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190 lines
6.4 KiB
Plaintext
190 lines
6.4 KiB
Plaintext
@node SNMP Support
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@chapter SNMP Support
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@acronym{SNMP,Simple Network Managing Protocol} is a widely implemented
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feature for collecting network information from router and/or host.
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Frr itself does not support SNMP agent (server daemon) functionality
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but is able to connect to a SNMP agent using the SMUX protocol
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(@cite{RFC1227}) or the AgentX protocol (@cite{RFC2741}) and make the
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routing protocol MIBs available through it.
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Note that SNMP Support needs to be enabled at compile-time and loaded as
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module on daemon startup. Refer to @ref{Loadable Module Support} on
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the latter.
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@menu
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* Getting and installing an SNMP agent::
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* AgentX configuration::
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* SMUX configuration::
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* MIB and command reference::
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* Handling SNMP Traps::
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@end menu
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@node Getting and installing an SNMP agent
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@section Getting and installing an SNMP agent
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There are several SNMP agent which support SMUX or AgentX. We recommend to use the latest
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version of @code{net-snmp} which was formerly known as @code{ucd-snmp}.
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It is free and open software and available at @uref{http://www.net-snmp.org/}
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and as binary package for most Linux distributions.
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@code{net-snmp} has to be compiled with @code{--with-mib-modules=agentx} to
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be able to accept connections from Frr using AgentX protocol or with
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@code{--with-mib-modules=smux} to use SMUX protocol.
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Nowadays, SMUX is a legacy protocol. The AgentX protocol should be
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preferred for any new deployment. Both protocols have the same coverage.
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@node AgentX configuration
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@section AgentX configuration
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To enable AgentX protocol support, Frr must have been build with the
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@code{--enable-snmp} or @code{--enable-snmp=agentx} option. Both the
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master SNMP agent (snmpd) and each of the Frr daemons must be
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configured. In @code{/etc/snmp/snmpd.conf}, @code{master agentx}
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directive should be added. In each of the Frr daemons, @code{agentx}
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command will enable AgentX support.
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@example
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/etc/snmp/snmpd.conf:
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#
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# example access restrictions setup
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#
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com2sec readonly default public
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group MyROGroup v1 readonly
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view all included .1 80
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access MyROGroup "" any noauth exact all none none
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#
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# enable master agent for AgentX subagents
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#
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master agentx
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/etc/frr/ospfd.conf:
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! ... the rest of ospfd.conf has been omitted for clarity ...
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!
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agentx
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!
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@end example
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Upon successful connection, you should get something like this in the
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log of each Frr daemons:
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@example
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2012/05/25 11:39:08 ZEBRA: snmp[info]: NET-SNMP version 5.4.3 AgentX subagent connected
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@end example
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Then, you can use the following command to check everything works as expected:
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@example
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# snmpwalk -c public -v1 localhost .1.3.6.1.2.1.14.1.1
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OSPF-MIB::ospfRouterId.0 = IpAddress: 192.168.42.109
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[...]
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@end example
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The AgentX protocol can be transported over a Unix socket or using TCP
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or UDP. It usually defaults to a Unix socket and depends on how NetSNMP
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was built. If need to configure Frr to use another transport, you can
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configure it through @code{/etc/snmp/frr.conf}:
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@example
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/etc/snmp/frr.conf:
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[snmpd]
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# Use a remote master agent
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agentXSocket tcp:192.168.15.12:705
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@end example
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@node SMUX configuration
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@section SMUX configuration
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To enable SMUX protocol support, Frr must have been build with the
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@code{--enable-snmp=smux} option.
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A separate connection has then to be established between the
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SNMP agent (snmpd) and each of the Frr daemons. This connections
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each use different OID numbers and passwords. Be aware that this OID
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number is not the one that is used in queries by clients, it is solely
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used for the intercommunication of the daemons.
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In the following example the ospfd daemon will be connected to the
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snmpd daemon using the password "frr_ospfd". For testing it is
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recommending to take exactly the below snmpd.conf as wrong access
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restrictions can be hard to debug.
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@example
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/etc/snmp/snmpd.conf:
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#
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# example access restrictions setup
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#
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com2sec readonly default public
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group MyROGroup v1 readonly
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view all included .1 80
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access MyROGroup "" any noauth exact all none none
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#
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# the following line is relevant for Frr
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#
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smuxpeer .1.3.6.1.4.1.3317.1.2.5 frr_ospfd
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/etc/frr/ospf:
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! ... the rest of ospfd.conf has been omitted for clarity ...
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!
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smux peer .1.3.6.1.4.1.3317.1.2.5 frr_ospfd
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!
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@end example
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After restarting snmpd and frr, a successful connection can be verified in
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the syslog and by querying the SNMP daemon:
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@example
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snmpd[12300]: [smux_accept] accepted fd 12 from 127.0.0.1:36255
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snmpd[12300]: accepted smux peer: \
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oid GNOME-PRODUCT-ZEBRA-MIB::ospfd, frr-0.96.5
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# snmpwalk -c public -v1 localhost .1.3.6.1.2.1.14.1.1
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OSPF-MIB::ospfRouterId.0 = IpAddress: 192.168.42.109
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@end example
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Be warned that the current version (5.1.1) of the Net-SNMP daemon writes a line
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for every SNMP connect to the syslog which can lead to enormous log file sizes.
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If that is a problem you should consider to patch snmpd and comment out the
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troublesome @code{snmp_log()} line in the function
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@code{netsnmp_agent_check_packet()} in @code{agent/snmp_agent.c}.
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@node MIB and command reference
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@section MIB and command reference
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The following OID numbers are used for the interprocess communication of snmpd and
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the Frr daemons with SMUX only.
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@example
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(OIDs below .iso.org.dod.internet.private.enterprises)
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zebra .1.3.6.1.4.1.3317.1.2.1 .gnome.gnomeProducts.zebra.zserv
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bgpd .1.3.6.1.4.1.3317.1.2.2 .gnome.gnomeProducts.zebra.bgpd
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ripd .1.3.6.1.4.1.3317.1.2.3 .gnome.gnomeProducts.zebra.ripd
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ospfd .1.3.6.1.4.1.3317.1.2.5 .gnome.gnomeProducts.zebra.ospfd
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ospf6d .1.3.6.1.4.1.3317.1.2.6 .gnome.gnomeProducts.zebra.ospf6d
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@end example
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Sadly, SNMP has not been implemented in all daemons yet. The following
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OID numbers are used for querying the SNMP daemon by a client:
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@example
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zebra .1.3.6.1.2.1.4.24 .iso.org.dot.internet.mgmt.mib-2.ip.ipForward
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ospfd .1.3.6.1.2.1.14 .iso.org.dot.internet.mgmt.mib-2.ospf
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bgpd .1.3.6.1.2.1.15 .iso.org.dot.internet.mgmt.mib-2.bgp
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ripd .1.3.6.1.2.1.23 .iso.org.dot.internet.mgmt.mib-2.rip2
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ospf6d .1.3.6.1.3.102 .iso.org.dod.internet.experimental.ospfv3
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@end example
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The following syntax is understood by the Frr daemons for configuring SNMP using SMUX:
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@deffn {Command} {smux peer @var{oid}} {}
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@deffnx {Command} {no smux peer @var{oid}} {}
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@end deffn
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@deffn {Command} {smux peer @var{oid} @var{password}} {}
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@deffnx {Command} {no smux peer @var{oid} @var{password}} {}
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@end deffn
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Here is the syntax for using AgentX:
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@deffn {Command} {agentx} {}
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@deffnx {Command} {no agentx} {}
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@end deffn
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@include snmptrap.texi
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