📚 IP

This article is about IP protocol (v4, v6 and IPX).

IPv4

Number on top and along the left edge are bits (not bytes). The addresses itselves are 32 bits long.

Reserved Addresses

10.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255

Fragmentation

Data Transmission Types

Unicast

Only one host can receive and read a message. Other PCs will discard it (unless in a promiscuous mode or on a hub).

Multicast

It’s very similar a subscription or a chat group. You’ll receive a message only if you have a specific address. A host can choose whether it can or cannot receive it.

Multicasting is happening both on the data link (MAC addresses) and network (IP addresses) levels. For hwardware multicating (MAC addresses) refer to the data link layer page.

A device (may be a PC) detects a multicast frame (by MAC address), verifies it and sends it further to layer 3 (assuming it’s its group). This type of communication is used a lot between routers, for example, OSPF protocol.

✍️ To map hardware multicast to an IP multicast place the low order 23 bits of the IP multicast addresss into the low-order 23 bits of the special Ethernet multicast address. The rest of the high-order bits are defined by the IEEE.

Examples of IP multicast addresses: 224.0.0.0 - base address, 224.0.0.1 - all systems on this subnet. 224.0.0.2 - all routers on the subnet. 224.0.0.4 - DVMRP Routers. 224.0.0.5 OSPFIGP All routers.

Broadcast

No matter what the host wants, it’ll receive the message (like a draft card).

This one is much easier to explain. There are two addresses in regards of broadcasting. MAC: FF:FF:FF:FF:FF:FF, IP: 255.255.255.255. Subnet broadcast might be a little confuding though. How does it differ from multicasting?

Picture

Protocols using multicast/broadcast: ARP, OSPF (routing), RIP1 (routing), SAP (locate printer), RIP (routing), NLSP (Netware link server), AARP (AppleTalk)

Classes

Class A: 0.0.0.0 - 125.255.255.255

Class B: 128.0.0.0 - 191.255.255.255

Class C: 192.0.0.0 - 223.255.255.255

Class D: 224.0.0.0 - 239.255.255.255

Class C: 240.0.0.0 - 255.255.255.255

Subnetting

NAT

Static, dynamic and … hybrid? No, Overload. Yuck 🤮!

IPv6

Addresses are 4 times bigger than that of the IPv4: 128 bits each. However, overall it’s more compact and has built-in IPsec support.

Data Transmission Types

Unicast

Multicast

Extensions

Attacks

mitm6. LDAPS?

ntlmrelayx.py -6 -t ldaps://<IP> -wh fake.domail.local -l lootme

https://dirkjanm.io/worst-of-both-worlds-ntlm-relaying-and-kerberos-delegation/

Autoconfig (IPv6)

ICMPTX

IP over ICMP

References

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