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

learn more… | top users | synonyms

150
votes
13answers
25k 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), ...
33
votes
5answers
3k 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 ...
21
votes
3answers
5k 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?
14
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 ...
12
votes
4answers
589 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 ...
8
votes
3answers
2k 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
856 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
7answers
885 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 ...
7
votes
4answers
4k 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
4answers
2k 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 ...
7
votes
2answers
348 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
5answers
3k 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.
6
votes
4answers
3k 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
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
2k 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 ...
5
votes
3answers
14k 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
384 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
501 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
4answers
539 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
674 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
291 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
594 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
182 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
1answer
530 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
3answers
3k 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?
4
votes
2answers
1k 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' > ...
3
votes
5answers
350 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
479 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
1answer
1k 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
2answers
132 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 ...
3
votes
1answer
353 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
413 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
2k 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
120 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
63 views

What interaction is required for a Windows server and Cisco router to setup and destroy a Multicast session?

I'm trying to understand how Multicast actually works, and have read numerous articles and Wiki pages, and have gathered this: A multicast address takes up state on the router of the membership, ...
3
votes
2answers
595 views

Protocol (or service publish/discovery) to detect devices in network

we connect some embedded devices in a network. What i am looking for now, is a way to find the devices IP and identify them. We work with Windows PC´s and i am about to write a C# tool that should do ...
2
votes
4answers
249 views

Should I worry about my static IPs?

We currently have a range of 12 static IP addresses through our ISP that I believe are leased. Now that the IPv4 space is almost gone, should I be worried that our ISP (it's a Time Warner fiber ...
2
votes
2answers
120 views

IPv6 servers and IPv4 client base

As IPv4 addresses are running out rapidly, a time will come when there will not be even single IPv4 address available for allocation. But, huge number of devices will still be running on IPv4. ...
2
votes
1answer
456 views

Does Linux support IPv4 mapped IPv6 addresses?

I work in a mixed IPv4 / IPv6 environment. I read that IPv4 addresses can be mapped into the IPv6 space with this syntax ::ffff:1.2.3.4 (1.2.3.4 is the IPv4 address) Does Linux support this ...
2
votes
3answers
2k views

Are same IP address with different submask unique? [duplicate]

Possible Duplicate: How does Subnetting Work? In a same block of IPv4 addresses, can there be same IPs with different submasks? For example, can I have this: 180.70.65.140/26 ...
2
votes
2answers
86 views

Logging the outgoing port for IPV4

I need to become an IPV4 and IPV6 expert in a couple of hours. Our company is being bullied by the internet legislator in our country to move fast to offer the site in IPV6 only (we are just content ...
2
votes
1answer
1k views

How to do dual stack IPv4/IPv6 with virtual hosts on nginx 1.4

I'm using nginx 1.4.1 (now, before it was 1.2.1) and would like to support dual stack (IPv4 and IPv6). I'm always getting duplicate listen options for xyz errors from nginx. server { listen 80 ...
2
votes
1answer
2k 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?
2
votes
3answers
725 views

Server sending out packets bigger then MTU

I have a server that I am transferring data off of. We were having some problems that were traced back to the fact that the server is sending out jumbo size frames despite the fact that ifconfig is ...
2
votes
3answers
511 views

Client unable to reach Internet through OpenVPN

The clients can all connect through OpenVPN. OpenVPN serves the following pool: server 10.8.0.0 255.255.255.0 I've configured the server's iptable with the following rule: iptables -t nat -A ...
2
votes
1answer
261 views

Empty IPv6 address causes DNS error on Macs running Apache Server

For a site I manage, http://archstl.org/, the DNS entry returns an empty (::) IPv6 address when I run $ host archstl.org in the Terminal. I think the errant IPv6 entry may be the cause of my problem: ...
2
votes
2answers
253 views

OMSA only work for IPv6?

I have installed OMSA on a server and the dsm_om_connsv service is running. I have found, in the past, this always binds to an IPv6 socket only; # netstat -lnp Active Internet connections (only ...
2
votes
1answer
852 views

IPv6 fallback to IPv4

Currently I am connected to Internet over IPv4, I am using tunnel from sixxs.net and I have got subnet and one of IPv6 assigned to my eth0 interface. So, eth0 has IPv4 and IPv6: 2: eth0: ...