Download What is Web Caching?

Proxy Server
PROXY SERVER
Proxy Server
What is a Web Proxy?
A proxy is a host which relays web access requests
from clients
Used when clients do not access the web directly
Used for security,
performance
browser
logging,
proxy
accounting
web
and
Proxy Server
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
configurable and free
Many others
it
is
powerful,
Squid Setup
SQUID SETUP
Squid Setup
Obtaining Squid
Source code (in C) from www.squid-cache.org
Binary executables
Linux (comes with RedHat and others)
FreeBSD
Windows
Pre-installed in Fedora/Enterprise Linux
Squid Setup
Basic Settings
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
QUESTIONS?
Email
EMAIL
Email
Mail Architecture
Internet
Mail
Server
Mail Client
Mail
Server
Mail Client
Email
Mail Architecture
Email
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
Mail Server Setup
Sendmail Configuration
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=127.0.0.1,
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 Setup
Sendmail Configuration
Add the range of IP addresses of your network in
access file
(e.g. 172.31.
Relay)
Run “make –C /etc/mail” command to compile
sendmail.mc and generate sendmail.cf file.
Restart sendmail and watch for errors
Sendmail Setup
PoP & IMAP Server
PoP3 & IMAP Server can be started using dovecot
server. (service dovecot start)
QUESTIONS?
VoIP
VoIP APPLICATIONS
VoIP
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
􀂄 H.323 Terminal
􀂄 Gateway
􀂄 Gatekeeper
􀂄 Multipoint Control Units (MCU)
VoIP
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
QUESTIONS?