Install and configure the following networking services applications - Paiet/Tech-Journal-for-Everything GitHub Wiki
Install and configure the following networking services/applications
DHCP (Dynamic Host Configuration Protocol)
Static vs dynamic IP addressing
Static addressing
Manually configured
Configuration doesn't change without admin interaction
Static addressing is usually employed for systems with dedicated functions
Servers
Router
Printer
Dynamic addressing
Configured by requesting IP information from a DHCP server
DHCP server "leases" IP address to requesting client
Client will need to request a new lease when the current lease expires or is released
Reservations
Certain IP addresses that need to be set aside for a specific host
Hosts are specified by their MAC address
Using DHCP reduces the complexity and extent of administration in contrast to that of setting the IP addresses and configuration statically
Scopes
IP Address ranges that are authorized by the DHCP server for leasing to requesting DHCP clients
Leases
Consists of the IP address and other IP info (gateway, DNS, subnet mask)
Lease process
Discovery: Host broadcasts a request to the network using DHCP Discover to 255.255.255.255 looking for active DHCP servers
Offer: DHCP servers that receive the broadcast Discover request will respond directly to the requesting host with an Offer packet that contains a usable IP address
Request: Host accepts the IP address and requests to lease it from the server.
Acknowledge: Server acknowledges the lease request using a DHCP ACK. The ACK contains the IP Address and settings, as well as the lease time. Server then flags that IP address as in use.
Options (DNS servers, suffixes)
Other pieces of IP information other than the IP address
Subnet Mask
Gateway
DNS server info
Options are applied to all clients that request IP info from the server
Reduces administration time and effort through automation
Categories
Global options: Applies to all DHCP servers and their clients
Scope options: Applies to clients that get their lease from a specific scope
Class options: For clients that request a particular class during lease request
Reserved Client options: Applies to clients with an address reservation
IP helper/DHCP relay
Enables DHCP broadcasts to be sent to different subnets
Sends the broadcast out as a unicast transmission
Usually a router
Sometimes a layer 3 switch
Regardless of the device, it must be RFC 1542 compliant
IP Helper
API used by C/C++ programmers to retrieve and configure network info
Used to forward DHCP broadcasts
After the IP Helper relays the IP address to the requesting client the client can then contact the DHCP server directly even though it isn't on the same subnet
It can do this because it no longer needs to broadcast requests, but now has the servers direct route from its IP address
DNS (Domain Name System)
Translates Fully Qualified Domain Names (FQDN) into IP addresses
Internal vs. External DNS servers
Internal servers keep DNS records for their organization and its hosts
External servers keep DNS records for registered domains on the internet
Hierarchical system
Starts at the top with "." which is the root level
All other levels are under the root level
Next is the "Top Level" domains
.com .net .org .edu .gov
Then "First Level" domains
This will be your registered domain name
i.e microsoft.com, ufl.edu, whitehouse.gov
"Child" domains or "sub-domains"
i.e. shands.ufl.edu
Finally Fully Qualified Domain Names
pc1.shands.ufl.edu
DNS servers
Provide service for hosts that are requesting DNS information
Types of DNS servers
Default DNS server
Authoritative Name Server (ANS)
Start of Authority (SOA)
DNS records (A, MX, AAAA, CNAME, PTR)
A Record: Maps a host name to its 32bit IPv4 address
AAAA Record: Maps a host n ame to its 128bit IPv6 address
CNAME: Canonical name. Maps multiple canonical names to an A record. Also called a DNS alias.
MX: Mail Exchanger. Maps a domain name to an email server list
PTR: Pointer record. Maps IP address to host names. Also call reverse lookup.
Dynamic DNS
The ability of a host to add a DNS record and change it dynamically
This is especially helpful for DHCP clients
Every time the host acquires a new IP address it can update its DNS record
Install and configure the following networking services/applications Pt2
Proxy/reverse proxy
Proxy servers both request and store content on behalf of a requesting host to protect the host
Forward Proxy server
The proxy checks to see if it has the requested content in its local cache
If so, it delivers that content to the requesting host
If not, it looks at the requester's packet content then generates a new request itself and sends that to the intended destination
This makes destination host think that the original source host is the proxy server, hiding the real source host info
Reverse Proxy server
Instead of proxying outbound requests a reverse proxy handles inbound requests
This is done to protect servers from outside attack
Also allows for load balancing
Web Proxy server
Proxy server that is used for providing anonymous access to web content
NAT (Network Address Translation)
Allows hosts with a private IP address to utilize a public IP address to access the internet or other networks with the same private IP scheme
SNAT
Debated meaning
Static NAT (Cisco)
Secure NAT
Stateful NAT
Source NAT
2 or more routers working in conjunction to perform NAT
Creates a hard wired mapping from a private IP to a registered public IP
DNAT
Dynamic NAT
Pulls from a pool of IP addresses instead of mapping to one specific IP address
Mapping is done dynamically
Each host IP still needs a 1-to-1 mapping with a registered public IP
PAT
Port Address Translation
Also called "overloading"
Maps an internal IP address to a routable external IP address and a free port number
By utilizing a port number, only one public IP address is needed instead of one per host
Port forwarding
Creates a permanent NAT entry that maps a protocol port on a gateway to an IP address and port on a private LAN
This allows for hosts that reside on a private LAN to be accessed from the internet