Ethical Hacking simplified. IP version 6 (System fundamentals)

IPv6

IPv4 address contains less than five billion addresses. With the technological advancement IPv4 cannot is almost if not already outnumbered. Here comes the BOOM! IPv6! It comes with an unlimited addresses which if it every human, animals trees impact anything you can think of is given address in cannot be outnumbered! Yeah!! anything including the human/hair grain of sand! Stop thinking you heard me right! IPv6 solved any problem regarding addressing system shortages. Although it comes with many upgrades, impact is an overhaul of IPv4. IPv4 is divided into 4 parts, while IPv6 is divided into 8 parts!

Example 2001:0df9:4cd7:0011:0000:0000:3541:35da

The first three are the global prefix, followed by the subnet and the last four are the interface. Ohh I thought technological advancement is to make things easier not complicated! Laughing.... don't worry IPv6 is easier than IPv4. Whats easy here! A chunk of letters and numbers all together? Hmmm... don't forget that that those letters you see are hexadecimal! Since IPv6 uses 16bits to represent itself! You can again call it a 16bit hexadecimal colon-delimited blocks! And you said its simple?

When trying to test a network built on IPv6, the address has to be inside an angle bracket. Why? In every browser the colon which is part of IPv6 is already assigned to port numbers (don't worry we will talk about this later).

Example http://[2001:0df9:4cd7:0011:0000:0000:3541:35da]/index.html

Shortening IPv6

One of the good things about this new bride is it can be shortened. You don't need to be always writing the full address always, there are some part of the address that can abbreviated thus reducing its length. Example instead of writing 2001:0df9:4cd7:0011:0000:0000:3541:35da or can write 2001:df9:4cd7:11:0:0:3541:35da or 2001:df9:4cd7:11::3541:35da. You can always short write where there is 0 in your address, if all the four digits are 0s, you can choose to write one 0 or no just an empty space like the above example. But you should know that if four zeros comes in more than two colon, you cant represent them all with colons. Example 2001:0000:0000:adf1:0000:0000:3541:35da you cannot shortened this address like this 2001::adf1::3541:35da because the router will be drunk! It wont know from where to start placing the 0. Instead you should apply all the two shortening tricks, it should be like this: 2001:0:0:adf1::3541:35da. Put that into your bread laughs your brain!

Addressing type

IPv6 as I already said is an overhaul of the IPv4, in IPv4 we only have global address (the ones that can go onto the internet) and private address (the ones that cant go on the internet). Again we have transmission types (multicast, unicast and broadcast, refer to IP addressing I have update it). In IPv6 its all combined into addressing type. Lets go and see the new approach........

Unicast Almost same with the IPv4, Unicast address sent packet directly to one interface. But in IPv6 unicast is divided into many subgroups.

1. Aggregatable global unicast address
2. Link-local address
3. Site-local address
4. Special address
5. Compatibility address
6. NSAP address

Aggregatable unicast addresses: This is the same thing with the IPv4 global or public IP addresses because it can go on to the internet, it can be routed and reached on the internetwork just like the normal IPv4 global addresses.

Link-local addresses: As the name already explained, this type of unicast address is used to test local neighbor device or host. It is used in network discovery discovering a near by device connected on the same link. When two devices are directly connected with no router, they use this address automatically to communicate.

Site-local addresses: This are the same with normal IPv4 private addresses, the only difference is this addresses cannot be forwarded by routers. They always remains local within the site they are configured.

Special addresses

• Unspecified addresses: This address is used to show an absent of an address. This address is used for a packet to test and verify the uniqueness of doubtful addresses this is the same with IPv4 0.0.0.0. This address is never assigned to any interface. The unspecified address is 0:0:0:0:0:0:0:0 0r ::
• Loopback address: This address is used to test a loopback packet, this is the same 127.0.0.0 in IPv4, it allows the device to test itself by sending packet to itself. The loopback address is 0:0:0:0:0:0:0:1 or ::1.

Compatibility addresses: This is used to easily migrate from IPv4 to IPv6. It aid in running a IPv4 network on IPv6. Take for example, running a windows XP program on windows 8.1, you need to go through some compatibility steps to create windows XP compatible environment for the program.

• IPv4 compatible addresses: This uses 0:0:0:0:0:0:a.b.c.d or ::a.b.c.d(where a.b.c.d is an IPv4 global address). This method is used by dual-stack nodes that are communicating IPv6 over IPv4 networks. Dual-stack nodes are are nodes which has the IPv4 and IPv6 protocols. When IPv4 address is used as IPv6 destination, it automatically encapsulates the packet with IPv4 header and send it the destination using IPv4 networking resources.
• IPv4 mapped address: this is used to represent an IPv4 device to IPv6, this is only for internal representation within the device. Mapped addresses cannot be source nor destination address on any network. It is represented in this way 0:0:0:0:0:FFFF:a.b.c.d or ::FFFF:a.b.c.d.
• IPv6 to IPv4 address(6 to 4): This address is used to communicate between devices running both v4 and v6 using the internet. This type of address is formed by adding up 2002::/16 with the 32bits of public IPv4 address, which will form 42bits prefix.

NSAP addresses: This is created to provide a means for mapping Network Service Access Point(NSAP) to IPv6 addresses.

Multicast: This is the same with IPv4 where some nodes or devices will be selected and send packet to them at the same time. It is one to many transmission not one to all, IPv6 doesn't support broadcast. It is simple to recognize a multicast address because it always starts with FF.

Anycast: This is almost the same with multicast and at the same time with unicast! Confused? My reasons are, when sending packet using anycast you identify many devices but only one device can get it and that is the first device out of the list. For example you send someone to your house, you tell him if you see my wife, my brother or sister give the package to him/her. When sending the package you mention many names but only the first contact will collect it!

Unique local address: This addresses are not allowed on the internet, but they are allowed to be used on routers contrary to the site-local addresses. They are exactly the public addresses we have in IPv4. The site-local address was discontinued(dropped) in September 2004. The unique local address range is represented FC00::/7.

Reserved addresses for documentation: 

3FFF:FFFF::/32 and 2001:0DB8::/32

tobe continued....