Proxy Server PROXY SERVER

What is a Web Proxy? Proxy Server A proxy is a host which relays web access requests from clients Used when clients do not access the web directly Used for security, logging, accounting and performance browserproxy web

What is Web Caching? Storing copies of recently accessed web pages Pages are delivered from the cache when requested again Browser caches Proxy caches Proxy Server

Why Cache? Shorter response time Reduced bandwidth requirement Reduced load on servers Access control and logging Proxy Server

Popular Proxy Caches Apache proxy MS proxy server WinProxy Squid Squid is popular because it is powerful, configurable and free Many others Proxy Server

Squid Setup SQUID SETUP

Obtaining Squid Squid Setup Source code (in C) from Binary executables Linux (comes with RedHat and others) FreeBSD Windows Pre-installed in Fedora/Enterprise Linux

Basic Settings Squid Setup Edit the /etc/squid/squid.conf file to configure squid Configuration options: Disk Cache size and location Authentication Allowed Hosts Any other access restrictions (sites, content, size, time of access etc.) using ACL service squid start/stop/restart

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Mail Architecture Internet Mail Server Mail Client

Mail Architecture

Mail Architecture Simple Mail Transfer Protocol (SMTP) is used to transfer mail between Mail Servers over Internet Post Office Protocol (PoP) and Interactive Mail Access Protocol (IMAP) is used between Client and Mail Server to retrieve mails The mail server of a domain is identified by the MX record of that domain Popular Mail Servers Sendmail/Postfix Microsoft Exchange Server IBM Lotus

Sendmail Setup SENDMAIL SETUP

Sendmail Configuration Mail Server Setup Daemon: sendmail Configuration File: /etc/mail/sendmail.mc Edit the following lines LOCAL_DOMAIN(`localhost.localdomain')dnl (Replace localhost.localdomain by the domain name for which the mail server is being configured) DAEMON_OPTIONS(`Port=smtp,Addr= , Name=MTA')dnl (comment this line by adding dnl at the start of the line) dnl MASQUERADE_AS(`mydomain.com')dnl (remove dnl & replace mydomain.com by the domain name)

Sendmail Configuration Sendmail Setup Add the range of IP addresses of your network in access file (e.g Relay) Run “make –C /etc/mail” command to compile sendmail.mc and generate sendmail.cf file. Restart sendmail and watch for errors

PoP & IMAP Server Sendmail Setup PoP3 & IMAP Server can be started using dovecot server. (service dovecot start)

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VoIP VoIP APPLICATIONS

What is VoIP The packetization and transport of classic public switched telephone system audio over an IP network. The analog audio stream is encoded in a digital format, with possible compression, and encapsulated in IP for transport over your LAN/WAN or the public Internet Modes of Operation: - PC to PC - PC to Telephone - Telephone to PC - Telephone to Telephone VoIP

VoIP Protocols H.323 (ITU-T) SIP (IETF) VoIP

H.323 Architecture VoIP H.323 Terminal Gateway Gatekeeper Multipoint Control Units (MCU)

SIP SIP is a text-based protocol similar to HTTP and SMTP, for initiating interactive communication sessions between users SIP is an application-layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants SIP can be used with different transport protocols, it doesn't even require reliable transport protocols A simple SIP client can be implemented using only UDP VoIP

SIP Architecture VoIP

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