SNMP & MIME

1. SNMP & MIME Rizwan Rehman, CCS, DU

2. Fault Management • Configuration Management • Dealing with problems and emergencies in the network (router stops routing, server loses power, etc.) • Keeping track of device settings and how they function • Performance Management • How smoothly is the network running? • Can it handle the workload it currently has? What is Network Management? Basic tasks that fall under this category are:

3. Network Management must be... The management interface must be... • Standardized • Extendible • Portable The management mechanism must be... • Inexpensive • Implemented as software only

4. 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

5. 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.

6. Advantages of using SNMP • Standardized • universally supported • extendible • portable • allows distributed management access • lightweight protocol

7. 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

8. SNMP & The OSI Model

9. Ports & UDP • SNMP uses User Datagram Protocol (UDP) as the transport mechanism for SNMP messages EthernetFrame IP Packet SNMP Message CRC UDP Datagram • Like FTP, SNMP uses two well-known ports to operate: • UDP Port 161 - SNMP Messages • UDP Port 162 - SNMP Trap Messages

10. 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

11. 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. ”

12. Introduction MIME extends the format of Internet mail to allow non-US-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.

13. Cont…… Internet messages with MIME attachments send to MS-Mail 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.

14. 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.

15. 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.

16. 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

17. 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.