DHCP

The current network architecture for mobile devices presents applications with a synchronous model and employs end-to-end connections. In reality, devices are often disconnected from the network and, while they are disconnected, they can connect to other devices in the neighborhood and exploit the connectivity to allow the user to continue to work. This is the key concept of the Haggle project [1], a groundup redesign of networking for mobile devices, to support the mobile user scenario. In order to benefit from users mobility, it is necessary to be able to opportunistically switch between (ad hoc) connections, whenever a new opportunity of connection arises. This imposes that connection set-up time must be minimal, considering that the nodes will probably stay in the range of each other for a short time frame. However, we saw that the 802.11 connectivity in Haggle carries significant overhead (especially when switching between Access Point (AP) mode and ad hoc mode, particularly wh...

This document is the core of my work regarding our network project.
The essential objective of this document is to design and implement IP network of a company.
During my work, the first mission was to realize comparative analysis to look for the most suitable type of cable to construct an adequate network for the whole company building. Then, i realize also a comparative study to choose the right switch and router to set up the LAN architecture building located in Casablanca, then the WAN architecture that is located between Casablanca and Rabat, and Finally I reinforced my architecture using multiple security protocols, all this work is represented with PACKET TRACER software.
Keywords: cabling, LAN, WAN, security, PACKET TRACER…

Yasal sorumluklardan dolayı ve güvenlik analizleri için ağ yöneticilerine, belirli tarihte bir IP adresini kimin kullandığı sorusu sık sık sorulur.  Eğer bütün kullanıcılar bir hotpot/Proxy/Captive Portal kullanılıyorsa bu soruya cevap vermek kolaydır. Ama kullanılmayan durumlarda diğer yöntemlerden faydalanmak gerekir. Burada 802.1x Ağ Kimlik Denetimi Protokolü ve MAC adresi temelli kimlik denetimi devreye girer. 802.1x kimlik denetimi protokolü OSI’ye göre ikinci katman protokolüdür ve oluşan logda sadece MAC bilgisi bulunur dolayısı ile başka bir networke taşınmaz ayrıca soru IP adresini kim kullandı şeklindedir. MAC adresi temelli kimlik denetimi ise pratikte uygulaması imkansızdır. Mesela MAC adresi değiştiren programlar vs.. . Bu durumda MAC ve IP arasındaki ilişkileri her durumda alıp otomatik korelasyona tabi tutan bir sistem gerekmektedir. Bunun da yolu DHCP Sunucu loğları ile gatewaylerdeki ARP tablosunu takip edip sonuçları korele etmektir.

Em uma rede IP, antes que os dispositivos possam se comunicar, eles precisam ter seus próprios endereços IP. Há duas maneiras de configurar um endereço IP em um dispositivo:

 Atribuir estaticamente um endereço IP. Isso significa, digitar manualmente um endereço IP para este computador
 Usar um protocolo para que o computador possa obter seu endereço IP automaticamente (dinamicamente). O protocolo mais popular hoje em dia para fazer esta tarefa é chamado DHCP (Dynamic Host Configuration Protocol) e vamos aprender mais sobre o DHCP neste laboratório.

Uma grande vantagem de usar DHCP é a capacidade de ingressar em uma rede sem saber detalhes sobre ela. Por exemplo, você vai a uma cafeteria, com DHCP ativado em seu computador, você pode entrar online sem fazer nada.
No dia seguinte você entra online na sua faculdade e você não precisa configurar nada, mesmo que as redes da cafeteria e sua faculdade sejam diferentes (por exemplo, a rede da cafeteria é 192.168.1.0/24 enquanto a de sua faculdade é 10.0.0.0/8). Muito legal, certo? Sem DHCP, você tem que perguntar a alguém que sabe sobre as redes em seu local, em seguida, configurar manualmente um endereço IP nesse intervalo.

Uma situação perigosa é que o IP escolhido pode ser o mesmo que alguém já esteja usando nessa rede e um conflito de endereço pode ocorrer. Então, como DHCP pode oferecer um endereço IP adequado para você automaticamente? Vamos descobrir agora!

© 1999-2015 Joel Barrios Dueñas. Usted es libre de copiar, distribuir y comunicar públicamente la obra y hacer obras derivadas bajo las condiciones siguientes: a) Debe reconocer y citar al autor original. b) No puede utilizar esta obra para fines comerciales. c) Si altera o transforma esta obra o genera una obra derivada, sólo puede distribuir la obra generada bajo una licencia idéntica a ésta. Al reutilizar o distribuir la obra, tiene que dejar bien claro los términos de la licencia de esta obra. Alguna de estas condiciones puede no aplicarse si se obtiene el permiso del titular de los derechos de autor. Los derechos derivados de usos legítimos u otras limitaciones no se ven afectados por lo anterior. La información contenida en este documento y los derivados de éste se proporcionan tal cual son y los autores no asumirán responsabilidad alguna si el usuario o lector hace mal uso de éstos.

menghubungkan 3 router dengan menggunakan kabel serial DTE dengan menambah module WIC-2T dan WIC-1T pada router, mengkonfigurasi Router RIP menggunakan CLI, Mengkonfigurasi Router menggunakan CLI, mengkonfigurasi Wireless Router, mengkonfigurasi DNS dan DHCP.

This report covers the basic security protocols such as WEP, WPA and WPA2 used in today's wireless networks, how they work, existing flaws and vulnerability's. Further more we will go through some practical experiment exploiting the flaws described in the article.

Cuando se intenta configurar una red de área local inalámbrica (WLAN) de forma manual con los procedimientos tradicionales más difundidos, se obtiene un fallo crítico que arroja un mensaje «error for wireless request "set encode" (8b2a)» si el punto de acceso inalámbrico
(WAP) protege la red con sistemas WPA o WPA2. Esto, se debe a que los procedimientos tradicionales basan su método de configuración en redes protegidas con el antiguo sistema de protección WEP declarado obsoleto hace más de una década, a raíz de sus conocidas debilidades criptográficas. Este estudio se concentró en entender el funcionamiento exacto de las redes inalámbricas, sus protocolos, sistemas de protección y mecanismos de transmisión de datos, para obtener así, el procedimiento más adecuado para lograr una configuración
propicia cuando se prescinde por completo del entorno gráfico.

Petri Networks with a graphical language are based on mathematical logic which have many uses and have capability for modeling and validation of distributed systems and concurrent applications. Colored Petri Networks (CPNs) are a type of Petri Network models that are used in modeling of systems which contain discrete and scattered events. In general, CPNs are used to evaluate system performance and demonstrate the correctness of systems. Dynamic Host Configuration Protocol (DHCP) is one of the main systems of protocols special for servers that are used for dynamic allocation of IP to the network computers (clients). In this paper, we highlight to analyze the correctness and authenticity of DHCPs with the use of CPNs with using the CPN Tools and to prove the accuracy of our protocol's performance.

Curso ESPECIALISTA LINUX e Segurança em Redes preparatório para as certificações LPI. Administração de Sistemas, Redes e Servidores Linux, Debian, Fedora, Ubuntu, CentOS e FreeBSD. Apache, Samba, NIS, NFS, DHCP, PROXY, SQUID, IPTABLES, FIREWALL, Postfix, LDAP, NMAP, TCPDUMP. Rio de Janeiro -rj

This document addresses numerous security problems which DHCPv6 could be a victim of. We believe DHCPv6 will be the configuration method of choice. Despite of this fact, we think we have to describe a number of security issues one must be aware of in case of using DHCPv6 in an open environment.

This paper introduces a novel method, UDmap, to identify dynamically assigned IP addresses and analyze their dynamics pattern. UDmap is fully automatic, and relies only on application-level server logs that are already available today. We applied UDmap to a month-long Hotmail user-login trace and identified a significant number of dynamic IP addresses -more than 102 million. This suggests that the portion of dynamic IP addresses in the Internet is by no means negligible. In addition, using this information combined with a three-month Hotmail email server log, we were able to establish that 97% of mail servers setup on dynamic IP addresses sent out solely spam emails, likely controlled by zombies. Moreover, these mail servers sent out a large amount of spam -counting towards over 42% of all spam emails to Hotmail. These results highlight the importance of being able to accurately identify dynamic IP addresses for spam filtering, and we expect similar benefits of it for phishing site identification and botnet detection. To our knowledge, this is the first successful attempt to automatically identify and understand IP dynamics.

Cuando se intenta configurar una red de área local inalámbrica (WLAN) de forma manual con los procedimientos tradicionales más difundidos, se obtiene un fallo crítico que arroja un mensaje «error for wireless request "set encode" (8b2a)» si el punto de acceso inalámbrico (WAP) protege la red con sistemas WPA o WPA2. Esto, se debe a que los procedimientos tradicionales basan su método de configuración en redes protegidas con el antiguo sistema de protección WEP declarado obsoleto hace más de una década, a raíz de sus conocidas debilidades criptográficas. Este estudio se concentró en entender el funcionamiento exacto de las redes inalámbricas, sus protocolos, sistemas de protección y mecanismos de transmisión de datos, para obtener así, el procedimiento más adecuado para lograr una configuración propicia cuando se prescinde por completo del entorno gráfico.

This paper introduces a novel method, UDmap, to identify dynamically assigned IP addresses and analyze their dynamics pattern. UDmap is fully automatic, and relies only on application-level server logs that are already available today. We applied UDmap to a month-long Hotmail user-login trace and identified a significant number of dynamic IP addresses -more than 102 million. This suggests that the portion of dynamic IP addresses in the Internet is by no means negligible. In addition, using this information combined with a three-month Hotmail email server log, we were able to establish that 97% of mail servers setup on dynamic IP addresses sent out solely spam emails, likely controlled by zombies. Moreover, these mail servers sent out a large amount of spam -counting towards over 42% of all spam emails to Hotmail. These results highlight the importance of being able to accurately identify dynamic IP addresses for spam filtering, and we expect similar benefits of it for phishing site identification and botnet detection. To our knowledge, this is the first successful attempt to automatically identify and understand IP dynamics.

In Vehicular Ad-hoc Networks (VANETs), vehicles can gain short connections to the Internet by using wireless access points (AP). A significant part of the connection time is the time required for acquiring an IP address via Dynamic Host Configuration Protocol (DHCP). Depending on a vehicle's speed and the AP coverage area, DHCP can consume up to 100 percent of a vehicle's available connection time. We propose the IP Passing Protocol to reduce the overhead of obtaining an IP address to under one-tenth of a second. This is done without modifying either DHCP or AP software. We explore scalable implementations and describe the dynamics of the IP Passing Protocol. We also show our protocol will significantly improve efficiency, reduce latency, and increase vehicle connectivity.

The construction of gigabit switches is an intuitive issue. In fact, few information theo-rists would disagree with the visualization of e-business, which embodies the natural principles of steganography. We disprove that flip-flop gates and the partition table can collaborate to achieve this intent.

A mobile ad hoc network (MANET) is a multi-hop wireless network capable of autonomous operation. The mobility of MANET nodes can lead to frequent and unpredictable topology changes. Most MANET literature assumes that network related information of a node (such as its IP address, netmask, etc.) is configured statically, prior to the node joining the MANET. However, not all nodes have IP addresses permanently assigned to them. Such nodes rely on a centralized server and use a dynamic host configuration protocol, like DHCP [1], to acquire an IP address. Such a solution cannot be employed in MANETs due to the unavailability of any centralized DHCP server. In this paper, we first present a survey of possible solutions approaches, and discuss their limitations. Then, we present a distributed dynamic host configuration protocol designed to configure nodes in a MANET. We show that the proposed protocol works correctly and does not have the limitations of earlier approaches. Finally, we evaluate the performance of the solution through simulation experiments, and conclude with a discussion of related security issues.

Today we can see that there is a lot of growth happening around the world and particularly in the IT sector. A number of start-ups require good networking infrastructure which is good both in terms of reliability as well as network connectivity. A network is nothing but a system of interconnected components in which two or more devices communicate with one another to share a piece of information among them or other devices to which access is available. A network can be small or large ranging from big offices to small labs inside a complex. The main point in all the discussions around the globe is that networking is required in order to communicate from one place to another. This paper demonstrates a perfect blend of both low cost and high throughput which will help new startups to set up their infrastructure particularly for the networking segment at low cost, less latency, and high availability. This paper aims to cover the detailed description and use case scenarios that implement...

oday we can see that there is a lot of growth happening around the world and particularly in the IT sector. A number of start-ups require good networking infrastructure which is good both in terms of reliability as well as network connectivity. A network is nothing but a system of interconnected components in which two or more devices communicate with one another to share a piece of information among them or other devices to which access is available. A network can be small or large ranging from big offices to small labs inside a complex. The main point in all the discussions around the globe is that networking is required in order to communicate from one place to another. This paper demonstrates a perfect blend of both low cost and high throughput which will help new startups to set up their infrastructure particularly for the networking segment at low cost, less latency, and high availability. This paper aims to cover the detailed description and use case scenarios that implement an efficient network topology design for swift data packet transfer and fast scalability for a Small Office or Home Office (SOHO) type infrastructure. This paper has been written by keeping in mind the fact that it fulfills the basic needs required for a SOHO infrastructure. This efficient design will enable plug-and-play type node connectivity for scalability and will be centrally administered as discussed in detail in subsequent sections of the paper.

ABSTRACT-The dynamic host configuration protocol (DHCP) is a widely used communication protocol. In this paper we have chosen a portion of the protocol for verification, namely assignment of new IP address to a newly arriving host. We modeled it ...

Dynamic Host Configuration Protocol (DHCP) is used to automatically configure clients with IP address and other network configuration parameters. Due to absence of any in-built authentication, the protocol is vulnerable to a class of Denial-of-Service (DoS) attacks, popularly known as DHCP starvation attacks. However, known DHCP starvation attacks are either ineffective in wireless networks or not stealthy in some of the network topologies. In this paper, we first propose a stealth DHCP starvation attack which is effective in both wired and wireless networks and can not be detected by known detection mechanisms. We test the effectiveness of proposed attack in both IPv4 and IPv6 networks and show that it can successfully prevent other clients from obtaining IP address, thereby, causing DoS scenario. In order to detect the proposed attack, we also propose a Machine Learning (ML) based anomaly detection framework. In particular, we use some popular one-class classifiers for the detection purpose. We capture IPv4 and IPv6 traffic from a real network with thousands of devices and evaluate the detection capability of different machine learning algorithms. Our experiments show that the machine learning algorithms can detect the attack with high accuracy in both IPv4 and IPv6 networks.

A mobile ad hoc network (MANET) is a multi-hop wireless network capable of autonomous operation. The mobility of MANET nodes can lead to frequent and unpredictable topology changes. Most MANET literature assumes that network related information of a node (such as its IP address, netmask, etc.) is configured statically, prior to the node joining the MANET. However, not all nodes have IP addresses permanently assigned to them. Such nodes rely on a centralized server and use a dynamic host configuration protocol, like DHCP [1], to acquire an IP address. Such a solution cannot be employed in MANETs due to the unavailability of any centralized DHCP server. In this paper, we first present a survey of possible solutions approaches, and discuss their limitations. Then, we present a distributed dynamic host configuration protocol designed to configure nodes in a MANET. We show that the proposed protocol works correctly and does not have the limitations of earlier approaches. Finally, we evaluate the performance of the solution through simulation experiments, and conclude with a discussion of related security issues.