Refers to the 4th revision of the Internet Protocol, where addresses are usually displayed in the form of dotted decimals between 0-255. Ex: 169.254.0.1

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168
votes
13answers
30k views

Why couldn't MAC addresses be used instead of IPv4|6 for networking? [closed]

I am reading up on TCP/IP and other related protocols and technologies. MAC addresses are described as being (reasonably :) unique, and as having a large possibility space (several hundred trillions), ...
34
votes
5answers
5k views

Is it valid to have part of an IPv4 address set to zero?

I am working on a change in a Java EE application that would authenticate based on the user's IP address using ServletRequest.getRemoteAddr. We store IP address ranges (FROM_IP and TO_IP) in a ...
27
votes
3answers
10k views

What is the rest of the 127.0.0.0/8 address space used for?

We all know what 127.0.0.1 is used for (loopback). But is the rest of the reserved 127.0.0.0/8 loopback space widely used for anything?
26
votes
8answers
5k views

What's the maximum number of IPs a DNS A record can have?

I have a strange idea - let multiple people/organizations host the same application, and let all their nodes be accessible via a single domain name. That's in order to have, let's say, a really ...
22
votes
2answers
2k views

New service decision: IPv6 or IPv4?

While hosting new service these days, what would be best decision. IPv4 or IPv6 ? If we decided to launch it on IPv4 address: How easy/difficult to get IPv4 address (considering they getting ...
17
votes
2answers
1k views

Is an IPv6-only MTA possible yet?

Has anyone had tried to run an IPv6-only SMTP engine? Pretty much everybody with any sense has IPv6 configured for major front-end servers. I was curious if anyone had tried to run an IPv6-only MTA ...
16
votes
5answers
1k views

IPv6: How to start? (ISP perspective)

In our company we have a range of /21 (2048) IPv4 public addresses. We have a bunch of Cisco routers and servers. How to get started with IPv6? What can we do to provide internet to our clients with ...
16
votes
3answers
1k views

How do I make actual use an IPv4 block that I own?

We (a small French company) had reserved an IPv4 /24 block (256 addresses) from RIPE-NCC, over 20 years ago, but never used it. Update: our assignment belongs to the "Provider Independent (PI) address ...
14
votes
3answers
10k views

Do you need separate ipv4 and ipv6 listen directives in nginx?

I've seen various config examples for handling dual-stack ipv4 and ipv6 virtual hosts on nginx. Many suggest this pattern: listen 80; listen [::]:80 ipv6only=on; As far as I can see, this achieves ...
12
votes
4answers
621 views

How to prepare (or not) small company to IPv6

There's an ongoing "panic" all over the news for some time now about IPv4 running out and IPv6 being the savior. All the big companies are preparing and showing how it should be done (last actions ...
10
votes
2answers
1k views

Prefer IPv4 incoming connections over IPv6

We run a social/local service that benefits from geolocating the IP of users. The problem is that with IPv6, geolocation is quite a bit spottier than with IPv4. Is there a way to prefer incoming ...
8
votes
7answers
1k views

Best choice of private addresses for a “device area network”

I'm building an appliance consisting of several subdevices connected by ethernet inside the appliance. The appliance will connect to the customer network. The customer network can be using private ...
8
votes
5answers
6k views

Why is ipv6 128bit and not 64bit?

Computer processors moved from 32bit to 64bit. Why have IPs moved from 32bit to 128bit (skipping 64bit) ? EDIT: I did not intend to make a direct comparison. Just curious why IPs skipped 64bit.
8
votes
2answers
1k views

American Users have wrong IP address geolocation

In order to display the right content for my users I get their country based on their IP address. I have been receiving several reports from American users saying that the content is being displayed ...
8
votes
4answers
4k views

Why can't I ping an address on the loopback device under FreeBSD?

From Wikipedia: The most commonly used IP address on the loopback device is 127.0.0.1 for IPv4, although any address in the range 127.0.0.0 to 127.255.255.255 is mapped to it. This is not ...
8
votes
3answers
4k views

How to completely disable IPv4 stack from Linux?

How can I disable IPv4 stack from Linux ? I want to do that dynamically, ie. sometimes I want it enabled and sometimes I want only IPv6 stack. Is there any portable way to do that ? If you know how to ...
8
votes
3answers
3k views

What determines whether the FQDN is interpreted as IPv6 or IPv4?

When I type a Fully Qualified Domain Name (FQDN) in my URL bar, the browser connects to some mapping table (where is this table stored? with the service provider?) that determines where the file ...
7
votes
4answers
2k views

CIDR Ranges for Everything except RFC1918

I'm looking for a list of CIDR blocks for "The Internet", i.e. everything from 0.0.0.0 to 223.255.255.255, excluding RFC1918 address space of 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 (yes, I know ...
7
votes
5answers
385 views

No IPv6 & DNSSEC support on cc-TLD? (practical implications)

I'm needing to register some domains that have country code domain extensions, but noticed that those TLDs do not officially support (A) IPv6 or (B) DNSSEC... What limitations or pitfalls should I ...
7
votes
4answers
8k views

Advantages of IPv4 over IPv6

In theory, how IPv4 is better than IPv6? I need only advantages of IPv4 for study purposes. In another words - what are the pros of IPv4?
7
votes
2answers
489 views

IPv6 / IPv4 Third Form conversion?

I'm reading about how to configure IPv6 on Ubuntu, I've gotten to the section about Reading IPv6 Addresses and though the first two examples make sense to me, the last one escapes my grasp a bit, as ...
6
votes
4answers
8k views

Networking Question - What is a VALID Subnet Address? [duplicate]

Possible Duplicate: How does IPv4 Subnetting Work? I am currently revising Networking for the Cisco CCNA1. One of the questions that I am struggling to answer is the following: Which of ...
6
votes
2answers
4k views

Docker will only bind forwarded ports to IPv6 interfaces

Is there a way I can tell docker to only bind forwarded ports to IPv4 interfaces? I have a machine running on Digital Ocean with IPv6 disabled: # echo '1' > ...
6
votes
1answer
2k views

Multicast hostname lookups on OSX

I have a problem with hostname lookups on my OSX computer. According to Apple's HK3473 document it says for v10.6: Host names that contain only one label in addition to local, for example ...
6
votes
0answers
2k views

IPv6: the end of NAT? [duplicate]

Possible Duplicate: Switch to IPv6 and get rid of NAT? Are you kidding? Is NAT going to disappear with IPv6? What about during the "transition" from IPv4-IPv6? How are we all going to ...
5
votes
3answers
31k views

What Causes IPV6 To Be Used Instead Of IPV4?

I have two servers both running Windows 2008 with IPV4 and IPV6 both running. If on server1 I ping server2 like this ping server2 The response I get is Pinging server2 [2002:9b08:a21::9b08:a21] ...
5
votes
1answer
558 views

IP Address keeps getting assigned that is already in use

I have an internal IP Address (192.168.0.57) that every couple of days will get assigned to a machine which will then periodically lose it's connection to the network throughout the day. The first ...
5
votes
1answer
804 views

IPv6 working fine, IPv4 throws OpenSSL error

I am building a webserver ( http://blog.linformatronics.nl/ ), which functions just fine on both IPv4 and IPv6 and when using a non-SSL connection. However when I connect to it through https, IPv6 ...
5
votes
3answers
6k views

Disabling IPv4 and use only IPv6 in Ubuntu

I'm doing some IPv6 related testing, and I wanted to fully disable my IPv4 for the tests on Linux, but couldn't find any easy place to do this. How do I make my IPv6 the only active one?
5
votes
4answers
695 views

Enterprise IPv6 Migration - End of proxypac ? Start of Point-to-Point ? +10K users

Let's start with a diagram : We can see a "typical" IPv4 company network with : An Internet acces through a proxy An "Others companys" access through an dedicated proxy A direct access to local ...
5
votes
1answer
774 views

IPv6: Should I have private addresses?

Right now, we have a rack of servers. Every server right now has at least 2 IP addresses, one for the public interface, another for the private. The servers that have SSL websites on them have more IP ...
4
votes
2answers
372 views

For IPv6 migration, should we replace existing L2 switches running VLANs?

My L3 Core switch, Nortel ERS 8600, is IPv6 compatible. However, during migration to IPv6, do we need to also check the compatibility of edge/distribution switches in a VLAN-based campus network?
4
votes
2answers
1k views

IPv4 NameVirtualHost, IPv6 VirtualHost

Like many of us, I have an apache server (2.2.15, plus patches) with a lot of virtual hosts on it. More than I have IPv4 addresses, to be sure, which is why I use NameVirtualHost to run lots of them ...
4
votes
2answers
338 views

Empty AAAA DNS Record with long TTL?

I pay for a DNS service based on queries per second. We are not using IPv6, but a large number of queries (that I pay for) are coming in for AAAA records. I understand that most DNS stacks will now ...
4
votes
3answers
312 views

Make reachable via a fixed address (e.g. IPv6) a server that is actually connected via a variable IPv4 adress?

Need: Internet host at a fixed IP address for full-stack self-hosting People want to perform self-hosting in an area where no ISP provide sufficient service with a fixed IP address. They provide one ...
4
votes
1answer
938 views

Renting a IPv4 address block [closed]

I am building a lab network with about 10 virtual routers and 20 host machines (also virtualized) as a part of a school project. The aim is to demonstrate a wide range of IPv6 routing, deployment and ...
4
votes
2answers
3k views

how does ping resolve to ipv4 on one machine, but ipv6 on another?

Background I have two environments, TEST and STAGE. I use Microsoft Distributed Transaction Coordinator (MS DTC) with two linked 2008 SQL servers. A SQL job runs every couple of minutes and ...
4
votes
2answers
29k views

Domain connection shows as “unauthenticated”

I have seen various different questions for this problem floating around but either the circumstances arent the same or the solution doesnt work so thought i would post it to see if anybody has any ...
4
votes
4answers
2k views

Can a global IPv6 address be NAT'd to an internal IPv4 address at a firewall-level?

As an organisation we've just requested our first IPv6 allocation. At present we are a wholly IPv4 organisation with a global IPv4 address allocation configured on our edge router and used ...
3
votes
1answer
179 views

IPv4 is almost out in Asia-Pacific, what are people doing about it? [closed]

Asians and those in North America are going to be separated on the internet if ISPs / telecoms don't do something. European progress to IPv6 is taking place much faster than in North America. What ...
3
votes
5answers
359 views

Where to find information on the IPv4 crunch, why to worry, what to do?

Where do I get information on the IPv4 crunch (what will happen, transition to IPv6, etc.)? What should one do to prepare (if anything)? Ars Technica ran "A decade's worth of IPv4 addresses" and ...
3
votes
2answers
1k views

Laptop being assigned IPv4 address out of router's DHCP range

I have a laptop connecting wirelessly to an E4200 Linksys router. The router is configured to use DHCP with a range from #.#.#.100 to #.#.#.254. However, the laptop is being assigned an IP address of ...
3
votes
3answers
809 views

How does anycast work with tcp?

TCP, being stateful, should require subsequent packets to reach the same server. (Stateless) HTTP runs on top of TCP, and CDN's can use anycast. So how does TCP work with anycast? What if the syn ...
3
votes
1answer
3k views

Ping IPv4 addresses from an IPv6 host

So, I've been given to believe that IPv6-only clients can access IPv4 servers by using addresses like: ::ffff:0:74.125.226.80 (that would be an address for google.com). I'm not IPv6 yet, but I may be ...
3
votes
1answer
3k views

Disable IPv4: What exactly does 'ifconfig eth0 0' do?

I'm experimenting with Linux and networks. What I'm trying to do is disable IPv4 for remote connections. It shouldn't be that complicated but I didn't find much about this topic. However, there is one ...
3
votes
1answer
505 views

Subnet Masking in IPv6

I know within IPv4 subnet masking, the network is determined by either the 1st, 2nd or 3rd set of octets. Being there are so many more characters in IPv6, how do you determine the subnet mask?
3
votes
5answers
450 views

Isn't NAT a MUST when a LAN uses rfc 1918 private IPs?

Isn't NAT a MUST when a LAN uses rfc 1918 private IPs? Can an organization assign its hosts with private IPs and still communicate with the external world without NAT? how can an internal host with a ...
3
votes
1answer
8k views

Open Windows Firewall to all connections from specific IP Address

Is it possible to "whitelist" an IP Address in the Windows Firewall and allow all connections from that specific address?
3
votes
1answer
255 views

Why doesn't this IPv6 listen directive also accept IPv4?

In my nginx (1.4.2) setup on Ubuntu 12.04, I have set up only one configuration file (I deleted/disabled the others): server { listen [::]:80 default_server; location / { root ...
3
votes
1answer
37 views

Why doesn't the IETF reallocate IPv4 netblocks from regions that are over supplied?

I just was looking at the Hurricate Electric website, and it says that ARIN is out of IPv4 addresses. Meanwhile LACNIC, APNIC, RIPE, and AfiNIC have millions of unallocated IPv4 addresses. I did a ...