B1 IP Protocols Flashcards
OSI Model
1 Physical 2 Data Link 3 Network 4 Transport 5 Session 6 Presentation 7 Application
Layer 1 OSI Model
Physical - Physical structure. Hubs, repeaters, Cables,
Layer 2 OSI
Data Link - Frames (Envelopes) contain MAC address, NIc - Switch - NIC end to end) , Ethernet, WAN, Wifi,
Layer 3 OSI
Network - Packets (letter containing IP address) - Logical to physical address mapping Ipv4, IPv6, ICMP, AppleTalk
Layer 4 OSI
Transport - host to host (logical ports), TCP, UDP,
Layer 5 OSI
Session - Sync and send to ports (interhost communication) - session establishment , security, logging - TLS/SSL, NetBIOS, SOCKS
Layer 6 OSI
Presentation - syntax and encrypt and decrypt , data conversion. SSL, WEP, WPA, Kerberos
Layer 7 OSI
Application - end user layer. DHCP, DNS, FTP, HTTP, POP3, SMTP, SNMP, SSH, TELNET
Layer 1 TCP IP
Network Access or Link Layer = OSI 1 &2, Maps IP to physical address, plus forms frame and sends over network
Layer 2 TCP IP
Internet - = L3 OSI (Network). logical transmission of data using IP, ARP or ICMP
Layer 3 TCP IP
Host 2 Host / Transport. Is same as L4 OSI (Transport). Two protocols are TCP or UDP.
Layer 4 TCP IP
Application. = L5-L7 OSI. HTTP, FTP etc
IP v4 description
An IPv4 address is split into four sections, each with a number from 0-255, separated by a dot, with
sections identifying the network ID and the host ID. How many bits are used for the network portion will
vary from network to network. 4 billion possible addresses. 32 bit - 8 bits per section (octet).
Subnet basics
A subnet mask is a 32 bit number for IPv4, or a 128 bit number for IPv6, that divides the IP address into
network and host addresses.
Subnet mask
A Subnet Mask is made by setting network bits to all “1”s and setting host bits to all “0”s.
Subnet example
For example take a network 214.129.7.0/24. The 24 in the CIDR notation tells you the network mask is 24
bits long, and so it is. 255.255.255.0 where each 255 is all 8 bits of the octet set to binary 1. The broadcast
address for this network would be 214.129.7.255
Class A Public IP
0.0.0.0 - 126.255.255.255
Class A Private IP
10.0.0.0 - 10.255.255.255
Loopback
127.0.0.1 but also 127.0.0.0/8 so up to 127.255.255.255
Class B Public IP
128.0.0.0 - 191.255.255.255
Class B Private IP
172.16.0.0 - 172.31.255.255
Class C Public IP
192.0.0.0 - 223.255.255.255
Class C Private IP
192.168.0.0 - 192.168.255.255 - Lots of domestic networks
Class D Public IP
224.0.0.0 - 239.255.255.255
Class E Public IP
240.0.0.0 - 255.255.255.255
IPv6
An IPv6 address is split into eight sections, each separated by a colon, as shown in the slide. Each section consists 16 bits, written as four hexadecimal digits. To make them shorter to write down, multiple sections which are all 0 can be replaced by a double colon :: as you can see in the example, but this can only
happen with one run of 0000’s. If an IPv6 address contains more than one sequence of repeating 0000’s,
only one of them can be replaced by the :: sequence
Categories of Ipv6 address
UNicast
Multicast
Anycast
5 types of network addressing
Unicast - 1 to 1
Broadcast 1 to all
Multicast one to many or many to many
Geocast -special form of multicast based on physical location
Anycast - one to one of many (ie which is nearest receiver in the group that the message needs to go to)
3 uses of ICMP
error reporting and diagnosis
help solve nwtwork problems
denial of service attack
3 way handshake to establish TCP session
SYN(chronise)
SYN/ACK(nowledge)
ACK
3 features of TCP (Transmission Control protocol)
Data divided into packets
Checksums ensure data is not corrupted
Sequence numbers detect loss and rebuild data in correct order
Features of UDP (User Datagram protocol)
Faster transmission that TCP No error detection No sequencing or tracking No guarentee that packet will arrive used for online gaming, media streaming and VoIP
4 stages of DHCP
DORA Discovery Offer Request Acknowledgement
Configurations provided by DHCP server
IP (usually dynamic)
subnet mask
default gateway
name servers
FTP ports
20 data
21 control
Reason FTP is not used much
sends all data including user password in the clear
Secure versions of FTP
FTPS (uses SSL/TLS)
SFTP (uses SSH)
Server Message Block (SMB)
Share files and folders
Uses port 445 TCP and UDP
Implementations of SMB on different OS
CIFS - Windows
Samba - Linux
Simple Network Management Protocol (SNMP) purpose
Protocol to monitor, audit and manage devices connected to a network.
SNMP ports
UDP 161