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

Syntax n uses ASN.1 (Abstract Syntax Notation) –binary encoding is 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

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

SNMP NAMES

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 sysDescr ifInOctets for interface ipRouteNextHop for network

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

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

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

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

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

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

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

Applications

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

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 ………...

Network Address Translation (NAT)

NAT Internet NAT router station C station B station A station D IP : IP : Interface E1 IP : Interface E0 IP : InsideOutside IP : IP : NAT Pool protocol TCP Inside source Address : port Outside source Address : port Outside Destination Address : port : : : : : :23 NAT Table