Transcript SNMP Message - WordPress.com

SNMP & MIME
Rizwan Rehman, CCS, DU
What is Network
Management?
Basic tasks that fall under this category are:
•Configuration Management
•Keeping track of device settings and how they function
•Fault Management
•Dealing with problems and emergencies in the network
(router stops routing, server loses power, etc.)
•Performance Management
•How smoothly is the network running?
•Can it handle the workload it currently has?
Network Management must
be...
The management interface must be...
•Standardized
•Extendible
•Portable
The management mechanism must be...
•Inexpensive
•Implemented as software only
Versions
•Two major versions SNMPv1, SNMPv2
•SNMPv1 is the recommended standard
•SNMPv2 has become split into:
•SNMPv2u - SNMPv2 with user-based security
•SNMPv2* - SNMPv2 with user-based security and additional features
•SNMPv2c - SNMPv2 without security
What is SNMP?
• SNMP is a tool (protocol) that allows for remote
and local management of items on the network
including servers, workstations, routers, switches
and other managed devices.
• Comprised of agents and managers
•Agent - process running on each managed node collecting
information about the device it is running on.
•Manager - process running on a management workstation that
requests information about devices on the network.
Advantages of using SNMP
•
•
•
•
•
•
Standardized
universally supported
extendible
portable
allows distributed management access
lightweight protocol
Client Pull & Server Push
• SNMP is a “client pull” model
The management system (client) “pulls” data from
the agent (server).
• SNMP is a “server push” model
The agent (server) “pushes” out a trap message to a
(client) management system
SNMP & The OSI Model
7
A p p lic a tio n L a ye r
M a n a g e m e n t a n d A g e n t A P Is
SNMP
6 P re s e n ta tio n L a ye r
A S N .1 a n d B E R
5
S e s s io n L a ye r
R P C a n d N e tB IO S
4
T ra n s p o rt L a ye r
TCP and UD P
3
N e tw o rk L a ye r
IP a n d IP X
2
D a ta L in k L a ye r
E th e rn e t, T o k e n R in g , F D D I
1
P h ys ic a l L a ye r
Ports & UDP
•SNMP uses User Datagram Protocol (UDP) as the
transport mechanism for SNMP messages
Ethernet
Frame
IP
Packet
UDP
Datagram
SNMP Message
CRC
•Like FTP, SNMP uses two well-known ports to operate:
•UDP Port 161 - SNMP Messages
•UDP Port 162 - SNMP Trap Messages
The Three Parts of SNMP
SNMP network management is based on three parts:
•SNMP Protocol
•Defines format of messages exchanged by management
systems and agents.
•Specifies the Get, GetNext, Set, and Trap operations
•Structure of Management Information (SMI)
•Rules specifying the format used to define objects managed
on the network that the SNMP protocol accesses
•Management Information Base (MIB)
•A map of the hierarchical order of all managed objects and
how they are accessed
Definition of MIME
“MIME, stand for Multi-purpose Internet mail
Extensions, is a freely available specification that
offers a way to interchange text in languages with
different character sets, and multimedia e-mail
among many different computer system that use
Internet mail standards. ”
Introduction
MIME extends the format of Internet mail to allow nonUS-ASCII textual messages, non-textual messages,
multipart message bodies, and non-US-ASCII
information in message headers.
MIME provides Internet mail users with functionality
similar to that of MS-Mail for LAN-based internal mail.
MS-Mail and MIME allow the attachment of files and
other objects, as does MIME. Unfortunately,
Microsoft’s method of handling these attachments is
undertaken through a proprietary format and MS-Mail
does not provide compliance with the MIME open
standard.
Cont……
Internet messages with MIME attachments send to MSMail will transfer the appropriate text portions of the
message, but MS-Mail will generally forward the
attachments as encoded text, which may then be
saved to a file and decoded. Conversely, messages
sent from MS-Mail with attachments to an Internet
MIME mail system will transfer the text portions and
send the attachments as encoding text, but use a
different method of encoding from the used by MIME
and without the information needed for processing the
message attachment by the recipient. Email messages
arriving at the National Library with MIME attachments
are likely to be corrupted.
What exactly is MIME?
• In 1992, a new standard was defined by an
Internet engineering task force working group in
RFC1521 & 1522 called MIME.
• MIME is an extension to the Internet mail standard,
known as Simple Mail Transfer Protocol (SMTP)
that allows mail messages containing different
type of multimedia information to be sent across
the network this includes, but is not limited to,
word-processor documents, spreadsheets,
programs, graphics, audio, and motion picture
files, as well as links that enable users to retrieve
information from remote databases from within a
mail message.
Cont…
• MIME is a specification for enhancing the
capabilities of standard Internet e-mail.
• It offers a simple standardized way to represent
and encode a wide variety of media types of
transmission via Internet mail.
• It is defines extensions to SMTP to support
binary attachments of arbitrary format.
• The designers of MIME have learned a lot from
the old SMTP protocol and its mailers.
• MIME is here to stay and it works.
Cont…
When using the MIME standard, messages can
contain the following types:
• Text message in US-ASCII
• Character set other than US-ASCII
• Multiple objects in a single messages
• Multimedia; Image, Audio, and Video messages
• Multi-front messages
• Messages of unlimited length
• Binary files
Summary
• MIME has been designed to avoid problems
caused by additional restrictions imposed by
some Internet mail transport mechanisms.
• The Multipart and Message content types allow
mixing and hierarchical structuring of objects of
different types in a single message. Further
content types provide a mechanism for tagging
messages or body parts as audio, image, or
other kinds of data.
• Finally, a number of useful content types are
defined for general use by consenting user
agents, notably Text/Richtext, Message/Partial,
and Message/External-Body.