses are specially reserved for local home or business networks. This means these addresses cannot be queried from the public-facing internet. Meaning, if your phone’s IP address on your router is 172.16.1.5, I can’t reach it from my local network by directly attempting to access that IP address (emphasis, on directly).

Now, the communication that took place between your ISP and Google’s ISP was via the Public IP address space. This space encompasses every IP address starting at 1.0.0.0/8 to 223.0.0.0/8 excluding the addresses which were outlined above (to a degree). You can view a list of all the available IPv4 Addresses and who they’re registered to here.

So, we’re out of IP Addresses… What’s Next? IPv6, of course!

In order to best explain IPv6, let’s take a look at the semi-technical details of an IPv4 address such as 172.16.254.1 for example. This address expresses a 32-bit integer value written in dot-decimal notation:

This notation is four octets expressed individually in decimal numbers separated by periods. Each octet consists of 8 bits or 1 byte. All together, the address equals 32 bits or 4 bytes.

Composition of an IPv6 Address

You’ve probably already noticed the most significant difference in IPv6 vs. IPv4: It’s much larger… Four-times as-large, to be exact. IPv6 is composed of 8 quartets containing 16 bits each equaling 128 bits or 16 bytes per address. A key takeaway is, IPv4 and IPv6 are not compatible with each other. You can use both concurrently, but IPv4 cannot communicate with an IPv6 address and vice-versa.

I won’t dive into the technicalities of IPv6 composition, but if you want to learn more you can do so here

In comparison to IPv4, though IPv6 may seem more complicated, it provides significantly more available addresses as well as many additional features that are otherwise impossible with IPv4. Additionally, it significantly simplifies quite a few aspects regarding address configuration and network renumbering as well as improving router efficiency by placing the responsibility for packet fragmentation into the end points. IPv6 allows for approximately 2128 (3.4×1038 or 340,282,366,920,938,000,000,000,000,000,000,000,000) unique IP addresses. Now, that’s a lot.

This would allow for approximately 44,342,242,000,000,000,000,000,000,000 IP addresses per-person on the planet (Math Check: 2^128 / 7674000000)

The last unassigned top-level address blocks of 16 million IPv4 addresses were allocated in February 2011 by the Internet Assigned Numbers Authority (IANA) to the five regional Internet registries (RIRs). However, each RIR still has available address pools and is expected to continue with standard address allocation policies until one /8 Classless Inter-Domain Routing (CIDR) block remains. After that, only blocks of 1024 addresses (/22) will be provided from the RIRs to a local Internet registry (LIR). As of September 2015, all of Asia-Pacific Network Information Centre (APNIC), the Réseaux IP Européens Network Coordination Centre (RIPE_NCC), Latin America and Caribbean Network Information Centre (LACNIC), and American Registry for Internet Numbers (ARIN) have reached this stage. This leaves African Network Information Center (AFRINIC) as the sole regional internet registry that is still using the normal protocol for distributing IPv4 addresses. As of November 2018, AFRINIC’s minimum allocation is /22 or 1024 IPv4 addresses. A LIR may receive additional allocation when about 80% of all the address space has been utilized. RIPE NCC announced that it had fully run out of IPv4 addresses on 25 November 2019, and called for greater progress on the adoption of IPv6. It is widely expected that the Internet will use IPv4 alongside IPv6 for the foreseeable future. [Source]

Get Your Network IPv6 Ready!







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