1. SNMP n Where did it come from ? –Internet Engineering Task Force »Network Management Area –SNMP V1 –MIB definitions –SNMPV2

2. Syntax n uses ASN.1 (Abstract Syntax Notation) –binary encoding 02 01 06is a 1 byte integer, value 6 n Primitive Types INTEGER, OCTECT STRING, OBJECT IDENTIFIER, NULL n Constructor Types SEQUENCE...ie. a record SEQUENCE OF...ie. an array

3. Syntax n Defined Data Types IpAddresswhat you expect Counternon-negative integer that wraps Gaugenon-negative integer that latches TimeTickstime in hundredths of seconds

4. SNMP NAMES

5. SNMP n Management Information Base (MIB) –"database"of network objects –Groups: »System, Interfaces, Address Translation, IP, ICMP, TCP, UDP, EGP –"Access" and "Status" attributes –actual variables are "instances" of OIDs 1.3.6.1.2.1.1.1.0sysDescr 1.3.6.1.2.1.2.1.1.10.3ifInOctets for interface 3 1.3.6.1.2.1.4.21.1.7.130.56.0.0 ipRouteNextHop for network 130.56.0.0

6. SNMP n The SNMP protocol itself –allows inspection and alteration of MIB variables n UDP Based –not acknowledged transactions n PUT, GET, GET-NEXT operators

7. SNMPv1 Protocol continued... Manager Agent get_request get_next_request get_response port 161 port 162 get_response set_request trap

8. SNMPv1 Packet Format UDP Header VersionCommunity PDU Type Request ID Error Status Error Index namevaluename...

9. SNMP n SNMP Traps –unsolicited notification of events –can include variable list –ColdStart, WarmStart –LinkUp, LinkDown –Authentication Failure –EGP Neighbour Loss –Enterprise Specific

10. Network Management Software n SNMP Agents –provided by all router vendors –many expanded (enterprise) MIBs –bridges, wiring concentrators, toasters

11. Network Management Software n Public Domain –Application Programming Interfaces available from CMU and MIT –include variety of applications

12. Network Management Software n Commercially –many offerings, UNIX and PC based »HP OpenView »SunNet Manager »Cabletron Spectrum »*MANY* others

13. Applications

14. Sending MTA Receiving MTA Open TCP connection on port 25 220 ***** [id, ready, time] Hello name 250 [id, Hello pleased to meet….] Mail From: source_name@yahoo.com 250 source_name@yahoo.com Sender OK RCPT To: receiver_name@hotmail.com 250 receiver_name@hotmail.com Recipient OK DATA 354 Mail goes here, end with a “.” line ……………. “.” 250 Mail Accepted QUIT 221 Delivering Mail

16. POP Client POP Mail Server / Local MTA n Example of mail retrieval using POP USER joe_bloggs +OK joe_bloggs PASS mypassword +OK joe_bloggs has 10 messages RETR 1 +OK msg 1 (100 bytes) From: …… Subject: Last week of lectures…… ……………. DELE 1 +OK ………. QUIT +OK ………...

17. Network Address Translation (NAT)

18. NAT Internet NAT router station C station B station A station D IP :10.2.2.1 IP :10.3.3.1 Interface E1 IP :10.1.1.1 Interface E0 IP :171.69.20.1 InsideOutside IP :171.69.2.1 IP :171.69.3.1 NAT Pool 171.69.89.1 protocol TCP Inside source Address : port Outside source Address : port Outside Destination Address : port 10.2.2.1:1024 103.3.1:1723171.69.89.1:1723 171.69.89.1:1024171.69.2.1:23 171.69.3.1:23 NAT Table