Originally the datagram service for TCP, the Internet Protocol now transfers many different higher level protocols. The Internet Protocol has two main functions
Addressing
The addressing function examines the address on the incoming packet and decides if the datagram (packet) is for the local system or for another system. If the address indicates the datagram is for the local system, the headers are removed and the datagram is passed up to the next layer in the protocol stack. If the address indicates the datagram is for another machine, then it is passed to the next system in the direction of the final destination.
Fragmentation
The fragmentation component will split and re-assemble the packets if the path to the next system uses a smaller transmission unit size.
Addressing
The addressing function examines the address on the incoming packet and decides if the datagram (packet) is for the local system or for another system. If the address indicates the datagram is for the local system, the headers are removed and the datagram is passed up to the next layer in the protocol stack. If the address indicates the datagram is for another machine, then it is passed to the next system in the direction of the final destination.
Fragmentation
The fragmentation component will split and re-assemble the packets if the path to the next system uses a smaller transmission unit size.
OSI Layer 2: Data Link Layer
The Data Link Layer deals with transferring data between network nodes:
Adjacent nodes in a Wide Area Network (WAN)
Nodes on the same Local Area Network (LAN) segment.
Some of the common Data Link Layer protocols are:
Ethernet
ARP: Address Resolution Protocol
PPP: Point to Point Protocol
STP: Spanning Tree Protocol.
The Data Link Layer deals with transferring data between network nodes:
Adjacent nodes in a Wide Area Network (WAN)
Nodes on the same Local Area Network (LAN) segment.
Some of the common Data Link Layer protocols are:
Ethernet
ARP: Address Resolution Protocol
PPP: Point to Point Protocol
STP: Spanning Tree Protocol.
OSI Layer 1: Physical Layer
The Physical Layer is the lowest possible layer and deals with the actual physical transfer of information. This layer deals with transferring bits over a physical medium:
Electric pulses over copper cables
Laser pulses over fiber optic cables
Frequency modulations over radio waves
Scraps of paper over carrier pigeons (to learn more, review the following memo: A Standard for the Transmission of IP Datagrams on Avian Carriers).
There are various different protocols, hardware types, and standards defined for different types of physical networks (commonly referred to as PHYs):
IEEE 802.3: Copper or fiber connections
IEEE 802.11: Wireless (Wi-Fi) connections
Bluetooth: Wireless connections
USB: Copper connections
RS232: Copper serial connections.
The Physical Layer is the lowest possible layer and deals with the actual physical transfer of information. This layer deals with transferring bits over a physical medium:
Electric pulses over copper cables
Laser pulses over fiber optic cables
Frequency modulations over radio waves
Scraps of paper over carrier pigeons (to learn more, review the following memo: A Standard for the Transmission of IP Datagrams on Avian Carriers).
There are various different protocols, hardware types, and standards defined for different types of physical networks (commonly referred to as PHYs):
IEEE 802.3: Copper or fiber connections
IEEE 802.11: Wireless (Wi-Fi) connections
Bluetooth: Wireless connections
USB: Copper connections
RS232: Copper serial connections.
Security Awareness
Awareness is one of the best ways to combat insecurity. Security-related mailing lists like Common Vulnerabilities and Exposures (CVE) and The United States Computer Emergency Readiness Team (US-CERT) alerts help to inform system and network administrators of currently known vulnerabilities.
It also helps to think like a bad guy. You should have a non-production lab you attempt to break into, do security drills, and use resources like the "2600 Magazine: The Hacker Quarterly" to see how someone could infiltrate your network.
Distribution errata is another security concern.
You should never underestimate the power of human nature. Be aware of phishing scams or other types of social engineering attacks. You should continuously train your users on how to avoid falling prey to these attacks. You should always be aware of the layer 8 (human) errors.
Awareness is one of the best ways to combat insecurity. Security-related mailing lists like Common Vulnerabilities and Exposures (CVE) and The United States Computer Emergency Readiness Team (US-CERT) alerts help to inform system and network administrators of currently known vulnerabilities.
It also helps to think like a bad guy. You should have a non-production lab you attempt to break into, do security drills, and use resources like the "2600 Magazine: The Hacker Quarterly" to see how someone could infiltrate your network.
Distribution errata is another security concern.
You should never underestimate the power of human nature. Be aware of phishing scams or other types of social engineering attacks. You should continuously train your users on how to avoid falling prey to these attacks. You should always be aware of the layer 8 (human) errors.
The following image depicts the conceptual networking components involved when running a VM on a computer then launching a LXC container on that VM.
Be aware that many details have been omitted and would be required to make this a functioning example.
The real machine is connected to an ISP providing DHCP services assigning our adapter an address of 192.168.0.187.
The real machine is using KVM and deployed libvirtd which provides dhcp services in the subnet of 192.168.122.0 on the devices connected to Virt-bridge-1.
Our Virtual Machine is connected to Virt-Bridge-1 via the virtual adapter Virt-NIC-1 and is assigned an IP Address of 192.168.122.223.
Additionally, the Virtual-Machine has a dhcp server provided by its instance of libvirt. The default address of 192.168.122.1 for the dhcp server on Virtual-Machine has to be altered to avoid conflicts with the dhcp server running on the real machine. In this example the dhcp server on the Virtual-Machine was moved to the subnet 192.168.124.0.
Be aware that many details have been omitted and would be required to make this a functioning example.
The real machine is connected to an ISP providing DHCP services assigning our adapter an address of 192.168.0.187.
The real machine is using KVM and deployed libvirtd which provides dhcp services in the subnet of 192.168.122.0 on the devices connected to Virt-bridge-1.
Our Virtual Machine is connected to Virt-Bridge-1 via the virtual adapter Virt-NIC-1 and is assigned an IP Address of 192.168.122.223.
Additionally, the Virtual-Machine has a dhcp server provided by its instance of libvirt. The default address of 192.168.122.1 for the dhcp server on Virtual-Machine has to be altered to avoid conflicts with the dhcp server running on the real machine. In this example the dhcp server on the Virtual-Machine was moved to the subnet 192.168.124.0.
A second virtual bridge, Virt-Bridge-2 and virtual adapter Virt-NIC-2 were created on Virtual-Machine by libvirtd.
The lxc-container default configuration looks for the bridge by name. The libvirtd generated bridge is usually called virbr0. In this example the lxc default bridge was changed from lxbr0 to virbr0.
The LXC-container will receive an IP Address from the dhcp server on the Virtual-Machine. In this example the address is: 192.168.142.223.
The lxc-container default configuration looks for the bridge by name. The libvirtd generated bridge is usually called virbr0. In this example the lxc default bridge was changed from lxbr0 to virbr0.
The LXC-container will receive an IP Address from the dhcp server on the Virtual-Machine. In this example the address is: 192.168.142.223.
“The Complete DevOps RoadMap” by javinpaul https://link.medium.com/12gReCGrcab
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