Networks_IP-nets_2

AGENDA
IP-Addressing
IPv4
Tools
IP-Networks
NAT
VPN

ADDRESSING

IP ADDRESS

IPv4
IP-Address – unique logical address of 3rd level
Contained at the header of IP-package and identify the following:
Sender – Source Address (32)
Receiver – Destination Address (32)
IPv4 length – 32 bits
Form: decimal format with dots by octets ? 4 octets

IPv4 components
Network part of address – high bits
P – the number of bits
Define the maximum number of networks
The part of device address (Host Part) – lower bits
N – the number of bits
Define the maximum number of hosts in the network
P + N = 32

IPv4 Address types
Host Address
unambiguously identify one network device ( 192.168.25.[1-254] )
Network Address
Identify all subnet
All bits of the Host part are zero
Using for routing ( 192.168.25.0 )
Broadcast Address
Specify all devices on a subnet
All Host part bits are one
Used to broadcast to all devices on the same network ( 192.168.25.255 )

PREFIX
PREFIX Length – number of bits of network part of whole address
Unambiguously identify:
Maximum number of devices in the network 2N - 2
Maximum number of networks (current level) 2Prefix_Length
Addresses
Network
Broadcast
N = 32 – PREFIX_Length

PREFIXES

TYPE OF TRANSMISSION
Unicast – individual transmission
Addressed to a single device (the only one)
Broadcast
Addressed to all devices
Directed Broadcast – in remote subnet
Limited Broadcast – in local subnet
Multicast
The sender sends data to a group of
addresses (several)

UNICAST
Addressee:
One – separate device
Defined in the filed of IPv4 header (device)
Destination Address – logical address of the device

BROADCAST
Addressee
All devices in defined subnet
Local LAN (Limited Broadcast)
Remote LAN (Directed Broadcast)
Defined in the field of IPv4 header (subnet):
Destination Address – broadcast address of subnet

MULTICAST
Addressee:
Selected group of devices
Defined in the filed of IPv4 header
Destination Address – separate reserved group

IPv4 Host Addresses

IPv4 Host Addresses

IPv4 Host Addresses
Private
Class A: 10.0.0.0/8
Class B: 172.16.0.0/12
Class C: 192.168.0.0/16

SPECIAL ADDRESSES
Network Addresses
Broadcast Addresses
Default Route
0.0.0.0
Reserved: 0.0.0.0/8
Loopback Address
127.0.0.1
Reserved: 127.0.0.0/8
Link-Local Addresses
169.254.0.0/16
TEST-NET Addresses
192.0.2.0/24

SUBNET MASK
Subnet mask – 32-bit number which show range of IP-addresses that located in one subnet
1 – subnet bits (inseparable, from left to right)
0 – device bits (inseparable, from right to left)
A subnet mask is a 32-bit number created by setting host bits to all 0s and setting network bits to all 1s.
In this way, the subnet mask separates the IP address into the network and host addresses.

SUBNET MASK

SUBNETTING
Subnetting (dividing on subnets) – creating logical subnets from one block of addresses (network)
Borrowing bits into the network part of the address (S bit)
Number of subnets 2s
Maximum number of devices in the network 2N - 2

SUBNETTING
Advantages
Simplified management
Simplification of addressing
Simplification of routing
Minimizing network load
(traffic localization)
Criteria
Geographic location
Appointment
Responsibility (property)

IPv6
An IPv6 protocol address consists of 128 bits
xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx
each letter x is a hexadecimal digit representing 4 bits
Part of the bits on the left (depending on the prefix) indicate the network, the remaining bits on the right identify the device
IPv6 does not use subnet masks as they would be very long, instead a prefix is used
The /64 prefix means the first 64 is the network and the rest is the host.

IPv6
To shorten an address, rules must be applied in succession.
2001:0DB0:0000:123A:0000:0000:0000:0030
Leading zeros are removed;
If the hextet consists of only zeros, then it is replaced by one zero
2001:DB0:0:123A:0:0:0:30
One longest group is selected, consisting of completely zero hextetsthe longest sequence is ":0:0:0:" and is replaced by two colons "::"
2001:DB0:0:123A::30

IPv6. Loopback
Used to send a packet to itself
127.0.0.1
There is only one cyclic address
0000:0000:0000:0000:0000:0000:0000:0001
short version
::1
The corresponding virtual physical interface is named LOOPBACK.

NETWORK TOOLS

NETWORK TEST (LOOPBACK)
Ping – utility for testing IP-connection
ICMP – Internet Control Message Protocol
ICMP Echo Request
ICMP Echo Reply
Testing local stack TCP/IP (127.0.0.1 – Loopback)
Reflect the state of the network layer (local)
Doesn’t say anything about the underlying levels
Doesn’t say anything about the correctness of the network settings (IP, Mask, Gateway, …)

NETWORK TEST (LOCAL)
Testing local network (IP, Gateway)
Checking workability of gateway
Functioning of whole stack TCP/IP
Functioning of Hub/Switch
Functioning of LAN

NETWORK TEST (REMOTE)
Testing connections with remote network (device)
Gateway capability (WAN, Internet)
Functioning of intermediate equipment (and software)
Functioning of final addressable device (and software)
Restrictions
Gateway capability (WAN, Internet)
Prohibition / Rejection ICMP datagrams
Difficulty of routes

TESTING ROUTE
Traceroute (in windows ? tracert) – utility for showing the path
ICMP
Echo Request
Time Exceeded
Displaying the path (s) of packages
Display network delay time (round trip time)

TESTING ROUTE

TESTING ROUTE
Local router. The first lines of the traceroute results will indicate your gateway’s IP address.
PoP router. A Point of Presence (PoP) is the local access point of your ISP. This access point helps your device establish a connection with the internet.
Source Tier 2 ISP Network. Your request might be routed to a regional ISP (like Comcast or Cox), which services a limited geographic area.
IXP. An Internet Exchange Point (IXP) is a physical location where ISPs and other network providers connect to exchange internet traffic.
Tier 1 ISP Network. These ISP providers are considered the backbone of the internet because they own the infrastructure to carry most of the traffic themselves.

IP-NETWORK
TECHNOLOGIES

IP-NETWORK TECHNOLOGIES
Network Address Translation (NAT)
Demilitarized zone (DMZ)
Virtual Private Network (VPN)

NETWORK ADDRESS TRANSLATION
Network Address Translation (NAT) – technology of address translation
Rewriting IP addresses and ports as the packet passes through intermediate network device
Address Translation Concepts
Static NAT
Dynamic NAT
Masquerading
Types:
Source NAT (SNAT)
Destination NAT (DNAT)
Port Address Translation (PAT)

TYPES & CONCEPTION NAT [1]
Source NAT (SNAT):
Providing access from a local network (private, private, closed) to the Internet (public network)
The request is initiated from the internal network
Destination NAT (DNAT):
Providing access from the Internet to the local network
The request is initiated from the external network
The request is forwarded to a specific internal host
Port Address Translation (PAT):
Associates the public address and port with the internal address and port (access to internal services from the outside)
Often called "port forwarding"

TYPES & CONCEPTION NAT [2]
Static NAT:
Links one private address to one public address
Dynamic NAT:
Associates many private addresses with a pool of public ones
Masquerading:
Subtype of Source NAT
The external address is not explicitly indicated, but determined automatically (for the specified interface)
Used for dynamic "white" addresses

PORT ADDRESS TRANSLATION (PAT)
Port Address Translation (PAT), this is where each client uses the same IP address but uses a different port.
A good example is access to a web server. Users from a private address, say in the 10.0.0.0 network, have their individual addresses translated to just one legal IP address but separate port numbers between 1024 and 65535.
They can all have separate conversations with a web server having just one address and destination port of 80 (HTTP).
This applies just as well if one user has several sessions with the same web server, the different port numbers distinguish the sessions.

PAT

NAT: ADVANTAGES / DISADVANTAGES

VIRTUAL PRIVATE NETWORK (VPN)
Virtual Private Network (VPN) – network built on top of another network
Typically, the underlying network is public (untrusted)
VPN Building Options:
Intranet VPN – Integration into a single secure network several distributed networks of one organization (interaction through open channels)
Remote Access VPN – secure communication between corporate network segment and single user
Client / Server VPN – protection of transmitted data between two nodes (not networks) of the corporate network; authorized access to certain resources

VPN: ADVANTAGES / DISADVANTAGES

TERMS and ABBREVIATIONS
IPv4
Reserved Addresses
Unicast
Broadcast
Multicast
NAT
NAT: PAT
Subnet mask
Subnetting
Ping
Traceroute
VPN

REFERENCES & SOURCES
https://www.ietf.org/rfc/rfc1631.txt – NAT