The document provides a brief history of the Internet and an overview of the Domain Name System (DNS). It discusses the development of early packet networks like ARPANET and the invention of TCP/IP. It also describes the roles of organizations like ICANN and ARIN in managing domain names, IP addresses, and other Internet resources. Finally, it explains the basic functioning of DNS through record types like A, MX, NS, and PTR that map domain names to IP addresses and vice versa.
DNS is a network service that enables clients to resolve names to IP address and vice-versa.
Allows machines to be logically grouped by domain names.
Provides email routing information.
Build Dynamic DNS server from scratch in C (Part1)Yen-Kuan Wu
This is my final project. The purpose is that I don't get any course about Network, so I try to implement DNS server and learn from practicing.
In this slide, it would cover brief introduction of ddns server, prerequisite for building protocol, aims of my project and all of pitfalls I have met.
Demo resolver.
I would finish this project and provide the part2 of slide.
This document provides an overview of DNSSEC including:
- DNSSEC adds new resource record types and cryptographic signatures to securely publish DNS records. This establishes a "chain of trust" from the root zone to authoritative name servers.
- Key components of DNSSEC include new resource records, cryptographic signatures to validate records haven't been tampered with, and header flags to indicate validation status.
- Maintaining DNSSEC requires periodic key rollovers and other administrative tasks to ensure the ongoing integrity of the domain name system.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
This document provides an overview of the Domain Name System (DNS) and why it needs to be secured. It discusses the history and evolution of DNS from its origins in host files to its current hierarchical structure. The document also describes how DNS Secure Extensions (DNSSEC) works to secure DNS through digital signatures and a chain of trust from the root zone down. It explains common DNS security threats like cache poisoning and how DNSSEC aims to prevent them.
This document provides information on configuring the Berkeley Internet Name Domain (BIND) DNS server. It describes DNS and how resource records are organized hierarchically with domains and subdomains separated by periods. The document outlines the files needed to configure BIND, including the name.conf, zone files, and loopback file. It explains the directory structure for non-chrooted and chrooted configurations and provides troubleshooting commands.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
The document is a slide presentation that provides an introduction to the Domain Name System (DNS). It discusses key concepts such as:
- DNS provides a mapping between domain names that are easy for humans to remember (e.g. www.example.com) and IP addresses that computers use to locate services.
- The DNS database is distributed across multiple name servers around the world to provide reliability and scalability. Changes propagate according to timing parameters.
- Name servers include authoritative servers that store official data for a zone, and recursive servers that handle lookups on behalf of clients and cache results.
- The domain name space is hierarchical with delegation of subdomains, and zones define administrative boundaries for domain data.
DNS is a network service that enables clients to resolve names to IP address and vice-versa.
Allows machines to be logically grouped by domain names.
Provides email routing information.
Build Dynamic DNS server from scratch in C (Part1)Yen-Kuan Wu
This is my final project. The purpose is that I don't get any course about Network, so I try to implement DNS server and learn from practicing.
In this slide, it would cover brief introduction of ddns server, prerequisite for building protocol, aims of my project and all of pitfalls I have met.
Demo resolver.
I would finish this project and provide the part2 of slide.
This document provides an overview of DNSSEC including:
- DNSSEC adds new resource record types and cryptographic signatures to securely publish DNS records. This establishes a "chain of trust" from the root zone to authoritative name servers.
- Key components of DNSSEC include new resource records, cryptographic signatures to validate records haven't been tampered with, and header flags to indicate validation status.
- Maintaining DNSSEC requires periodic key rollovers and other administrative tasks to ensure the ongoing integrity of the domain name system.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
This document provides an overview of the Domain Name System (DNS) and why it needs to be secured. It discusses the history and evolution of DNS from its origins in host files to its current hierarchical structure. The document also describes how DNS Secure Extensions (DNSSEC) works to secure DNS through digital signatures and a chain of trust from the root zone down. It explains common DNS security threats like cache poisoning and how DNSSEC aims to prevent them.
This document provides information on configuring the Berkeley Internet Name Domain (BIND) DNS server. It describes DNS and how resource records are organized hierarchically with domains and subdomains separated by periods. The document outlines the files needed to configure BIND, including the name.conf, zone files, and loopback file. It explains the directory structure for non-chrooted and chrooted configurations and provides troubleshooting commands.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
The document is a slide presentation that provides an introduction to the Domain Name System (DNS). It discusses key concepts such as:
- DNS provides a mapping between domain names that are easy for humans to remember (e.g. www.example.com) and IP addresses that computers use to locate services.
- The DNS database is distributed across multiple name servers around the world to provide reliability and scalability. Changes propagate according to timing parameters.
- Name servers include authoritative servers that store official data for a zone, and recursive servers that handle lookups on behalf of clients and cache results.
- The domain name space is hierarchical with delegation of subdomains, and zones define administrative boundaries for domain data.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
DNS (Domain Name System) is a hierarchical naming system that translates domain names to IP addresses and vice versa. A DNS server is a computer that runs DNS services to provide name resolution. DNS works by querying multiple levels of DNS servers, starting from the root servers, then TLD (top-level domain) servers, then authoritative name servers, to ultimately resolve domain names to IP addresses.
DNS, which stands for domain name system, controls your domain name's website and email settings. When visitors go to your domain name, its DNS settings control which company's server it reaches out to.
Nslookup and dig are command line tools used to query DNS servers and look up DNS records like A, MX, and NS records. Nslookup has both an interactive and command line mode, while dig is easier to use but performs the same functions. These tools are useful for troubleshooting DNS and connectivity issues by comparing results across different DNS servers and ensuring zone data propagation. DNSStuff.com is recommended as a better way to view and manage DNS records than using command line tools.
This document provides an introduction to DNS (Domain Name System) in 3 paragraphs:
It explains that DNS was created to address the problems with using a centralized HOSTS.TXT file to map hostnames to IP addresses as the Internet grew. DNS introduced a distributed and hierarchical namespace that maps domain names to IP addresses through a global network of name servers.
It describes the basic structure and functionality of DNS, including that it is organized in a tree structure with top-level domains at the root, each domain can be delegated to different administrators, and name servers contain parts of the distributed database that maps domain names and resource records like A records (IPv4 addresses) and MX records (mail servers).
The
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
Domain Name System (DNS) - Domain Registration and Website Hosting BasicsAsif Shahzad
I teach Web Technologies course at COMSATS University to undergrad students. These are lectures slides prepared for students. I thought to share it with all. Hope you would like it. It contains good enough details about how DNS, Hosting and Domain Registration works.
Apache Drill 1.0 has been released after nearly three years of development involving 45 code contributors and countless other contributors. Drill provides a SQL interface for analyzing both structured and unstructured data across numerous data sources. It aims to execute queries fast by leveraging columnar encodings and scaling out queries rather than scaling up. Drill also aims to support iterative exploration and querying of data without requiring data preparation. Future plans for Drill include continued monthly releases, integration with other technologies like JDBC and Cassandra, and tools to deploy Drill on EMR and EC2.
This document discusses DNS configuration. It provides an overview of DNS and its history. It describes DNS name space and how it works with an inverted tree structure. It discusses DNS name servers and zones, including forward and reverse lookup zones. It outlines the steps to configure DNS on a server, which includes installing bind9, editing configuration files for zones, and restarting the bind9 service. Tests are done using nslookup to resolve names and addresses.
The document provides an overview of DNS (Domain Name System) including registration records, common record types like A, MX, CNAME, NS, SOA, PTR and TXT records. It describes DNS queries, responses, zone transfers, and structure and interpretation of DNS records. Key points covered include registration information from WHOIS, mapping of domain names to IP addresses using record types, DNS server hierarchy, and use of records for mail servers and reverse lookups.
The document discusses DNS attacks and how to prevent them. It begins by explaining what DNS is and how it works to translate domain names to IP addresses. It then outlines several common attacks against DNS like cache poisoning, amplification attacks, and DDoS attacks. The document recommends approaches to secure DNS like DNSSEC, which adds digital signatures to authenticate DNS data and prevent spoofing. It provides details on how DNSSEC works through cryptographic signing of DNS records and validation of signatures up the DNS hierarchy.
This document provides a reference for various Unix/Linux commands and their uses. It lists commands for directory navigation and file manipulation, process management, file permissions, networking, compression, system information, searching, and more. Descriptions are provided for common commands like ls, cd, pwd, mkdir, cat, more, head, tail, touch, rm, cp, mv, ln, ps, top, kill, ping, whois, dig, tar, gzip, date, cal, uptime, grep, locate, and find.
About DNS name service.
If you looking for Domain Name Registar, check out the review: https://medium.com/@JohnBeardslee/best-domain-name-registrars-top-recommendations-b3d65128b46a
When you are new to Linux in 2020, go for the latest Mint or Fedora. If you only want to practice the Linux command line then install one Debian server and/or one CentOS server
(without graphical interface).
This document summarizes full text search capabilities in PostgreSQL. It begins with an introduction and overview of common full text search solutions. It then discusses reasons to use full text search in PostgreSQL, including consistency and no need for additional software. The document covers basics of full text search in PostgreSQL like to_tsvector, to_tsquery, and indexes. It also covers fuzzy full text search using pg_trgm and functions like similarity. Other topics mentioned include ts_headline, ts_rank, and the RUM extension.
A presentation on DNS concepts. It covers the topics DNS Introduction, DNS Hierarchy, DNS Resolution Process,
DNS Components, DNS Types, DNSSEC, DNS over TLS (DoT) & HTTPS (DoH), Oblivious DNS (ODoH).
Quite often "new" people are only "new" to Postgres. This is my summary of do's and don'ts when it comes to teaching Postgres, what to take note on, with emphasis on teaching
This document discusses Linux resource management techniques such as ulimits, quotas, CPU affinity, control groups (cgroups), and more. It provides examples of configuring ulimits, setting CPU affinity for processes and hardware interrupts, and hierarchical control of resources using cgroups subsystems like CPUSET, CPU, CPUACCT, MEMORY, BLKIO, and DEVICES. The presenter is a Linux system administrator sharing their expertise in optimizing system resource usage.
This document discusses DHCP (Dynamic Host Configuration Protocol). It provides an overview of DHCP including how it works, the basics of DHCP, and how DHCP is used to assign IP addresses and other network configuration parameters to clients. It also presents a case study of setting up a DHCP server to support a network with both static and dynamic IP address assignments. The key components and functions of a DHCP server are explained as well as the steps a client takes to obtain an IP address using DHCP.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
DNS (Domain Name System) is a hierarchical naming system that translates domain names to IP addresses and vice versa. A DNS server is a computer that runs DNS services to provide name resolution. DNS works by querying multiple levels of DNS servers, starting from the root servers, then TLD (top-level domain) servers, then authoritative name servers, to ultimately resolve domain names to IP addresses.
DNS, which stands for domain name system, controls your domain name's website and email settings. When visitors go to your domain name, its DNS settings control which company's server it reaches out to.
Nslookup and dig are command line tools used to query DNS servers and look up DNS records like A, MX, and NS records. Nslookup has both an interactive and command line mode, while dig is easier to use but performs the same functions. These tools are useful for troubleshooting DNS and connectivity issues by comparing results across different DNS servers and ensuring zone data propagation. DNSStuff.com is recommended as a better way to view and manage DNS records than using command line tools.
This document provides an introduction to DNS (Domain Name System) in 3 paragraphs:
It explains that DNS was created to address the problems with using a centralized HOSTS.TXT file to map hostnames to IP addresses as the Internet grew. DNS introduced a distributed and hierarchical namespace that maps domain names to IP addresses through a global network of name servers.
It describes the basic structure and functionality of DNS, including that it is organized in a tree structure with top-level domains at the root, each domain can be delegated to different administrators, and name servers contain parts of the distributed database that maps domain names and resource records like A records (IPv4 addresses) and MX records (mail servers).
The
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
The Domain Name System (DNS) is a critical part of Internet infrastructure and the largest distributed Internet directory service. DNS translates names to IP addresses, a required process for web navigation, email delivery, and other Internet functions. However, the DNS infrastructure is not secure enough unless the security mechanisms such as Transaction Signatures (TSIG) and DNS Security Extensions (DNSSEC) are implemented. To guarantee the availability and the secure Internet services, it is important for networking professionals to understand DNS concepts, DNS Security, configurations, and operations.
This course will discuss the concept of DNS Operations in detail, mechanisms to authenticate the communication between DNS Servers, mechanisms to establish authenticity, and integrity of DNS data and mechanisms to delegate trust to public keys of third parties. Participant will be involved in Lab exercises and do configurations based on number of scenarios.
Domain Name System (DNS) - Domain Registration and Website Hosting BasicsAsif Shahzad
I teach Web Technologies course at COMSATS University to undergrad students. These are lectures slides prepared for students. I thought to share it with all. Hope you would like it. It contains good enough details about how DNS, Hosting and Domain Registration works.
Apache Drill 1.0 has been released after nearly three years of development involving 45 code contributors and countless other contributors. Drill provides a SQL interface for analyzing both structured and unstructured data across numerous data sources. It aims to execute queries fast by leveraging columnar encodings and scaling out queries rather than scaling up. Drill also aims to support iterative exploration and querying of data without requiring data preparation. Future plans for Drill include continued monthly releases, integration with other technologies like JDBC and Cassandra, and tools to deploy Drill on EMR and EC2.
This document discusses DNS configuration. It provides an overview of DNS and its history. It describes DNS name space and how it works with an inverted tree structure. It discusses DNS name servers and zones, including forward and reverse lookup zones. It outlines the steps to configure DNS on a server, which includes installing bind9, editing configuration files for zones, and restarting the bind9 service. Tests are done using nslookup to resolve names and addresses.
The document provides an overview of DNS (Domain Name System) including registration records, common record types like A, MX, CNAME, NS, SOA, PTR and TXT records. It describes DNS queries, responses, zone transfers, and structure and interpretation of DNS records. Key points covered include registration information from WHOIS, mapping of domain names to IP addresses using record types, DNS server hierarchy, and use of records for mail servers and reverse lookups.
The document discusses DNS attacks and how to prevent them. It begins by explaining what DNS is and how it works to translate domain names to IP addresses. It then outlines several common attacks against DNS like cache poisoning, amplification attacks, and DDoS attacks. The document recommends approaches to secure DNS like DNSSEC, which adds digital signatures to authenticate DNS data and prevent spoofing. It provides details on how DNSSEC works through cryptographic signing of DNS records and validation of signatures up the DNS hierarchy.
This document provides a reference for various Unix/Linux commands and their uses. It lists commands for directory navigation and file manipulation, process management, file permissions, networking, compression, system information, searching, and more. Descriptions are provided for common commands like ls, cd, pwd, mkdir, cat, more, head, tail, touch, rm, cp, mv, ln, ps, top, kill, ping, whois, dig, tar, gzip, date, cal, uptime, grep, locate, and find.
About DNS name service.
If you looking for Domain Name Registar, check out the review: https://medium.com/@JohnBeardslee/best-domain-name-registrars-top-recommendations-b3d65128b46a
When you are new to Linux in 2020, go for the latest Mint or Fedora. If you only want to practice the Linux command line then install one Debian server and/or one CentOS server
(without graphical interface).
This document summarizes full text search capabilities in PostgreSQL. It begins with an introduction and overview of common full text search solutions. It then discusses reasons to use full text search in PostgreSQL, including consistency and no need for additional software. The document covers basics of full text search in PostgreSQL like to_tsvector, to_tsquery, and indexes. It also covers fuzzy full text search using pg_trgm and functions like similarity. Other topics mentioned include ts_headline, ts_rank, and the RUM extension.
A presentation on DNS concepts. It covers the topics DNS Introduction, DNS Hierarchy, DNS Resolution Process,
DNS Components, DNS Types, DNSSEC, DNS over TLS (DoT) & HTTPS (DoH), Oblivious DNS (ODoH).
Quite often "new" people are only "new" to Postgres. This is my summary of do's and don'ts when it comes to teaching Postgres, what to take note on, with emphasis on teaching
This document discusses Linux resource management techniques such as ulimits, quotas, CPU affinity, control groups (cgroups), and more. It provides examples of configuring ulimits, setting CPU affinity for processes and hardware interrupts, and hierarchical control of resources using cgroups subsystems like CPUSET, CPU, CPUACCT, MEMORY, BLKIO, and DEVICES. The presenter is a Linux system administrator sharing their expertise in optimizing system resource usage.
This document discusses DHCP (Dynamic Host Configuration Protocol). It provides an overview of DHCP including how it works, the basics of DHCP, and how DHCP is used to assign IP addresses and other network configuration parameters to clients. It also presents a case study of setting up a DHCP server to support a network with both static and dynamic IP address assignments. The key components and functions of a DHCP server are explained as well as the steps a client takes to obtain an IP address using DHCP.
DNS is a hierarchical system that matches domain names to IP addresses. It allows humans to use easy-to-remember domain names instead of hard-to-remember IP addresses. DNS works by routing requests through a hierarchy of root, top-level, and authoritative name servers to resolve domain names to IP addresses. The domain namespace is structured in a tree hierarchy from top-level domains down to individual websites. DNS uses primary and secondary name servers to host authoritative records for domains and subdomains.
DNS (Domain Name System) is an application layer protocol that translates host names to IP addresses. DNS was created to make addressing easier for users to remember and access resources, as the internet grew larger and IP addresses became more difficult to memorize. Before DNS existed, host files or centralized servers were used to map names to addresses but became infeasible as the number of users and hosts increased substantially. DNS works by having name servers that cache address mappings and can be queried by clients to lookup names. However, DNS is susceptible to various security issues like cache poisoning, denial of service attacks, and reflection/amplification attacks which aim to corrupt mappings, overload servers, or spoof source addresses. Techniques to improve security include using
The document discusses domain name servers (DNS), explaining that DNS translates domain names to IP addresses, allowing computers to connect to websites by name instead of numeric address. It describes how DNS works by checking its own database and cache for domain name to IP address mappings, then querying other DNS servers if needed to find the correct mapping to return. The document also mentions configuring a DNS server.
The document discusses the Domain Name System (DNS) which maps domain names to IP addresses. DNS uses a client-server model where clients (resolvers) query name servers to lookup addresses. It describes the hierarchical namespace structure and how names are organized into domains with labels separated by dots. Resource records containing domain, type, class and data are stored in distributed databases to map names and addresses. Caching improves performance by storing recent lookups.
DHCP is a protocol that automatically assigns IP addresses and other network configuration parameters to clients. It allows administrators to change network settings centrally on the DHCP server rather than having to configure each client individually. The DHCP server uses the dhcpd.conf configuration file and dhcpd.leases database to manage IP addresses and other settings for clients on the network. The DHCP relay agent can forward requests from clients without a local DHCP server to servers on other subnets.
The document discusses various applications in the application layer of the Internet protocol stack, including the Domain Name System (DNS), electronic mail, the World Wide Web, streaming audio and video, and content delivery. It provides details on DNS, describing how domain names are organized hierarchically and mapped to IP addresses, and how name servers function to look up domain names. It also gives overviews of electronic mail/email, noting its widespread use both personally and for business, and the problem of spam.
The document provides an overview of the Dynamic Host Configuration Protocol (DHCP) including its history, operation, message types, client states, security considerations, and future developments. It also outlines testing procedures for DHCP clients and servers to validate their basic functionality and behaviors.
This document discusses IP addresses, DNS, DHCP, and related networking concepts. It defines an IP address as a unique number assigned to devices on a network that allows them to be identified and located. It describes IPv4 and IPv6 address standards and how network and host IDs are defined for different address classes. It also explains loopback addresses, APIPA addresses, DNS and how it translates names to addresses, and DHCP and how it dynamically assigns IP addresses and configuration information to devices on a network.
DHCP evolved from RARP and BOOTP protocols to dynamically assign IP addresses to clients on a network. The DHCP server maintains a pool of IP addresses and configuration information. When a client requests an IP, the DHCP server allocates one from the pool along with other configuration and leases it to the client for a set time. This allows for IP addresses to be reused more efficiently as clients connect and disconnect from the network.
The document discusses the Domain Name System (DNS) which maps domain names to IP addresses. It describes how DNS works hierarchically with a root server at the top level, below which are generic, country-specific and other domain levels. DNS servers store and distribute this mapping information across multiple computers to avoid a single point of failure. Primary DNS servers store and update zone files mapping domain names to IP addresses, while secondary servers transfer this information from primary servers.
DHCP is a protocol that dynamically assigns IP addresses and other network configuration parameters to devices on a network. It uses a client-server model where DHCP clients make requests to DHCP servers which maintain pools of addresses. A DHCP client will broadcast requests at initialization and use a 4-step process to get an address assigned. It will later enter renewal states to extend its lease before initialization again if needed. This allows for efficient dynamic allocation and management of IP addresses on a network.
The document discusses the Domain Name System (DNS) and its components. It explains what DNS is, how it works to translate domain names to IP addresses, the different record types used in DNS like A, NS, MX records. It describes DNS name servers, resolvers, zones and namespaces. It provides examples of DNS configuration files for both master and slave name servers as well as sample zone files mapping names to IP addresses.
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
Install and Understand DNSSEC in Linux Server running BIND 9 with CHROOT JAIL system and Service.
By Utah Networxs
Follow - @fabioandpires
Follow - @utah_networxs
This document provides an overview and introduction to DNS and DNSSEC. It begins with introducing the presenter, Nurul Islam Roman, and his background and areas of expertise. The overview section lists the topics to be covered, including DNS overview, forward and reverse DNS, DNS security overview, TSIG, and DNSSEC. The document then delves into explanations of DNS overview, how it works, its features and components. It also covers IP addresses vs domain names, the DNS tree hierarchy, domains, root servers, resolvers, authoritative and recursive nameservers. Finally, it discusses resource records, common RR types, reverse DNS, delegation, glue records and responsibilities around APNIC and ISPs for reverse delegations.
The document introduces the DNS system by explaining its purpose of mapping names to resources for easier lookup than numbers. It describes DNS features like global distribution, loose coherency, scalability, reliability, and dynamic updates. Key concepts are explained such as hierarchical DNS names, domains and delegation of subdomains, authoritative and recursive name servers, resource records including SOA and NS records, and how TTL and zone refresh timers maintain consistency.
1) The document discusses DNS basics including its hierarchical database structure with root and top level domains (TLDs) at the top, and its main components like authoritative servers, recursive resolvers, and resource records.
2) It explains key DNS concepts like domains, zones, and delegation between zones. Common resource record types and a sample zone file are also described.
3) The document covers potential DNS issues like cache poisoning and vulnerabilities if data is not validated, which DNS Security Extensions (DNSSEC) aims to address through cryptographic signing of resource records.
Demystifying MS17-010: Reverse Engineering the ETERNAL ExploitsPriyanka Aash
"MS17-010 is the most important patch in the history of operating systems, fixing remote code execution vulnerabilities in the world of modern Windows. The ETERNAL exploits, written by the Equation Group and dumped by the Shadow Brokers, have been used in the most damaging cyber attacks in computing history: WannaCry, NotPetya, Olympic Destroyer, and many others.
Yet, how these complicated exploits work has not been made clear to most. This is due to the ETERNAL exploits taking advantage of undocumented features of the Windows kernel and the esoteric SMBv1 protocol.
This talk will condense years of research into Windows internals and the SMBv1 protocol driver. Descriptions of full reverse engineering of internal structures and all historical background info needed to understand how the exploit chains for ETERNALBLUE, ETERNALCHAMPION, ETERNALROMANCE, and ETERNALSYNERGY work will be provided.
This talk will also describe how the MS17-010 patch fixed the vulnerabilities, and identify additional vulnerabilities that were patched around the same time."
This document provides an overview of the Domain Name System (DNS) including key concepts like root name servers, top level domains, name server records, DNS records like A, MX, CNAME, TXT, SRV and PTR records. It discusses DNS configuration files, caching servers, DNS lookups, zone transfers between name servers and round robin DNS. Examples are given for various DNS record types. Useful DNS tools and links are also listed.
The document provides an overview of DNS history and requirements for maintaining a DNS infrastructure. It discusses how DNS has evolved since 1983 to support features like load balancing, geobalancing, failover, and security protocols. When choosing a DNS software product or service provider, key considerations include scalability, supported features, dynamic configuration, failover capabilities, and protection against DDoS attacks. Maintaining DNS with multiple service providers can improve performance and reliability compared to a single provider.
A contemporary network service heavily depends on domain name system operating normally. Yet, often issues and caveats of typical DNS setup are being overlooked. DNS (like BGP before) is expected to "just work" everywhere, however, just as BGP, this is a complex protocol and a complex solution where a lot of things could go wrong in multiple ways under different circumstances. This talk is supposed to provide some assistance both in maintaining your own DNS infrastructure and in relying on service providers doing this.
This document summarizes a presentation about DNS (Domain Name System) for developers. It discusses the basics of how DNS works to map domain names to IP addresses, different DNS record types like A, CNAME, and MX records, DNS zones, security considerations like cache poisoning and DNSSEC, using DNS for failover, load balancing, and CDNs, storing configuration data and doing service discovery in DNS, and some unconventional uses of DNS like tunneling HTTP and IP traffic over DNS. The presentation provides examples and demonstrations of these DNS concepts and techniques.
We browse the Internet. We host our applications on a server or a cloud that is hooked up with a nice domain name. That’s all there is to know about DNS, right? This talk is a refresher about how DNS works. How we can use it and how it can affect availability of our applications. How we can use it as a means of configuring our application components. How this old geezer protocol is a resilient, distributed system that is used by every Internet user in the world. How we can use it for things that it wasn’t built for. Come join me on this journey through the innards of the web!
DNS is a distributed system that maps domain names to IP addresses. It uses a hierarchy of servers, with root servers at the top level responsible for top-level domains like .com and .org. DNS servers answer queries recursively or iteratively to lookup IP addresses. The Time-To-Live (TTL) field of DNS records determines how long caches store the records before refreshing from authoritative servers.
The document discusses the history and evolution of the Domain Name System (DNS). It describes how early computer networks like ARPANET used hosts.txt files to map hostnames to IP addresses, but this approach did not scale well. DNS was developed in the 1980s to provide a distributed, hierarchical database to resolve hostname lookups. DNS uses a client-server model with nameservers to store records and respond to queries. The 13 root servers delegate authority to top-level domains which in turn delegate to authoritative nameservers for each domain.
A curious case of broken DNS responses (Coloclue Presents - Nov 2019)Babak Farrokhi
The document describes a case where certain DNS queries, such as for MX records of specific domains, were returning incorrect responses from public DNS resolvers like Google's 8.8.8.8. The author developed tools like dnsping and dnstraceroute to investigate further and discovered a rogue DNS server impersonating the public resolver. Using these tools, the author traced the traffic to a DNS server located nearby that was selectively redirecting queries. Further tests showed the redirection was likely done for privacy reasons in some cases but could also be used for malicious purposes like censorship or service hijacking. The author advocates using encrypted DNS protocols and running your own recursive resolver to avoid man-in-the-middle attacks.
Learning Erlang (from a Prolog dropout's perspective)elliando dias
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The document provides step-by-step instructions for configuring a master DNS server on Linux. It discusses installing bind packages, configuring the named.conf and zones files to define domains and records, creating zone files for forward and reverse lookups, restarting services, and testing the name resolution. Key aspects covered include defining the master server IP, domains and records in the zones file, generating zone files from templates, configuring firewall rules and resolving configuration.
The network layer routes packets between devices on a network through multiple hops. It must address scalability issues around representing addresses and routing packets as networks grow large. Routers connect multiple local area networks, which may use different link layer technologies. IP addresses use a hierarchical structure to improve routing scalability. Classless Inter-Domain Routing (CIDR) allows arbitrary allocation of addresses and subnets to minimize routing tables.
DNS is a globally distributed database that translates domain names to IP addresses. It consists of a name space organized in a hierarchical tree structure, servers that store data about parts of the name space, and resolvers that query servers to map names to addresses. The resolution process involves recursively querying servers at higher levels, like root and TLD servers, until reaching an authoritative name server that can provide the address. Caching improves performance by storing previous lookups.
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This document summarizes an IP fragmentation attack on DNS resolvers. It exploits IP fragmentation and reassembly to reduce the entropy for cache poisoning from 32 bits to 16 bits. There are two types of attacks - one triggers fragmentation through spoofed ICMP messages, while the other registers a specially crafted zone to generate oversized responses. The attacks allow modifying DNS response fragments off-path to poison caches. Defenses include DNSSEC and workaround like ignoring certain ICMP and limiting response sizes.
2. Short History of the Internet
-- Packet switching as opposed to circuit
switching. Designed to avoid any failures.
○ ARPANET -- Advanced Research Projects Agency
Network -- the 1st packet switching (or store and
foward) network (DARPA work) (split
DDD/MILNET in 80's)
i. internet precursor
a. AlohaNet -- First wireless packet network
ii. Used packet radios, and led to CSMA leading to
ethernet by Robert Metcalf (Xerox Parc-> 3com)
iii. precursor to 1G+ mobile channels... for GPRS
and SMS, AX.25 (amature X.25 -- packet
switched WAN non ISO, non TCP/IP)
●
3. Some the real inventors
(Gore) A
● Vint Cerf
○ TCP/IP (co-inventor) / program manager of DARPA
○ Moved to MCI (email), key figure in setting up
ICANN (Internet Corporation for Assigned Numbers
and Names), Internet Society, ...
● Bob Kahn
○ TCP/IP (co-inventor)
○ BBN and first IMPs (interface Message Processor) ,
(ran ARAPNET routers), ...
● Leonard Klienrock
○ UCLA prof. -- queiueng theory (packet networks)
○ Supervized first ARPANET connection at UCLA - '69
○ IMP build out and usage
●
4. Some the real inventors
(Gore)
● John Postel
○ RFC's (Request For Commments) editor
■ intially idea flesh out for ARPANET or any
DARPA research
■ now memoradim of ITEF , sometimes standard
○ coordinated IANA (Internet Assigned Numbers
Authority)
○ Setup NIC (Network Information Center) with SRI
(Standford Research Institute)
■ 1st DNS authority was the NIC
■ Requested current DNS -- wrote by Paul
Mockepetris in 1983
5. Some the real inventors
(Gore)
● Paul Vixie
○ BIND and Cron -- author of current versions
■ BIND - from UCB unix, Berkely Internet Name
Domain
○ Founder of ISC -- Internet Systems Consortium
(BIND, DHCP, internet survey report (ML), ...)
○ co-inventor maintainer of MAPS (Mail Abuse
Prevention System)
■ 1st email spam blocking lists built on DNS
○ ARIN board member
○ Security/Stability member for ICANN
7. Todays Organizations
● ICANN - Internet Corporation for Assigned
Names and Numbers
a. Coordination of internet unique identifiers
(Domains, IPs, ASNs, ...)
b. SRI's NIC-->NSI --> ICANN(IANA) / (NSI->
Verisign) / ARIN
c. Approves registries and registrars (EPP,DNS,whois)
d. Oversee TLDs, root DNS servers (13), IP assignment,
ASN(s) (for BGP between seperate networks)
e. gTLD and ccTLD, and ...New generic TLD(s) .... a
new era...
i. current TLDs http:// www.iana.
org/domains/root/db
●
8. Todays Organizations
● ARIN - American Registry for Internet
Numbers
a. oversee IPs, ASNs, WHOIS, Reverse DNS
b. one of 5 RIR (Regional Internet Registries)
● IANA - Internet Assigned Numbers
Authority
a. Ran by ICANN
i. manages DNS root servers and .int, .arpa
domains TLDs
ii. manages global IPs and ASNs to individual RIRs
like ARIN
iii. Protocol Assignments (which
sockets/ports/services)
9. DNS (Domain Name
System)
DNS
○ Map Names to IPs (forward map), and IPs to Names
(reverse mapping)
○ With Millions of servers(hosts), unreliable networks,
servers, no SPOFs -- how do we do it.
■ Delegation / Authorization
● hierarchical sctructure of data (zones) , any zone can be
Delegated. This is a Tree structure of data.
● Root Level Zones (historically gTLD & ccTLD...)
●
●
10. DNS (Domain Name
System)
DNS
● Authoritative DNS
○ each Domain must have authoritative HOST who is
the master in terms of lookups
■ Any level (or zone) can be delegated to another
host.
■ The top level is called the root level or zone ( each
TLD zone is delegated to a registrar (as defined
by ICANN for each gTLD, and to a country for
each ccTLD) see http:// www.iana.
org/domains/root/db
●
11. DNS (Domain Name
System)
● DNS port 53 (UDP 1st, TCP/Ip port failback)
● DNS DATA and RecordTypes
○ SOA - Start of Authority Record
name ttl class rr name-server email-addr (sn ref ret ex min)
example.com. IN SOA ns.example.com. hostmaster.example.com. (
2003080800 ; sn = serial number
172800 ; ref = refresh = 2d
900 ; ret = update retry = 15m
1209600 ; ex = expiry = 2w
3600 ; min = minimum = 1h
)
; the following are also valid using @ and blank
@ IN SOA ns.example.com. hostmaster.example.com. (
IN SOA ns.example.com. hostmaster.example.com. (
●
●
12. DNS (Domain Name
System)
● NS - Name Server
; zone file fragment for example.com
$TTL 2d ; zone TTL default = 2 days or 172800 seconds
$ORIGIN example.com.
@ IN SOA ns.example.com. hostmaster.example.com. (
2003080800 ; serial number
1d12h ; refresh = 1 day 12 hours
15M ; update retry = 15 minutes
3W12h ; expiry = 3 weeks + 12 hours
2h20M ; minimum = 2 hours + 20 minutes
)
IN NS ns.example.com.
IN NS ns.example.net.
...
; A record for ns.example.com. RR above
ns IN A 192.168.2.1
; the above could have been written as
; ns.example.com. IN A 192.168.2.1
; ns.example.net is out-of-zone (or out-of-bailiwick)
; an A RRs is not required (and will be rejected if present)
○ NS - Name Server
name ttl class rr name
example.com. IN NS ns1.example.com.
; the in-zone name server(s) have an A record
ns1 IN A 192.168.0.3
ns2 IN A 192.168.0.3
; name servers not in zone - no A records required
IN NS ns1.example.net.
IN NS ns1.example.org.
●
●
13. DNS (Domain Name
System)
● A - Address (IPv4)
; zone fragment for example.com
$TTL 2d ; zone default = 2 days or 172800 seconds
joe IN A 192.168.0.3 ; joe & www = same ip
www IN A 192.168.0.3
; functionally the same as the record above
www.example.com. A 192.168.0.3
fred 3600 IN A 192.168.0.4 ; ttl overrides $TTL default
ftp IN A 192.168.0.24 ; round robin with next
● AAA - Address (Ipv60
; zone fragment for example.com
$TTL 2d ; zone default = 2 days or 172800 seconds
$ORIGIN example.com.
....
joe IN AAAA 2001:db8::3 ; joe & www = same ip
www IN AAAA 2001:db8::3
; functionally the same as the record above
www.example.com. AAAA 2001:db8::3
fred 3600 IN AAAA 2001:db8::4 ; ttl =3600 overrides $TTL default
ftp IN AAAA 2001:db8::5 ; round robin with next
IN AAAA 2001:db8::6
mail IN AAAA 2001:db8::7 ; mail = round robin
mail IN AAAA 2001:db8::32
mail IN AAAA 2001:db8::33
●
14. DNS (Domain Name
System)
● MX - Mail eXchanger
name ttl class rr pref name
example.com. IN MX 10 mail.example.com.
IN MX 10 mail ; short form
; the line above is functionally the same as the line below
; example.com. IN MX 10 mail.example.com.
; any number of mail servers may be defined
IN MX 20 mail2.example.com.
; use an external back-up
IN MX 30 mail.example.net.
○ PTR - Pointer (reverse -- opposite of A record)
name ttl class rr name
15 IN PTR www.example.com.
$TTL 2d ; 172800 secs
$ORIGIN 23.168.192.IN-ADDR.ARPA.
; 2 below is actually an unqualified name and becomes
; 2.23.168.192.IN-ADDR.ARPA.
2 IN PTR joe.example.com. ; FDQN
....
15 IN PTR www.example.com.
....
$ORIGIN 0.0.0.0.8.b.d.0.1.0.0.2.IP6.ARPA.
; the second name servers is
; external to this zone (domain).
IN NS ns2.example.net.
; PTR RR maps a IPv6 address to a host name
; hosts in subnet ID 1
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.1.0.0.0 IN PTR ns1.example.com.
●
15. DNS (Domain Name
System)
● CNAME - aliase or realname mapped to Canocial Name
$ORIGIN example.com.
....
server1 IN A 192.168.0.3
www IN CNAME server1
ftp IN CNAME server1
○ TXT - text
○ other special cases (
■ TTL on data, and via client server DNS software
■ DNS Caching (at client, at hosts, .... recursive in
nature)
■ Recursive lookups
■ DNS format types
●
16. DNS (Domain Name
System)
-- special cases
○ TXT - text
○ other special cases (
■ TTL on data, and via client server DNS software
■ DNS Caching (at client, at hosts, .... recursive in
nature)
■ Recursive lookups
■ TSEC, notify, txfr, ...
●
●
18. Whois (DB lookups for
Domains / IPs /....)
● whois -- system for Domains and IPs
○ simple telnet TCP/IP for data using authoritative
server
● examples
○ whois webhero.com
○ whois billmiller.tel
○ whois 204.215.60.0
■ whois -h whois.arin.net NET-204-215-60-0-1
19. DNS config / tools
● DNS config (*nix)
○ /etc/resolv.conf -- specify DNS servers
○ /etc/nsswitch.conf -- order of DNS lookup (files,db,
DNS)
○ /etc/hosts -- flat file of hardcoded DNS lookups
● DNS Server S/w
○ BIND
○ djbdns / tinydns -- by D. J. Bernstien
20. DNS config / tools
● DNS Tools ( and live examples)
○ nslookup
○ host
bill$ host www.allplayers.com
www.allplayers.com has address 174.129.39.74
bill$ host 209.217.1.2
2.1.217.209.in-addr.arpa domain name pointer ns1.catalog.com.
○ dig
○ web-based ... (iptools.com, www.intodns.com, ...)