Computer Network Workshop 2022 PDF

ITI Introduction to Computer Networks & Cyber Security Prepared By : Mohamed AboSehly  Agenda ❖ Session 1 Network Essentials ❖ Session 2 Cyber Security Essentials ❖ Session 3 Distributed System  Computer Network Workshop References: o Essential Computer Sci...

ITI Introduction to Computer Networks & Cyber Security Prepared By : Mohamed AboSehly  Agenda ❖ Session 1 Network Essentials ❖ Session 2 Cyber Security Essentials ❖ Session 3 Distributed System  Computer Network Workshop References: o Essential Computer Science “ Paul D. Crutcher,Neeraj Kumar Singh,Peter Tiegs” o Cisco Student Guide ICND1 o CompTIA Network Session 1 (Network Essentials) Session Outlines Computer Networks Definition and Basic Terminologies TCP/IP Protocol Suite Network Access Layer (Physical Layer /Datalink Layer) Internet layer Transport layer Application Layer Session 1 (Computer Networks Definition) Computer Network : a collection of computers, and other devices, or peripherals connected together through connecting media to perform certain task such as : Share Resources Resources can be : File Sharing Devices Sharing Software Sharing with multi-user licenses. Voice and Video calls Shared Internet Access Session 1 (Network Elements) Network Elements Hardware Devices Computers – Printers –Phone – Routers - Switches Medium Wired -Wireless –Satellites Software Messages Information that travels over the medium such as Mails-WhatsApp….etc Protocols Governs how messages flow across network such as http –https-FTP-RDP Session 1 (Network Basic Terminologies ) NIC (Network Interface Card)/network adapter or LAN adapter. a hardware that enable the device to directly access the network Internal NIC (plugs into the motherboard directly) External NIC(Wireless and USB based ) Mac address: Physical Address, Unique address over the world burned on the NIC card IP address : logical address, identify each device on an IP network layer. Protocols Communication rules that all entity must agree onhttp –https-FTP- RDP Session 1 (Network Basic Terminologies ) Hub Allow different nodes to communicate with each other at the same network(Slow the network) Repeater Regenerate the signal over the same network before the signal becomes too weak or corrupted Access point (AP) allows other Wi-Fi devices to connect to a wired network. An AP is a physical location where Wi-Fi access is available. Switch Allow different nodes to communicate with each other at the same network and time without slowing each other Router Allow different networks to communicate with each other Session 1 (LAN VS WAN) Local Area Networks (LAN) a group of computers connected in small geographical area such as school, university campus or office building (100 -1000 M) Allow users to share files and services High speed of communications Under administrative Control Wide Area Networks (WAN) A WAN is a group of computers connected in Large geographical area such as country WAN can contain multiple smaller networks, such as LANs or MANs. Very low Speed Under your ISP Administrative control example of WAN is Internet Session 1 (Internet ) The internet is defined as a global mesh of interconnected networks No one actually owns the Internet Many Orgs, ISPs, Companies, Govs own pieces of Internet Infrastructure. ISOC: Internet Society IETF: Internet Engineering Task Forum ICANN: Internet Corporation for Assigned Names and Numbers Session 1 (Peer to Peer Vs Client/Server ) Peer to Peer Networks No dedicated resources to present specific service Easy to work with All nodes are the same (equal to use the resources ) Client/Server Networks Some nodes (SERVER) are dedicated to present services to other nodes (CLIENTS) Server is more powerful Mail Server Web Server File Server Print Server Session 1 (TCP/IP Protocol Suite) Why we need Protocols ? To communicate efficiently Enable data to flow from one NIC to another Control the messages and the messages quantity in the network. OSI Reference Model OSI: Open Systems Interconnect was defined by ISO in 1983 Give developers universal concepts so they can develop protocols The OSI reference model breaks this approach into layers. Session 1 (TCP/IP Protocol Suite) TCP/IP Transmission Control Protocol/Internet Protocol. Open standard protocol Cross Platform ) default protocol for all modern operating systems( Microsoft Operating Systems LINUX Operating Systems Not tied to one vendor Direct access to the Internet) TCP/IP is the internet protocol( Now internet use TCP/IP v4 Next version TCP/IP v6 Routable Session 1 (TCP/IP Protocol Suite) TCP/IP VS. OSI Model  (TCP/IP Protocol Architecture) Some Protocols in TCP/IP Suite Session 1 (TCP/IP Protocol Architecture) Network Access Layer Physical Layer - defines the electrical, Transmission medium - movements of individual Bits from one node to next Datalink Layer - Logical interface between end system and network - Error notification. (FRAMES, MAC(Media Access Control)) - Hop to Hop addressing - Error detection Mechanism (detects damaged or lost frames) Session 1 (TCP/IP Protocol Architecture) Physical Addresses (Mac) Physical Address burned on the card Unique address over the world 48-bit (6-byte) written as 12 hexadecimal digits; every byte (2 hexadecimal digits) is separated by a colon Physical addresses can be either Unicast Multicast Broadcast To check your physical address: - Ipconfig /all GetMac  Session 1 (TCP/IP Protocol Architecture) Internet / Network protocol Layer (IP Layer) Provides connectivity and path selection between two hosts (Source to Destination) Routing of data (Provide mechanism to transmit data over independent networks that are linked together) Logical addressing IPV4 , IPV6 Session 1 (TCP/IP Protocol Architecture) Internet Protocol (IP V4) Uniquely identify each device on an IP network layer. Some times we called it the logical address Every host (computer, networking device, peripheral) must have a unique address at the same network The IP address 32 bit divided into 4 octets each octet 8 bit 1 octet = 8 bit each represents from 0 to 255 separated with dots The address space of IPv4 is 232 or 4,294,967,296  Session 1 (TCP/IP Protocol Architecture) PUBLIC IP ADDRESSES (Real IP) Private IP Addresses (Local IP) Class Private Address Range A 10.0.0.0 to 10.255.255.255 B 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255 C 255 ▪ Nat is used to Translate the private IP address to public IP addresses. Session 1 (TCP/IP Protocol Architecture) How to assign IP address to device Manually Automatic ( By DHCP ) APIPA (Random /Rang : 169.254.X.X) To find your private IP Ipconfig - Ipconfig /all - Ipconfig /release - Ipconfig /renew ICMP (Ping) To test connectivity between Hosts Ping IP Ping URL Ping IP -l -n -t Session 1 (TCP/IP Protocol Architecture) Internet Protocol (IP V6) 128-bit address, provides approximately (340,282,366,920,938,463,463,374,607,431,768, 211,456) = 340 billion billion billion billion, addresses) Represented as eight groups, separated by colons, of four hexadecimal digits. The full representation may be simplified by several methods of notation; 2001:0db8:0000:0000:0000:8a2e:0370:7334 = 2001:db8::8a2e:370:7334 Session 1 (TCP/IP Protocol Architecture) Internet Of Things (IOT) Aims connect all devices to the existing Internet infrastructure. "things" that sense and collect data and send it to the internet. (Eg:- coffee maker, A.C, Washing Machine, Ceiling Fan, lights , any thing ) having sensors can be connected with internet. PRACTICAL APPLICATIONS:- Smart Homes -Smart Cities-Energy - Environment monitoring- healthcare- Management  Session 1 (TCP/IP Protocol Architecture) Transport Layer TCP UDP Transmission Control Protocol) User Datagram Protocol Reliable (Acknowledgement) Unreliable (Best –Effort delivery) Connection oriented (synchronization) Connectionless (no notification) Full duplex Full duplex Error control(Error checking(checksum ) Perform very limited error checking Data-recovery features Has no Data-recovery features E-mail Voice Streaming File sharing Video Streaming Downloading Session 1 (TCP/IP Protocol Architecture) Transport Layer addressing (Port Numbers.) ( ICANN) controls the port numbers. Well Known ports permanent used numbers. Range from 0 to 1,023 are assigned and controlled by ICANN Registered ports Range from 1,024 to 49,151 not assigned or controlled by ICANN but can be registered at ICANN to avoid duplication Dynamic ports Range from 49,152 to 65,535 are neither controlled nor registered Session 1 (TCP/IP Protocol Architecture) Application Layer Communication between processes or applications Internet Services (Client/Web Server) The World Wide Web: HTTP Naming Service: DNS File Transfer: FTP Telnet Service Electronic Mail service: IMAP, POP3, SMTP Session 1 (TCP/IP Protocol Architecture) URL is Universal Resource Locator Protocol : HTTP, HTTPS or FTP Host : is the domain name of the computer on which the information is located. Port: The URL can optionally contain the port number of the server Path: is the pathname of the file where the information is located. HTTP (Hyper Text Transfer Protocol) Supports the delivery of web pages to the client Session 1 (TCP/IP Protocol Architecture) DNS (Domain Name Servers) A way to translate human-readable names into IP addresses How the client get the website 1- check the cash 2- check the hosts file 3- Ask DNS server List of Top Level Domains (TLDs) Session 1 (TCP/IP Protocol Architecture) FTP (File Transfer Protocol) a transmission protocol that provides reliable data transfer between hosts FTP Client Use Internet Browser as FTP client. Using MS Windows built-in FTP client Third party programs “cute FTP” Session 1 (TCP/IP Protocol Architecture) Telnet /SSH or RDP Telnet/SSH is a user command and an underlying TCP/IP protocol for accessing remote computers. Telnet/SSH, an administrator can access someone else's computer remotely Remote Desktop Protocol (RDP) is a Microsoft proprietary protocol that enables remote connections to other computers, Session 1 (TCP/IP Protocol Architecture) Mail Server and Clients Mail Clients Web based : Hotmail ,gmail Non web based : Microsoft Outlook Mail Protocols SMTP (send mail transfer Protocol) send messages back and forth to other Mail Servers or Email Clients POP3 “Post Office Protocol version 3” the Email Client contacts the Mail Server to collect email messages Download messages on the hard disk can work Offline Keep the user’s quota on the server IMAP4 “Internet Message Access Protocol version 4” Retrieve only message header  Session 1 Practices Find your mac address Ipconfig /all Get mac Find your real IP addresses https://www.whatismyip.com/ Find your private IP addresses Ipconfig Ipconfig /all Ipconfig /release Ipconfig /renew ARP -a Find current session and ports on your device Netstat -n Netstat -a Find The IP of the domain Yahoo.com Nslookup Yahoo.com Session 2 (Cyber Security Essentials) Session Outlines Information Security Goals Confidentiality Integrity Availability Risks & Threats Threats & Vulnerabilities Attackers methodology & Methods Malware Types Security Defenses Firewalls (Static & Dynamic firewalls) IDS /IPS VPN Proxy Next generation Firewalls Encryption Symmetric & Asymmetric Key Cryptography  Session 2 (Security Goals) Cyber Security protect systems, networks, programs, devices and data from cyber attacks Security is a shared responsibility that each person must accept when they connect to the network. Security Goals Technically Defined Confidentiality Ensuring that information is not revealed to unauthorized persons Integrity Ensuring consistency of data and it should be possible to detect any modification of data Availability Ensuring that legitimate users are not denied access to information and resources  Session 2 (Risks & Threats ) Focus of Security is Risk Risk = Threat x Vulnerabilities Vulnerability is the degree of weakness which is found in every network and device. Threats is A person, thing, event or idea which poses danger to an asset in terms of that asset’s confidentiality, integrity, availability or legitimate use It's impossible to totally eliminate risk & There is NO simple solution to securing information Security 99.9 % Not found Why ? This can be seen through the different types of attacks that users face today. New technologies / applications New Vulnerabilities the difficulties in defending against these attacks  Session 2 (Attackers Methods) Attack: Any attempt to destroy, expose, alter, disable, steal or breaking into the information or breaking the systems or gain unauthorized access to or make unauthorized use of an asset Passive Attack Difficult to detect, because the attacker isn’t actively sending traffic (malicious or otherwise) Example: An attacker capturing packets from the network and attempting to decrypt them Active Attack Easier to detect, because the attacker is actively sending traffic that can be detected. An attacker might launch an active attack in an attempt to access information or to modify data on a system.  Session 2 (Attackers Methods) Social engineering is a term that refers to the ability of something or someone to influence the behavior of a group of people. PHISHING ATTACK: A fake web page which looks exactly like a popular website such ( facebook, twitter, Gmail , paypal , bank page ) to persuade you to enter information identity such as username , passwords and credit cards details the hacker records the username and password and then tries that information on the real site.  Session 2 (Attackers Methods) HIJACK ATTACK a hacker takes over a session between you and another individual and disconnects the other individual from the communication. You still believe that you are talking to the original party and may send private information to the hacker by accident. Insider Attack involves someone from the inside, such as a disgruntled employee, attacking the network. Session 2 (Attackers Methods) PASSWORD ATTACK An attacker tries to crack the passwords stored in a network account database or a password-protected file. Dictionary attack Brute-force attack Hybrid attack.  Session 2 (Malicious Software (Malware )types)) Backdoor or Trapdoor Secret entry point into a program ,Have been commonly used by developers Can’t be removed or scanned and the only way is to uninstall sw or format the system Viruses A virus is malicious software that is attached to another program to execute a particular unwanted function on a user's workstation. Both propagates itself & carries a payload Carries code to make copies of itself Trojan Horse program with hidden side-effects which is usually superficially attractive eg game, software upgrade etc. allows attacker to indirectly gain access they do not have directly used to propagate a virus/worm or install a backdoor Open some ports or pass some malicious files  Session 2 (Malicious Software Worms (Malware )types) Replicating but not infecting program Typically spreads over a network Using users distributed privileges or by exploiting system vulnerabilities Widely used by hackers to create zombie pc's, subsequently used for further attacks, especially dos Major issue is lack of security of permanently connected systems Zombie Program which secretly takes over another networked computer then uses it to indirectly launch attacks Often used to launch distributed denial of service (DDoS) attacks Ransomware Malware that locks a computer or device or encrypts data (Crypto ransomware) on an infected endpoint with an encryption key ,only the attacker knows the key the data unusable until the victim pays a ransom (usually cryptocurrency, such as Bitcoin).  Session 2 (Malicious Software (Malware )types) DoS Attack Denial of service is about without permission knocking off services, used for crashing the whole system. This kind of attacks are easy to launch and it is hard to protect a system against them. Consume host resources Memory Processor cycles Consume network resources Bandwidth Dos Attack (Ping of Death) DDoS Attack A distributed denial of service attack uses multiple machines to prevent the legitimate use of a service. TCP SYN flood  Session 2 (Malicious Software (Malware )types) Spam Spam is a serious network threat that can overload ISPs, email servers and individual end-user systems. A person or organization responsible for sending spam is called a spammer. Spammers often make use of unsecured email servers to forward email. Spammers can use hacking techniques, such as viruses, worms and Trojan horses to take control of home computers. Spyware Spyware is any program that gathers personal information from your computer without your permission or knowledge. This information is sent to advertisers or others on the Internet and can include passwords and account numbers. Tracking Cookies Cookies are a form of spyware but are not always bad. They are used to record information about an Internet user when they visit websites Session 2 (Attacks Mitigation) Firewall A Firewall is one of the most effective security tools available for protecting internal network users from external threats. A firewall resides between two or more networks and controls the traffic between them as well as helps prevent unauthorized access Static Packet Filtering (stateless firewall ) - Prevents or allows access based on IP or MAC addresses. Dynamic Packet Filtering (state full firewall) Incoming packets must be legitimate responses to requests from internal hosts. Unsolicited packets are blocked unless permitted specifically. SPI can also include the capability to recognize and filter out specific types of attacks such as DoS. Session 2 (Attack Mitigation) Proxy Server A computer system (or an application program) that intercepts internal user requests and then processes that request on behalf of the user Goal is to hide the IP address of client systems inside the secure network VPN It Tunnel the traffic between the Two Sides of Network Kinds: Remote Access VPN Site to Site VPN  Session 2 (Attack Mitigation ) Intrusion Detection and Prevention Systems NIDS: Watch the Network Traffic and if there is Intrusion it Detects that there is Bad traffic Flow. it send alarms and logs NIPS: Stops the traffic if it detects that there is intrusion Signature-based: look for the perfect match Next generation Firewall (NGFW) is,a “deep-packet inspection firewall that moves beyond port/protocol inspection and blocking to add application-level inspection, intrusion prevention, and bringing intelligence from outside the firewall.”  Session 2 (Encryption) Encryption encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Unencrypted data, called plaintext, is sent through an encryption algorithm to generate a ciphertext. A key is used for encryption. in a symmetric encryption algorithm, the same key is also used for decryption. (Not secure) needs to be a secure way for the two sides to have the same key  Session2 Practices How to use your local firewall to block a port and stop DOS attack from a zombie device Session 3 (Distributed Systems) Session Outlines Distributed Systems overview Definition and Basic Terminologies Why build a distributed system? Types of Distributed Systems The 4 Distributed Systems architecture Distributed System Examples Cloud computing Cloud computing service models Cloud computing deployment models  Session 3 (Distributed System) Distributed Systems Is a group of computers working together as to appear as a single computer to the end-user.  Session 3 (Distributed System) Centralized system VS Distributed system Centralized system: State stored on a single computer ○ Simpler ○ Easier to understand ○ Can be faster for a single user Distributed system: State divided over multiple computers ○ More robust(can tolerate failures) ○ More scalable (often supports many users) ○ More complex  Session 3 (Distributed System) Why build a distributed system? One interface to the end-user. Performance maximize resources and information while preventing failures Reliability if one system fails, it won't affect the availability of the service Dependency on cloud Scaling Distributed system is growing…They are everywhere Networks , Could Computing, Distributed Database Systems  Session 3 (Distributed System) Distributed systems must have : Network that connects all components (Hardware, or Software) Messages passed between machines contain forms of data that the systems want to share like databases, objects, and files. The way the messages are communicated reliably whether it’s sent, received, acknowledged or how a node retries on failure is an important feature of a distributed system. Distributed systems were created out of necessity as services and applications needed to scale and new machines needed to be added and managed.  Session 3 (Types of Distributed System) Four architecture types : 1. Client-server: a server as a shared resource like (a printer, database, or a web server) Multiple clients use the shared resource. 2. Three-tier: - clients no longer need to be intelligent - can rely on a middle tier to do the processing and decision making. - Most of the first web applications fall under this category. -The middle tier could be called an agent that receives requests from clients, and then forwards it on to the servers.  Session 3 (Types of Distributed System) 3- Multi-tier (n-tier) Enterprise web services first created n-tier or multi-tier systems architectures. -This popularized the application servers that contain the business logic - n-tier interacts both with the data tiers and presentation tiers. - Ex : google.com 4- Peer-to-peer : No centralized or special machine that does the heavy lifting and intelligent work in this architecture. All the decision making and responsibilities are split up amongst the machines involved and each could take on client or server roles. Blockchain is a good example of this. Session 3 (Distributed System Examples) Domain Name System (DNS) Distributed lookup table of hostname to IP address Facebook & Google use distributed systems extensively Massive scale Fast enough Very reliable Email servers (SMTP) Cloud Computing Virtualization  Session 3 (Virtualization) Virtualization Is a technology that run multiple same or different operating systems which is completely isolated from each other Example: run both windows and Linux on the same machine Virtualization is different from Dual Boot ? Dual Boot run only one OS at the same time Virtualization run multiple OS at the same time Virtualization Benefits Consolidation Redundancy Legacy hardware Migration Centralized management  Session 3 (Cloud computing ) Cloud computing A pool of resources that can be rapidly provisioned in an automated, on-demand manner. Value of cloud computing is : Economies of scale Elastic enough to scale with the needs of your organization. Cost and operational benefits Easily accessed by users no matter where they reside Session 3 (Cloud computing service models) Cloud computing service models  Session 3 (Cloud computing service models) Software as a service (SaaS). Customers are provided access to an application running on a cloud infrastructure. but the customer has no knowledge of, and does not manage or control, the underlying cloud infrastructure. Platform as a service (PaaS). Customers can deploy supported applications onto the provider’s cloud infrastructure, but the customer has no knowledge of, and does not manage or control, the underlying cloud infrastructure. The company owns the deployed applications and data, and it is therefore responsible for the security of those applications and data. Infrastructure as a service (IaaS). Customers can provision processing, storage, networks, and other computing resources, and deploy and run operating systems and applications. the customer has no knowledge of, and does not manage or control, the underlying cloud infrastructure. The customer has control over operating systems, storage, and deployed applications, along with some networking components (for example, host firewalls). The company owns the deployed applications and data, and it is therefore responsible for the security of those applications and data.  Session 3 (Cloud computing deployment model) Public. A cloud infrastructure that is open to use by the general public. It’s owned, managed, and operated by a third party (or parties), and it exists on the cloud provider’s premises. Community. A cloud infrastructure that is used exclusively by a specific group of organizations. Private. A cloud infrastructure that is used exclusively by a single organization. It may be owned, managed, and operated by the organization or a third party (or a combination of both), and it may exist on premises or off premises. Hybrid. A cloud infrastructure that comprises two or more of the aforementioned deployment models, bound by standardized or proprietary technology that enables data and application portability (for example, fail over to a secondary data center for disaster recovery or content delivery networks across multiple clouds).  Session 3 Practices Use the Vmware Workstation tool to host the two different OS on your machine Thank You