IP address is a numerical label assigned to each device participating in a computer network that uses IP for communication.

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48
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15answers
7k views

Are IP addresses “trivial to forge”?

I was reading through some of the notes on Google's new public DNS service: Performance Benefits Security Benefits I noticed under the security section this paragraph: Until a standard ...
58
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4answers
59k views

What's the difference between ip address 0.0.0.0 and 127.0.0.1?

I do know that 127.0.0.1 ~ 127.255.255.254 are the loopback IP addresses for most modern operating systems and we could use these IP addresses to refer to our own computer. But what's 0.0.0.0? It ...
1
vote
1answer
789 views

Reverse DNS Lookup from the Command Line

I'd like to get a list of all domains pointed to a certain IP address. Is there a way to get this information from the command line? Nothing like "host", "nslookup" or "dig -x". Those return the ...
2
votes
2answers
1k views

BGP Multihomed/Multi-location best practice

We're in the process of designing a new iteration of our network where we improve resilliency by adding a second datacentre. We'll be adding a second datacentre, with an identical configuration of ...
10
votes
4answers
14k views

multiple MAC addresses on one physical network interface (linux)

Simple question: How can I setup multiple MAC addresses on one physical network interface (linux)? Why? My ISP is checking ip<->mac on GW and I d like to route traffic through my "linuxbox" and ...
6
votes
3answers
6k views

How can I do traffic shaping in Linux by IP?

We have a transparent proxy setup. I tried looking for traffic shaping in Linux, and all I could find online was to limit traffic by interface (eth0/eth1...). I need to limit the bandwidth (never ...
17
votes
4answers
11k views

How does a computer obtain an IP address via DHCP?

How does the computer know which device on the network to query? How does the default gateway factor into this? Pretty much, what is the chain of events that occurs when a computer tries to obtain an ...
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 ...
6
votes
7answers
11k views

How do you have one IP address and many websites?

How can I have it where I have one IP address that sits on the Internet but many web names? For example, when a hosting company has a shared IP but I get unlimited domain names (along with everyone ...
7
votes
4answers
746 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 ...
6
votes
2answers
2k views

DMZ subnet: to NAT or not to NAT?

I'm looking at setting up a DMZ behind a Cisco ASA that will contain a large number of HTTP front-end load balancers and SSL offload services - over 100 IPs, concentrated on a smaller number of hosts. ...
5
votes
7answers
4k views

Static IP Address assignment vs DHCP address assignment

I manage a small-ish network that consists of less than 70 nodes. The previous system administrators opted to have a dhcp server and manually set dhcp addess. I have opted to rather use dhcp ...
7
votes
3answers
3k views

Is there an “official” name to the 0.0.0.0 IP address?

As 127.0.0.1 is known as the loopback address, is there a shorter term to refer to 0.0.0.0 other than "the IP address who means all IP address on local machine"?
6
votes
6answers
3k views

How can I find out who is hosting a certain domain? [duplicate]

I've got a friend who has been completely abandoned by his previous website guy. Yes, the guy was cut rate, and yes, you get what you pay for. Anyway, he has asked me to help him untangle all that ...
11
votes
5answers
487 views

Understand IP addresses and location

I risk posing an ill formed question here, but I'll give it a whirl. Does it generally stand to reason that the nearer IP address A is to IP address B numerically, then the nearer IP address A is ...
11
votes
16answers
32k views

Shell Command for Getting IP Address?

Is there a bash command to find the IP address for an Ubuntu box? I need to find the IP address so I can ssh into the machine later.
4
votes
1answer
2k views

How are IP addresses assigned? What do the parts mean? [duplicate]

Possible Duplicate: How does Subnetting Work? IP addresses and geographical locations How does my IP address get assigned to me? Is there any ordering? For instance by time or by location ...
4
votes
2answers
22k views

How does 3G/Mobile phones get allocated an IP address? Does this mess with Google Analytics?

This question is in two parts. Q1. How does a mobile phone get an IP address over 3G? Like, would it get the same IP for a shortish period of time (Eg. 1 day, etc)? Because my phone is constantly ...
3
votes
1answer
12k views

How are cellphone IP addresses assigned?

When my cellphone accesses a website via the tower and its GPRS gateway, NAT ensures that the sites receive a public IP. Would all phones using a single tower have the same IP? If yes, then how can ...
2
votes
1answer
394 views

Managed switch port-based DHCP allocation - general case?

I saw a strange comment bagging IT departments (i.e. sysadmins) on Slashdot the other day: half the time they cant even do a simple thing like provide a jack with a set IP address for us Reading ...
1
vote
2answers
489 views

Static IP for dynamic IP

I have a dynamic IP address. I would like to have a static IP, but Virgin Media don't allow static IPs for residential broadband services, even if you ask them really nicely and offer to pay for it ...
0
votes
1answer
294 views

Virtual pfSense Appliance on VMWare Host

I am having some issues setting up the WAN side of pfSense. I have ordered a dedicated box through a hosting service with ESXi loaded on it. Along with that I have 3 public IP addresses that will ...
0
votes
1answer
91 views

One-liner to retrieve external IP address [duplicate]

Possible Duplicate: Finding the Public IP address in a shell script For use in scripting, it would be handy to be able to do this: IP=`....something ....` echo ...$IP... >> ...
0
votes
1answer
487 views

Multiple internal IP's running on one external IP?

My ISP has given me 1 static IP address, however, I need to run multiple internal IP addresses (from VPS's) under that 1 public IP address. I have enough network connections to my router, but not ...
-1
votes
2answers
2k views

DNS simulation for testing purposes?

I'm wishing to simulate DNS for testing purposes, having decided to learn about it for if I was to go into webhosting. I've considered BIND (and tried setting it up), but that wasn't suited to my ...