Capa aplicación: Ofrece a las aplicaciones (de usuario o no) la posibilidad de acceder a
los servicios de las demás capas y define los protocolos que utilizan
las aplicaciones para intercambiar datos, como correo electrónico (POP y
SMTP), gestores de bases de datos y protocolos de transferencia de
archivos (FTP).
Capa presentación: Se encarga de la representación de la información, de manera que aunque
distintos equipos puedan tener diferentes representaciones internas de
caracteres (ASCII, Unicode, EBCDIC), números (little-endian tipo Intel, big-endian tipo Motorola), sonido o imágenes, los datos lleguen de manera reconocible. Leer más.
Servicios:
Data conversion: Is the conversion of computer data from one format to another. Throughout a computer environment, data is encoded in a variety of ways. For example, computer hardware is built on the basis of certain standards, which requires that data contains, for example, parity bit checks.Read more.
Compression: Compression is useful because it helps reduce resources usage, such as data storage space or transmission capacity.
Because compressed data must be decompressed to be used, this extra
processing imposes computational or other costs through decompression,
this situation is far from being a free lunch. Read more.
Encryption and Decryption: Is used to protect data in transit, for example data being transferred via networks (e.g. the Internet, e-commerce), mobile telephones, wireless microphones, wireless intercom systems, Bluetooth devices and bank automatic teller machines. Read more.
Protocolos:
Apple Filing Protocol (AFP): Is a proprietary network protocol that offers file services for Mac OS X and original Mac OS. In Mac OS X, AFP is one of several file services supported including Server Message Block (SMB), Network File System (NFS), File Transfer Protocol (FTP), and WebDAV. Read more.
Independent Computing Architecture (ICA), the Citrix system core protocol: Is a proprietary protocol for an application server system, designed by Citrix Systems. The protocol lays down a specification for passing data between server and clients, but is not bound to any one platform. Read more.
NetWare Core Protocol (NCP): Is a network protocol used in some products from Novell, Inc. It is usually associated with the NetWare operating system, but parts of it have been implemented on other platforms such as Linux, Windows NT and various flavors of Unix. Read more.
Telnet: Is a network protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. User data is interspersed in-band with Telnet control information in an 8-bit byte oriented data connection over the Transmission Control Protocol (TCP). Read more.
eXternal Data Representation (XDR): Is a standard data serialization format, for uses such as computer network
protocols. It allows data to be transferred between different kinds of
computer systems. Converting from the local representation to XDR is
called encoding. Read more.
X.25 Packet Assembler/Disassembler Protocol (PAD): An X.25 WAN consists of packet-switching exchange (PSE) nodes as the networking hardware, and leased lines, plain old telephone service connections or ISDN connections as physical links.Read more.
Diagrama de red X25.
CAPA SESION
Capa 5 Modelo OSI "Sesión"
Nivel de sesión: La capa de sesión establece, administra y termina las sesiones entre las aplicaciones. Leer más. The session layer of the OSI model is responsible for session checkpointing
and recovery. It allows information of different streams, perhaps
originating from different sources, to be properly combined or
synchronized.
Aplicaciones:
Conferencia WEB: In which the streams of audio and video must be synchronous to avoid so-called lip synch problems. Floor control ensures that the person displayed on screen is the current speaker.
TV live: Where streams of audio and video need to be seamlessly merged and
transitioned from one to the other to avoid silent airtime or excessive
overlap.
Protocolos:
ADSP (AppleTalk Data Stream Protocol): Is a proprietary suite of networking protocols developed by Apple Inc. for their Mac computers. AppleTalk included a number of features that allowed local area networks to be connected with no prior setup or the need for a centralized router or server of any sort. Read more.
H.245 (Call Control Protocol for Multimedia Communication): Is a control channel protocol used with[in] e.g. H.323 and H.324 communication sessions, and involves the line transmission of non-telephone signals. It also offers the possibility to be tunneled within H.225.0 call signaling messages. This eases firewall traversing. Read more.
iSNS (Internet Storage Name Service): Provides management services similar to those found in Fibre Channel
networks, allowing a standard IP network to operate in much the same way
that a Fibre Channel storage area network does. Read more.
L2F (Layer 2 Forwarding Protocol): Is a tunneling protocol developed by Cisco Systems, Inc. to establish virtual private network connections over the Internet. L2F does not provide encryption or confidentiality by itself; It relies on the protocol being tunneled to provide privacy. L2F was specifically designed to tunnel Point-to-Point Protocol (PPP) traffic. Read more.
NetBIOS (Network Basic Input Output System): It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. Read more.
PAP (Password Authentication Protocol): Is used by Point to Point Protocol to validate users before allowing them access to server resources. Almost all network operating system remote servers support PAP. Read more.
RPC (Remote Procedure Call Protocol): Is an inter-process communication that allows a computer program to cause a subroutine or procedure to execute in another address space
(commonly on another computer on a shared network) without the
programmer explicitly coding the details for this remote interaction. Read more.
RTCP (Real-time Transport Control Protocol): Provides out-of-band statistics and control information for an RTP flow.
It partners RTP in the delivery and packaging of multimedia data, but
does not transport any media streams itself. Read more.
SMPP (Short Message Peer-to-Peer): Is a telecommunications industry protocol for exchanging SMS messages between SMS peer entities such as short message service centers and/or External Short Messaging Entities. It is often used to allow third parties (e.g. value-added service providers like news organizations) to submit messages, often in bulk. Read more.
SOCKS: Is an Internet protocol that routes network packets between a client and server through a proxy server. SOCKS5 additionally provides authentication
so only authorized users may access a server. Practically, a SOCKS
server will proxy TCP connections to an arbitrary IP address as well as
providing a means for UDP packets to be forwarded. Read more.
SDP (Sockets Direct Protocol): The purpose of the Sockets Direct Protocol is to provide an RDMA accelerated alternative to the TCP protocol on IP. The goal is to do this in a manner which is transparent to the application. Read more.
Capa transporte: Encargado de la transferencia libre de errores de los datos entre el emisor y el receptor. Leer más
TCP: El protocolo garantiza que los datos serán entregados en su destino sin
errores y en el mismo orden en que se transmitieron. También
proporciona un mecanismo para distinguir distintas aplicaciones dentro
de una misma máquina, a través del concepto de puerto. Leer más.
UDP: Permite el envío de datagramas a través de la red
sin que se haya establecido previamente una conexión, ya que el propio
datagrama incorpora suficiente información de direccionamiento en su
cabecera. Tampoco tiene confirmación ni control de flujo, por lo que los
paquetes pueden adelantarse unos a otros; y tampoco se sabe si ha
llegado correctamente, ya que no hay confirmación de entrega o
recepción.Leer más
Puertos de red: Es una interfaz para comunicarse con un programa a través de una red. Esta asignación de puertos permite a una máquina establecer
simultáneamente diversas conexiones con máquinas distintas, ya que todos
los paquetes que se reciben tienen la misma dirección, pero van
dirigidos a puertos diferentes. Leer más.
netstat -n: La información que resulta del uso del comando incluye el protocolo en
uso, las tablas de ruteo, las estadísticas de las interfaces y el estado
de la conexión. Muestra un listado de las conexiones activas de una computadora, tanto
entrantes como salientes. Existen versiones de este comando en varios
sistemas como Unix, GNU/Linux, Mac OS X, Windows y BeOS. Leer más.
PNAT: Es un método incluido en el protocolo NAT
para recuperar la dirección IP pública de un gateway NAT, permitiendo
así que un cliente pueda hacer de esta dirección IP pública y del número
de puerto conocido a un par que desee comunicarse con él. Leer más.
Cluster:Se aplica a los conjuntos o conglomerados de computadoras construidos mediante la utilización de hardwares comunes y que se comportan como si fuesen una única computadora.Leer más
Cloud computing: El concepto de la computación en la nube empezó en proveedores de
servicio de Internet a gran escala, como Google, Amazon AWS, Microsoft y
otros que construyeron su propia infraestructura. De entre todos ellos
emergió una arquitectura: un sistema de recursos distribuidos
horizontalmente, introducidos como servicios virtuales de TI escalados
masivamente y manejados como recursos configurados y mancomunados de
manera continua. Leer más.
Servicios en la nube.
Eucalyptus: Is a software platform for the implementation of private cloud computing on computer clusters. It exports a user-facing interface that is compatible with the Amazon EC2 and S3 services, but the platform is modularized so that it can support a set of different interfaces simultaneously. Read more:
Virus informático: Los virus informáticos afectan en mayor o menor medida a casi todos los sistemas más conocidos y usados en la actualidad. Cabe aclarar que un virus informático mayoritariamente atacará sólo el sistema operativo para el que fue desarrollado, aunque ha habido algunos casos de virus multiplataforma. Leer más.
SYN ATTACK: Is a form of denial-of-service attack in which an attacker sends a succession of SYN
requests to a target's system in an attempt to consume enough server
resources to make the system unresponsive to legitimate traffic. Read more.
Internet Engineering Task Force (IETF): The mission of the IETF is to make the Internet work better by producing high quality, relevant technical
documents that influence the way people design, use, and manage the Internet. Read more.
RFC de Apple: Detalla el número del documento solicitud de comentario que define el
servicio o protocolo concreto y que puede usarse como referencia. Algunos servicios pueden utilizar dos o más puertos.Leer más.
Ejemplo: FTP RFC 959: Es la especificación oficial del Protocolo de
Transferencia de Ficheros (File Transfer Protocol, FTP). Con esta especificación se intentan satisfacer las diversas
necesidades de los usuarios de maxi-hosts, mini-hosts, estaciones de
trabajo personales y TAC's con un diseño de protocolo simple y fácil
de programar. Leer más.
Ejemplo: SMTP RFC 821: The objective of Simple Mail Transfer Protocol (SMTP) is to transfer
mail reliably and efficiently. An important feature of SMTP is its capability to relay mail across
transport service environments. Read more.
Ejemplo: ESMTP RFC 1869: The Simple Mail Transfer Protocol (SMTP) has provided a stable,
effective basis for the relay function of message transfer agents.
Although a decade old, SMTP has proven remarkably resilient.
Nevertheless, the need for a number of protocol extensions has become
evident. Rather than describing these extensions as separate and
haphazard entities, this document enhances SMTP in a straightforward
fashion that provides a framework in which all future extensions can
be built in a single consistent way. Read more.
Ejemplo: TELNET RFC 854: El propósito del protocolo TELNET es proporcionar un servicio de
comunicaciones orientado a bytes de 8 bit general y bidireccional.
El principal objetivo es permitir un método estándar de comunicar
entre sí terminales y procesos orientados a terminal. Leer más.
Ejemplo: POP3 RFC 1939: El
Post Office Protocol (N. del T. Protocolo de Oficina de Correos) - Versión
3 (POP3) se utiliza para permitir a una estación de trabajo transferir
el correo que guarda el servidor.
La orientación del protocolo POP3 no es proporcionar amplias operaciones
de de correo en el servidor; normalmente el correo se transfiere y
después se borra.Leer más.
Ejemplo: IMAP4 RFC 1730: The Internet Message Access Protocol, Version 4 (IMAP4) allows a
client to access and manipulate electronic mail messages on a server.
IMAP4 permits manipulation of remote message folders, called
"mailboxes", in a way that is functionally equivalent to local
mailboxes. IMAP4 also provides the capability for an offline client
to resynchronize with the server. Read more.
Ejemplo: HTTP RFC 2616: The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World-Wide Web global
information initiative since 1990. Read more
Squidguard: SquidGuard is a URL redirector used to use blacklists with the
proxysoftware Squid. There
are two big advantages to squidguard: it is fast and it is free.
SquidGuard is published
under GNU Public License.
Read more.
Blacklist: The blacklists are the heart of every URL Filter! You can choose between several free and commercial distributions of
blacklists on the net or create and use your own (or any combination
of them). SquidGuard comes with a small blacklist basically for testing purposes.
In production you don't want to use them. A better way is to start with
one of the blacklist collections listed (alphabetically) below. Read more.
