IP : Java Glossary

Note that IPv6 addresses are 128 bits, 16 bytes, 4 times longer than IPv4 addresses. You’d think 64 bits, allowing 18,744,073,709,551,616 addresses, or 30,77,457 addresses per person would have sufficed. However, to avoid another transition for a very long time, they went for 128 bits. This will allow simpler routing, since bands can be assigned for various regions that won’t soon fill up, and require juggling to shift slots from other regions.

A standard IPv4 (Internet Protocol Version 4) IP is written as a dotted quad e.g. 65.110.21.43 , four numbers 0..255. When entering these numbers into windows configuration dialogs, you will find it most convenient if you don’t key the dots, and zero-pad each group to three digits, e.g. 065 110 020 044. In programming, sometimes a dotted quad such as 64.251.89.39 is written as a giant 32-bit unsigned decimal number e.g. [1090214183] or in hex [40FB5927]. For example can get at my website by DNS name or by IP number with the following URLs: http://mindprod.com or http://65.110.21.43 .

Whois

1. Who owns this IP?
2. I know the domain name. What IP does it map so I can put an entry in my hosts. file.
3. Who owns this domain name?
4. Where on the planet is this IP broadcasting from?
5. What is my face IP?

1. Who Owns This IP?

• GeekTools: find owner of a given IP.
• arin.net
• whois.sc
• CyberAbuse.org: find owner given IP or DNS name.

2. Finding the IP From a Domain Name

• www.networksolutions.com/cgi-bin/whois/whois for .com, .net and .org
• www.cira.ca for .ca
• whoisreport.com for .com, .net, .org, .info, .biz and .us. This search is more flexible letting you find usaweatherreport.??? by typing just weather. The best way to figure out what all the option check boxes are for is just to tick them one at a time and see what the effect is.
• Whois Source: various TLDs, also allows lookup by IP.
• You can use TweakDUN to look up DNS names and add their ips to your host file. You can also use it to lookup up DNS names with the DNS abilities of your computer and its gateway.

3. Finding out who owns a Domain

For the third question (who owns this domain) use one of these whois services:

• Checkdomain.com. Does not make you take a typing test to use the service as many others do.
• 101Domain.com. Does not make you take a typing test to use the service as many others do.
• www.networksolutions.com/cgi-bin/whois/whois for .com, .net and .org
• www.cira.ca for .ca
• whoisreport.com for .com, .net, .org, .info, .biz and .us. This search is more flexible letting you find usaweatherreport.??? by typing just weather. The best way to figure out what all the option check boxes are for is just to tick them one at a time and see what the effect is.
• Whois Source: various TLDs, also allows lookup by IP.

4. Finding out Where a Domain/IP is Located

For third question (where is the domain located) use one of these Ip locator services:

• Discussion of kludges to get an approximate answer.
• IP Locator
• ShowMyIP.com: just tells your face IP.
• netgeo.
• Google geographical location ip address
• MaxMind sells code to obtain the country, region, city, latitude, and longitude of any IP address. This would often be an ISP rather than the actual company responsible for content.

5. Finding our Your Face IP

Ways of Finding Your Face IP
Logo	Link	Notes
	Your face IP:[38.107.191.107]	Your face IP is displayed at the bottom of every page of this website. I do this with SSI.
	IPchicken.com	tells your face ip, and which ports you have open. They also tell you your face name, e.g. your URL on the web, possibly temporarily assigned for your connection. It might look something like this S010609991195576dda.gv.shawcable.net or d207-81-138-97.bchsia.telus.net That is not my real one. I don’t want to encourage hackers.
	checkip.dyndns.org:8245/	Offers many other services as well.
	whatismyipaddress.com	has many annoying ads you must close to discover the answer.
—	—	In a Servlet you can use javax.servlet. ServletRequest. getRemotePort().

Determining your own IP Address

In JSP, the following methods may be useful: request.getServerName(), request.getServerPort() and request.getRequestURI()

If you are writing a Applet, you can find out the name of the server indirectly via Applet.getCodeBase. You have to use the URL.getHost method to pull out just the part you want.

If your webserver supports SSI you can get such information via the REMOTE_HOST (URL) REMOTE_ADDR (IP) SERVER_NAME (URL) and SERVER_ADDR (IP) directives.

In Windows, you can use the utility ipconfig /all to display information such as IP, subnet mask, DNS Server IP, host name, physical ethernet 48-bit MAC address, gateway IP and DHCP server IP. In older versions of Windows there is a similar utility called winipconfig. You can spawn this utility from Java with the exec function, and programmatically scan through the output to find what you need. Alternatively, you need to write platform specific JNI code to grab additional information, such as DNS servers, gateways, masks, etc.

There are various utilities that periodically probe to find out your IP address, then notify you if your face IP changes, and also notify the DynDns server.

Finding Out Someone Else’s IP

• InetAddress.getHostAddress to get 65.110.21.43 .
• getHostName to get www.mindprod.com.
• getCanonicalHostName to get mindprod.com.

If you are behind a firewall you may not have access to DNS or reverse DNS lookup. You might experiment by putting the DNS-IP pair in your Windows or NT HOSTS file, or working purely with IPs. Sometimes the receiver requires a DNS name, not just a pure IP. In that case you can provide one with URLConnection.setRequestProperty().

I know of no way to discover your DNS server IPs without resorting to JNI.

Unfortunately, finding out your server’s IP will trip the sandbox security mechanism in an Applet. You could sign the Applet, or you can dance around the problem this way: you get the server name from getCodeBase().getServer(), open a Socket to port 80 and retrieve the local IP address from that Socket. If getServer() returns null, the Applet is running locally, and you could just use localhost namely 127.0.0.1 as the IP address. In Linux you could use localhost@localdomain.

You can find out who owns a domain name at http://www.networksolutions.com/cgi-bin/whois/whois. Unfortunately, you can no longer find out who owns an IP. For that you need arin.net.

If you need finer control than InetAddress gives you, e.g. the ability to select the DNS server, try DNSJava.

To find out your own IP address you could lookup localhost using InetAddress. getByName but that would just give you 127.0.0.1 which is not likely what you really wanted. In Windows, you can spawn ipconfig.exe /renew and capture the IP Address line in the output.

Java maintains a cache for DNS lookup. You can control its behaviour with:

Displaying an IP

IP bit manipulation tricks

IPV6

How Are IP’s Assigned

For computers not directly attached to the Internet, (e.g. via a proxy server), or on a LAN that has Internet access, but without individual station access, or on an isolated LAN, you don’t need universally unique IP numbers. You can use the ones reserved for local private LAN use. You don’t need to get anyone’s permission to use them such as 192.168.0.1 .. 192.168.255.254

Usually a router on a home LAN is 192.168.0.1 and DHCP will assign computers on the LAN to addresses in the range 192.168.0.101… 192.168.0.110, and you assign any static IPs on the LAN in the range 192.168.0.2…192.168.0.10.

The scheme above turned out to be too limiting, so now it is largely ignored, IPs are assigned as bands of consecutive integers on any boundary. This more flexible system is called cidr — classless inter-domain routing. Because we are running out of IPs we have quadrupled their size to 128 bits with IPv6. That oughta hold 'em, 3 followed by 38 zeros of IPs to choose from.

One of the rather terrifying things about the way the Internet is designed is that there is little to stop people from configuring their machines with IPs they have no business using. It becomes trivially easy to steal unused or rarely used IPs, to spoof someone else’s identity, or to spy on someone else’s traffic. The Internet protocols were not designed to deal with malicious teenage hackers, only gentlemanly academics.

“If builders built buildings the way programmers write programs, then the first woodpecker that came along would destroy civilization.
~ Weinberg’s Second Law (born: 1933 age: 76)

How the IP Protocol Works

The IP protocol can best be understood by looking at the header that goes on each packet. The IP packet header is a bit like the baggage tag you attach to your suitcase before entrusting it to the airline:

Everything is in big endian byte order.

The sender tosses his packet of data into the Internet, with the header. Computers on the net pass the packet along hoping to get it closer and closer to its destination. Perhaps a dozen hops later it finally arrives. Perhaps it doesn’t. There is nothing in IP protocol to guarantee safe arrival. However, if a packet has to be split up for part of its journey, IP will automatically reassemble the parts.

IP protocol does not sound too promising. Unlikely you will use IP protocol directly. UDP ( via Java classes DatagramPacket and DatagramSocket) and TCP/IP (via Java classes Socket and ServerSocket) protocols are built on top of IP, and FTP and HTTP (via Java class HttpURLConnection) are built on top of TCP/IP.

Learning More

Books

	recommend book⇒Internetworking with TCP/IP Vol.1: Principles, Protocols, and Architecture, 4th edition
		hardcover
	ISBN13:	978-0-13-018380-4
	publisher:	Prentice Hall
	published:	2000-01-18
	by:	Douglas E. Comer
How IP, UDP and TCP/IP protocols work. How the domain name to IP translation DNS information in propagated.
abe books.co.uk abe books.ca amazon.co.uk amazon.ca abe books.de chapters.indigo.ca amazon.de abe books.com abe books.fr amazon.com amazon.fr barnes and noble.com abe books.it powells.com iberlibro.com sony e-books abe books anz