The Process / Application Layer Protocols

#CCNA #BILZdailywrite

I'll describe the different application and services typically used in IP networks. 

The following protocols and application are covered Telnet

• FTP
• TFTP 
• NFS 
• SMTP
• POP
• IMAP4
• TLS
• SIP (VoIP)
• RTP (VoIP)
• LPD 
• X WINDOW
• SNMP
• SSH
• HTTP
• HTTPS
• NTP
• NNTP
• SCP
• LDAP
• IGMP
• LPR
• DNS
• DHCP / BootP

Telnet - 

Telnet is the chameleon of protocols - its specialty is terminal emulation. it allows a user on a remote client machine. called the Telnet client to access the resources of another machine . telnet achieves this by pulling a fast one on the telnet server and making the client machine appear as though it were a terminal directly attached to the local network. this projection is actually a software- a virtual  terminal that can interact with the chosen remote host. 

File Transfer Protocol (FTP) - 

FTP is the protocols that actually lets us transfer files and it can  accomplish this between any two machine using it. but FTP isn't just a protocols its also a program. operating as a protocol FTP is used by application. as a proogram its employed by users to perform file tasks by hand.

you can get around this somewhat by adopting the username anonymous though what you'll gain  access to will be limited.

Even when employed by users manually as a program FTP functions are limited to listing and manipulating directories typing file contents and copying files between hosts. it can't execute remote files as programs.

Tribial file transfer protocols (TFTP)

TFTP is the stripped down stock version of FTP but is the protocols of choice if you know exactly what you want and where to find it plus its so easy to use and it's fast too it doesn give you the abundance of functions that FTP does files. Few sites support it because of the inherent security risks.

Network file system ( NFS)

NFS is a jewel of a protoco specializing in file sharing. It allows two different type of file system to interoperate. it works like this suppose the NFS server software is running on a windows server and the NFS client software is running on a unix host NFS allows for a portion of the RAM on the Windows server to transparently store Unix files system are unlike they have different case sensitivity file name lengts security and so on both Unix users and Windows users can access that same file with their normal file system in their normal way.

Simple Mail Transfer Protocol (SMTP )

SMTP answering our ubiquitous call to email, uses a spooled or queued method of mail delivery. once a message has been sent to a destination the message is spooled to a device usually a disk. the server software at the destination posts a vigil regularly checking the queue for messages. when it detects them it proceds to deliver them to their destination. 

Post office protocol ( POP)

POP gives us a  storage facility for incoming mail and the latest version is called POP3 basically how this protocol works is when a client device connects to a  POP3 server messages addressed to that client are released for downloading. 

Internet Message Access Protocol Version 4 ( IMAP4)

IMAP makes it so you get control over how you download you mail and with it you also gain some much needed security it lets you peek at the message header or download just a part of a message you can now just nibble at the bait instead of swallowing it  whole and then choking on the hook hidden inside.

you can choose to store messages on the email server hierarchically and link to documents and user groups too. IMAP even gives you search commands to use to hunt for messages based on their subject header or content. as you can imagine it has some serious authentication features it actually supports the kerberos authentication scheme that.

Transport Layer Security (TLS)

TLS and it s forerunner secure sockets layer ( SSL) are cryptographic protocol that come in really handy for enabling secure online data transfer activities like browsing the web instant messaging, internet faxing and so on. they re so similar it not within the scope of this book to detail the differences between them.

Session Initiation protoco  ( SIP ) 

 A hugely popular signaling protocol used to construct and deconstruct multimedia communication sessions for many things like voice and video calls video conferring streaming multimedia distribution instant messaging presence information and online games over the internet.

Real Time Transport Protocol ( RTP (VoIP )) 

describes a packet formatting standard for delivering audio and video over the internet althought initially designed as a multicast protocol it now used for unicast application too. it commonly employed for streaming media video conferencing and push to talk systems all things that make it a de facto standard in voice over IP industries. 

Line Printer Daemon  ( LPD)

LPD protocol is designed for printer sharing the LPD along with the line printer program. allows print jobs to be spooled and sent to the network printers using TCP / IP