.TH SNMPD.CONF 5 "08 Feb 2002" VVERSIONINFO "Net-SNMP"
.UC 4
.SH NAME
snmpd.conf - configuration file for the Net-SNMP SNMP agent
.SH DESCRIPTION
.B snmpd.conf
is the configuration file which defines how the Net-SNMP SNMP agent
operates.  These files may contain any of the directives found in the
.B DIRECTIVES
section below.  If this file is not found (or does not contain any
access control directives), the agent will run but will not respond
to any requests.
.SH PLEASE READ FIRST
First, make sure you have read the
.I snmp_config(5) 
manual page that describes how the Net-SNMP configuration files
operate, where they are located and how they all work together.
.PP
Also, you might consider looking into the
.B snmpconf
application (perl script) which can help you build an snmpd.conf file
by prompting you for information.  You should try it.  Really.  Go
ahead.  Right now.  Run:
.RS
.IP "snmpconf -g basic_setup"
.RE
.PP
to get you started. See the
.I snmpconf(1)
manual page for more information.
.SH EXTENSIBLE-MIB
.PP
The Net-SNMP SNMP agent reports much of its information through
queries to the EXTENSIBLEDOTMIB section of the MIB tree.  Every MIB in
this section has the following table entries in it.
.IP ".MIBINDEX -- index"
This is the table's index numbers for each of the DIRECTIVES listed below.
.IP ".ERRORNAME -- name"
The name of the given table entry.  This should be unique, but is not
required to be.
.IP ".ERRORFLAG -- errorFlag"
This is a flag returning either the integer value 1 or 0 if an error
is detected for this table entry.
.IP ".ERRORMSG -- errorMsg"
This is a DISPLAY-STRING describing any error triggering the errorFlag above.
.IP ".ERRORFIX -- errorFix"
If this entry is set to the integer value of 1 AND the errorFlag
defined above is indeed a 1, a program or script will get executed
with the table entry name from above as the argument.  The program to
be executed is configured in the net-snmp-config.h file at compile time.
.SS Directives
.IP "proc NAME"
.IP "proc NAME MAX"
.IP "proc NAME MAX MIN"
.IP
Checks to see if processes called NAME are running on the agent
machine.  An error flag (1) and a description message are then passed
to the EXTENSIBLEDOTMIB.PROCMIBNUM.1.ERRORFLAG and
EXTENSIBLEDOTMIB.PROCMIBNUM.1.ERRORMSG MIB columns (respectively) if
the NAME'd program is not found in the process table as reported by
PSCMD.
.IP
If MAX and MIN are not specified, MAX is assumed to be 
.B infinity
and MIN is assumed to be 1.
.IP
If MAX is specified but MIN is not specified, MIN is assumed to be 0.
.IP "procfix NAME PROG ARGS"
This registers a command that knows how to fix errors with the given
process NAME.  When EXTENSIBLEDOTMIB.PROCMIBNUM.1.ERRORFIX for a given
NAMEd program is set to the integer value of 1, this command will be
called.  It defaults to a compiled value set using the PROCFIXCMD
definition in the net-snmp-config.h file.
.IP "exec NAME PROG ARGS"
.IP "exec MIBNUM NAME PROG ARGS"
.IP
If MIBNUM is not specified, the agent executes the named PROG with
arguments of ARGS and returns the exit status and the first line of
the STDOUT output of the PROG program to queries of the
EXTENSIBLEDOTMIB.SHELLMIBNUM.1.ERRORFLAG and
EXTENSIBLEDOTMIB.SHELLMIBNUM.1.ERRORMSG mib columns (respectively).  All
STDOUT output beyond the first line is silently truncated.
.IP
If MIBNUM is specified, it acts as above but returns the exit status
to MIBNUM.ERRORFLAG.0 and the entire STDOUT output to the table
MIBNUM.ERRORMSG in a MIB table.  In this case, the MIBNUM.ERRORMSG mib
contains the entire STDOUT output, one MIB table entry per line of
output (ie, the first line is output as MIBNUM.ERRORMSG.1, the second
at MIBNUM.ERRORMSG.2, etc...).
.RS
.IP Note:
The PROG argument must be a full path to a real binary, as it is
executed under the exec() system call.  IE, you can not specify a path
to a shell script.  If you want to invoke a shell script, please
specify a path to the interpreter first as the PROG argument and then
a path to the shell script.  IE:  "exec myscript /bin/sh
/path/to/script arg1 ..."
.IP Note:
The MIBNUM must be specified in dotted-integer notation and can
not be specified as ".iso.org.dod.internet..." (should instead
be .1.3.6.1...).
.IP Note: 
The agent caches the exit status and STDOUT of the executed program
for 30 seconds after the initial query.  This is to increase speed and
maintain consistency of information for consecutive table queries.
The cache can be flushed by a snmp-set request of integer(1) to
EXTENSIBLEDOTMIB.VERSIONMIBNUM.VERCLEARCACHE.
.RE
.IP "extend NAME PROG ARGS"
.IP "extend MIBNUM NAME PROG ARGS"
.IP
This is similar to the 'exec' directive, but uses a different MIB output
structure (for both forms) which covers multi-line output as standard.
See NET-SNMP-EXTEND-MIB for details.
Output is cached for each entry separately, controlled by the
NET-SNMP-AGENT-MIB::nsCacheTable.
.IP "execfix NAME PROG ARGS"
This registers a command that knows how to fix errors with the given
exec or sh NAME.  When EXTENSIBLEDOTMIB.SHELLMIBNUM.1.ERRORFIX for a
given NAMEd entry is set to the integer value of 1, this command will
be called.  It defaults to a compiled value set using the EXECFIXCMD
definition in the net-snmp-config.h file.
.IP "disk PATH"
.IP "disk PATH [ MINSPACE | MINPERCENT% ]"
.IP
Checks the named disks mounted at PATH for available disk space.  If
the disk space is less than MINSPACE (kB) if specified or less than
MINPERCENT (%) if a % sign is specified, or DEFDISKMINIMUMSPACE (kB)
if not specified, the associated entry in the
EXTENSIBLEDOTMIB.DISKMIBNUM.1.ERRORFLAG MIB table will be set to (1) and
a descriptive error message will be returned to queries of
EXTENSIBLEDOTMIB.DISKMIBNUM.1.ERRORMSG.
.IP "includeAllDisks MINPERCENT%"
.IP
Adds  all  the  disks  that can be found on the system using the
setmntent(3) and getmntent(3), or fopen(3) and getmntent(3),  or
setfsent(3)  and  getfsent(3) system calls. If none of the above
system calls are available then it adds the root partition  "/",
(which  is  assumed to exist on any UNIX based system) using the
statfs(2) system call.
.IP
There can only be one 'includeAllDisks' directive in the config-
uration  file.  It  can  be  used in conjunction with the 'disk'
directive. They may be used in any order. The  'disk'  directive
overrides  the  disk  usage  specified  by the 'includeAllDisks'
directive, no matter in which order they are  specified  in  the
configuration file.
.IP
The 'includeAllDisks' directive only includes the disks that are
mounted when the snmpd daemon  is  started.  It  cannot  include
disks  that are dynamically loadable, such as with automount. So
the preferred way is to mount all the disks that will ever  need
to be monitored before starting the snmpd daemon.
.IP "load MAX1"
.IP "load MAX1 MAX5"
.IP "load MAX1 MAX5 MAX15"
.IP
Checks the load average of the machine and returns an error flag (1),
and an text-string error message
to queries of EXTENSIBLEDOTMIB.LOADAVEMIBNUM.1.ERRORFLAG and
EXTENSIBLEDOTMIB.LOADAVEMIBNUM.1.ERRORMSG (respectively) when the
1-minute, 5-minute, or 15-minute averages exceed the associated
maximum values.  If any of the MAX1, MAX5, or MAX15 values are
unspecified, they default to a value of DEFMAXLOADAVE.
.IP "file FILE [MAXSIZE]"
Monitors file sizes and makes sure they don't grow beyond a certain
size (in kilobytes).  MAXSIZE defaults to infinite if not specified,
and only monitors the size without reporting errors about it.
A maximum of 20 files can be monitored.
.IP "logmatch NAME PATH CYCLETIME REGEX"
Configures log file monitoring that can be queried via the
UCD-SNMP-MIB::logMatchTable.
.SS "Errors"
.PP
Any errors in obtaining the above information are reported via the
EXTENSIBLEDOTMIB.ERRORMIBNUM.1.ERRORFLAG flag and the
EXTENSIBLEDOTMIB.ERRORMIBNUM.1.ERRORMSG text-string description.
.SH AGENTX SUB-AGENTS
To enable AgentX support in the SNMP master agent, put the following
line in your snmpd.conf file:
.IP "master agentx"
See README.agentx for further details.
.IP "AgentXSocket addr"
This defines the address the master agent listens at.
The default is /var/agentx/master. By default the Unix Domain socket is
accessible only to subagents which have the same userid as the agent.
Another possibility is localhost:705
.IP "AgentXTimeout addr"
Defines the timeout period for an AgentX request.
Default is 1 second.
.IP "AgentXRetries addr"
Defines the number of retries for an AgentX request.
Default is 5 retries.
.IP "agentxperms socket_perms [directory_perms [username|userid [groupname|groupid]]]"
Defines the permissions of the AgentX socket. socket_perms and directory_perms must be octal digits (see 
.I chmod(1)
).
.P
You can also put the following in your subagent.conf file (where
"subagent" is the name you used in your init_snmp("subagent") api call:
.IP "agentXPingInterval NUM"
This makes the subagent try and reconnect every NUM seconds to the
master if it ever becomes (or starts) disconnected.
.SH SMUX SUB-AGENTS
To enable and SMUX based sub-agent, such as
.IR gated ,
use the
.I smuxpeer
configuration entry
.IP "smuxpeer OID PASS"
For 
.I gated
a sensible entry might be
.I smuxpeer .1.3.6.1.4.1.4.1.3 secret
.SH DYNAMICALLY LOADABLE MODULES
If the agent is built with support for the UCD-DLMOD-MIB it is capable
of loading agent MIB modules dynamically at startup through
the \fIdlmod\fR directive and during runtime through use of the UCD-DLMOD-MIB.
The following directive loads the shared object module file PATH which
uses the module name prefix NAME.
.IP "dlmod NAME PATH"
.IP
.SH ACCESS CONTROL
.B snmpd
supports the View-Based Access Control Model (VACM) as defined in RFC
2575.  To this end, it recognizes the following keywords in the
configuration file: \fIcom2sec\fR, \fIgroup\fR, \fIaccess\fR, and
\fIview\fR as well as some easier-to-use wrapper directives:
\fIrocommunity\fR, \fIrwcommunity\fR, \fIrouser\fR, \fIrwuser\fR.  If
IPv6 support has been enabled, the \fIrocommunity6\fR and
\fIrwcommunity6\fR tokens will also be available.  This section
defines how to configure the snmpd program to accept various types and
levels of access.
.IP "rouser USER [noauth|auth|priv [OID]]"
.IP "rwuser USER [noauth|auth|priv [OID]]"
Creates a SNMPv3 USM user in the VACM access configuration tables.  It
is more efficient (and powerful) to use the combined \fIgroup\fR,
\fIaccess\fR, and \fIview\fR directives instead, but these wrapper
directives are much simpler.
.IP
The minimum level of authentication and privacy the user must use is
specified by the first token (which defaults to "auth").  The OID
parameter restricts access for that user to everything below the given
OID.
.IP "rocommunity COMMUNITY [SOURCE [OID]]"
.IP "rwcommunity COMMUNITY [SOURCE [OID]]"
These create read-only and read-write communities that can be used to
access the agent.  They are a quick wrapper around the more complex
and powerful \fIcom2sec\fR, \fIgroup\fR, \fIaccess\fR, and \fIview\fR
directive lines.  They are not as efficient either, as groups aren't
created so the tables are possibly larger.  In other words: don't use
these if you have complex situations to set up.  If your setup is
simple or you don't mind a small performance hit, use these
directives.
.IP
The format of the SOURCE is token is described in the \fIcom2sec\fR
directive section below.  The OID token restricts access for that
community to everything below that given OID.
.IP "rocommunity6 COMMUNITY [SOURCE [OID]]"
.IP "rwcommunity6 COMMUNITY [SOURCE [OID]]"
They are the alternative directives to the \fIrocommunity\fR,
\fIrwcommunity\fR for the transport domain UDPIPv6. They are only
valid in specifing \fIUDPIPv6\fR as transport domain.
.IP
The format of the SOURCE is token is described in the \fIcom2sec6\fR
directive section below.  The OID token restricts access for that
community to everything below that given OID.
.IP "com2sec [-Cn CONTEXT] NAME SOURCE COMMUNITY"
This directive specifies the mapping from a source/community pair to
a security name. SOURCE can be a hostname, a subnet, or the word
\fI"default"\fR.
A subnet can be specified as IP/MASK or IP/BITS.
For example, given a directive
"com2sec myLocal 10.10.10.0/24 public"
then this would match requests from IP addresses 10.10.10.0 through
to 10.10.10.255, but not one from 10.10.11.1 or similar.
The first source/community combination that matches the incoming packet
is selected.  If a CONTEXT is specified, the community name gets
mapped to the SNMPv3 CONTEXT of the same name, otherwise the default context
("") is used.
.IP "com2sec6  [-Cn CONTEXT] NAME SOURCE COMMUNITY"
This directive is the IPv6 version of \fIcom2sec\fR.
A subnet can be specified as IPv6/IPv6MASK or IPv6/BITS.
It is only valid in specifing \fIUDPIPv6\fR as transport domain.
.IP "com2secunix [-Cn CONTEXT] NAME SOCKPATH COMMUNITY"
This directive is the Unix domain sockets version of \fIcom2sec\fR.
.IP "group NAME MODEL SECURITY"
This directive defines the mapping from securitymodel/securityname to group.
MODEL is one of \fIv1\fR, \fIv2c\fR, or \fIusm\fR.
.IP "access NAME CONTEXT MODEL LEVEL PREFX READ WRITE NOTIFY"
The access directive maps from group/security model/security level to
a view. 
MODEL is one of \fIany\fR, \fIv1\fR, \fIv2c\fR, or \fIusm\fR.
LEVEL is one of \fInoauth\fR, \fIauth\fR, or \fIpriv\fR.
PREFX specifies how CONTEXT should be matched against the context of
the incoming pdu, either \fIexact\fR or \fIprefix\fR.
READ, WRITE and NOTIFY specifies the view to be used for the corresponding 
access.
For v1 or v2c access, LEVEL will be noauth, and CONTEXT will be empty.
.IP "view VNAME TYPE OID [MASK]"
defines a named "view" - a subset of the overall OID tree.  This is most
commonly a single subtree, but several \fIview\fR directives can be given
with the same view name (VNAME), to build up a more complex collection of OIDs.
TYPE is either \fIincluded\fR or \fIexcluded\fR, which can again define
a more complex view (e.g. by excluding certain sensitive objects
from an otherwise accessible subtree).
.IP
MASK is a list of hex octets (optionally separated by '.' or ':') with
the set bits indicating which subidentifiers in the view OID to match
against.  If not specified, this defaults to matching the OID exactly
(all bits set), thus defining a simple OID subtree.  So:
.RS
.RS
view iso1 included .iso  0xf0
.br
view iso2 included .iso
.br
view iso3 included .iso.org.dod.mgmt  0xf0
.RE
.RE
.IP
would all define the same view, covering the whole of the 'iso(1)' subtree
(with the third example ignoring the subidentifiers not covered by the mask).
.IP
More usefully, the mask can be used to define a view covering a particular
row (or rows) in a table, by matching against the appropriate table index
value, but skipping the column subidentifier:
.RS
.RS
.IP "view ifRow4 included .1.3.6.1.2.1.2.2.1.0.4  0xff:a0"
.RE
.RE
.IP
Note that a mask longer than 8 bits must use ':' to separate the individual
octets.
.IP "VACM Examples:"
.nf
#        sec.name  source          community
com2sec  local     localhost       private
com2sec  mynet     10.10.10.0/24   public
com2sec  public    default         public
com2sec6 mynet     fec0::/64       public

#             sec.model  sec.name
group mygroup v1         mynet
group mygroup v2c        mynet
group mygroup usm        mynet
group local   v1         local
group local   v2c        local
group local   usm        local
group public  v1         public
group public  v2c        public
group public  usm        public

#           incl/excl subtree                          mask
view all    included  .1                               80
view system included  system                           fe
view mib2   included  .iso.org.dod.internet.mgmt.mib-2 fc

#              context sec.model sec.level prefix read   write notify
access mygroup ""      any       noauth    exact  mib2   none  none
access public  ""      any       noauth    exact  system none  none
access local   ""      any       noauth    exact  all    all   all
.IP "Default VACM model"
The default configuration of the agent, as shipped, is functionally
equivalent to the following entries:
.nf
com2sec	public	default	public
group	public	v1	public
group	public	v2c	public
group	public	usm	public
view 	all	included	.1
access	public	""	any	noauth	exact	all	none	none
.fi
.RE
.SH SNMPv3 CONFIGURATION
.PP
.IP "engineID STRING"
The snmpd agent needs to be configured with a unique engineID to be able to
respond to SNMPv3 messages.  With this configuration file line, the
engineID will be configured from STRING. 
.IP "engineIDType 1|2|3"
Defines that the engineID should be built from the IPv4 address (1), IPv6 address (2) or MAC address (3). Beware that you might run into trouble on IP 
address changes!
.IP "engineIDNic interface"
Defines the interface (e.g. "eth1") that should be used to determine the MAC address in case of "engineIDType 3". Default is eth0.
.P
If neither an engineID, engineIDType or engineIDNic directive is present, 
the value of the engineID is built from 2 fairly random elements:
a random number and the current time in seconds. This is the recommended
approach.
.IP "createUser [-e ENGINEID] username (MD5|SHA) authpassphrase [DES|AES] [privpassphrase]"
.IP
MD5 and SHA are the authentication types to use.  DES and AES are the
privacy protocols to use.  If the privacy
passphrase is not specified, it is assumed to be the same as the
authentication passphrase.  Note that the users created will be
useless unless they are also added to the VACM access control tables
described above.
.IP
SHA authentication and DES/AES privacy require OpenSSL to be installed and
the agent to be built with OpenSSL support.  MD5 authentication may be
used without OpenSSL.
.IP
Warning: the minimum pass phrase length is 8 characters.
.IP
SNMPv3 users can be created at runtime using the
.I snmpusm(1)
command.
.IP
Instead of figuring out how to use this directive and where to put it
(see below), just run "net-snmp-config --create-snmpv3-user" instead,
which will add one of these lines to the right place.
.IP
This directive should be placed into the
PERSISTENT_DIRECTORY/snmpd.conf file instead of the other normal
locations.  The reason is that the information is read from the file
and then the line is removed (eliminating the storage of the master
password for that user) and replaced with the key that is derived from
it.  This key is a localized key, so that if it is stolen it can not
be used to access other agents.  If the password is stolen, however,
it can be.
.IP
If you need to localize the user to a particular EngineID (this is
useful mostly in the similar snmptrapd.conf file), you can use the -e
argument to specify an EngineID as a hex value (EG, "0x01020304").
.IP
If you want to generate either your master or localized keys directly,
replace the given password with a hexstring (preceeded by a "0x") and
precede the hex string by a -m or -l token (respectively).  EGs:
.IP
.RS
.nf
[these keys are *not* secure but are easy to visually parse for
counting purposes.  Please generate random keys instead of using
these examples]

createUser myuser SHA -l 0x0001020304050607080900010203040506070809 AES -l 0x00010203040506070809000102030405
createUser myuser SHA -m 0x0001020304050607080900010203040506070809 AES -m 0x0001020304050607080900010203040506070809
.fi
.RE
.IP
Due to the way localization happens, localized privacy keys are
expected to be the length needed by the algorithm (128 bits for all
supported algorithms).  Master encryption keys, though, need to be the
length required by the authentication algorithm not the length
required by the encrypting algorithm (MD5: 16 bytes, SHA: 20 bytes).
.IP
.SH SETTING SYSTEM INFORMATION
.IP "syslocation STRING"
.IP "syscontact STRING"
.IP "sysname STRING"
Sets the system location, system contact or system name for the agent.
This information is reported in the 'system' group the mibII tree.
Ordinarily these objects (sysLocation.0, sysContact.0 and sysName.0)
are read-write.  However, specifying the value for one of these
objects by giving the appropriate token makes the corresponding object
read-only, and attempts to set the value of the object will result in
a notWritable error response.
.IP "sysservices NUMBER"
Sets the value of the system.sysServices.0 object.
For a host, a good value is 72.
.IP "sysdescr STRING"
.IP "sysobjectid OID"
Sets the system description or object ID for the agent.
Although these values are not SNMP-writable, it is conceivable
that a network administrator may wish to configure them to something
other than the default values.
.IP "leave_pidfile yes"
Instructs the agent to not remove its pid file on shutdown. Equivalent to
specifying "-U" on the command line.
.IP "agentaddress [<transport-specifier>:]<transport-address>[,...]"
Makes the agent list on the specified comma-separated list of
listening addresses instead of the default behaviour, which is to
listen on UDP port 161 on all IPv4 interfaces.  See the section 
.B LISTENING ADDRESSES
in the
.I snmpd(8)
manual page for more information about the format of listening
addresses.  For example, specifying
.I "agentaddress 161,tcp:161,localhost:9161"
will make the agent listen on UDP port 161 on all IPv4 interfaces, TCP
port 161 on all IPv4 interfaces and UDP port 9161 only on the interface
associated with the localhost address.
.IP "agentgroup groupid"
Change to this gid after opening port. The groupid may refer to a group
by name or a number if the group number starts with '#'. For example,
specifying
.I agentgroup snmp
will cause the agent to run as the snmp group or
.I agentgroup #10
will cause the agent to run as the group with groupid 10.
.IP "agentuser uid"
Change to this uid after opening port. The userid may refer to a user
by name or a number if the user number starts with '#'. For example,
specifying
.I agentuser snmp
will cause the agent to run as the snmp user or
.I agentuser #10
will cause the agent to run as the user with userid 10.
.IP "interface NAME TYPE SPEED"
For interfaces where the agent fails to guess correctly on the type and
speed, this directive can supply additional information.
TYPE is a type value as given in the IANAifType-MIB.
.IP "ignoredisk STRING"
When scanning for available disk devices the agent might block in trying
to open all possible disk devices. This might lead to a timeout when
walking the device tree. Sometimes the next walk will run without timeout,
sometimes it will timeout every time you try it.
.IP
If you experience such behaviour you might add this directive and give all
device names not to be checked (i.e. opened). You might have more than one
such directive in your configuration file stating all devices not to be
opened. You might also specify those devices using wildcards similar to
the syntax you can use in a bourne shell (see examples below).
.IP
.B Note:
For a list of devices scanned for every system please consult the sources
(host/hr_disk.c) and check for the Add_HR_Disk_entry() calls relevant for
your type of OS.
.IP
Examples:
.IP
ignoredisk /dev/rdsk/c0t2d0
.IP
This directive prevents the device /dev/rdsk/c0t2d0 from being scanned.
.IP
ignoredisk /dev/rdsk/c0t[!6]d0
.IP
This directive prevents all devices /dev/rdsk/c0tXd0 except .../c0t6d0
from being scanned. For most systems similar is the following directive:
.IP
ignoredisk /dev/rdsk/c0t[0-57-9a-f]d0
.IP
ignoredisk /dev/rdsk/c1*
.IP
This directive prevents all devices whose device names start with /dev/rdsk/c1
from being scanned.
.IP
ignoredisk /dev/rdsk/c?t0d0
.IP
This directive prevents all devices /dev/rdsk/cXt0d0 ('X' might be any char)
from being scanned.
.IP
You might use more than one such wildcard expression in any such directive.
.IP "storageUseNFS NUMBER"
Setting storageUseNFS to 1 causes all NFS and NFS-like file systems to be
marked as 'Network Disks' in the hrStorageTable. This is according to RFC 2790.
Not setting storageUseNFS or setting it to 2 causes NFS and NFS-like file
systems to be marked as 'Fixed Disks' as it has been in previous versions of
the ucd-snmp SNMP agent.
.IP "authtrapenable NUMBER"
Setting authtrapenable to 1 enables generation of authentication failure
traps.  The default value is disabled(2).  Ordinarily the corresponding
object (snmpEnableAuthenTraps.0) is read-write, but setting its value
via this token makes the object read-only, and attempts to set the
value of the object will result in a notWritable error response.
.IP "override [-rw] OID TYPE VALUE"
This directive allows you to override a particular OID with a
different value (and possibly a different type of value).  The -rw
flag will allow snmp SETs to modify it's value as well. (note that if
you're overriding original functionality, that functionality will be
entirely lost.  Thus SETS will do nothing more than modify the
internal overridden value and will not perform any of the original
functionality intended to be provided by the MIB object.  It's an
emulation only.)  An example:
.IP
override sysDescr.0 octet_str "my own sysDescr"
.IP
That line will set the sysDescr.0 value to "my own sysDescr" as well
as make it modifiable with SNMP SETs as well (which is actually
illegal according to the MIB specifications).
.IP
Note that care must be taken when using this.  For example, if you try
to override a property of the 3rd interface in the ifTable with a new
value and later the numbering within the ifTable changes it's index
ordering you'll end up with problems and your modified value won't
appear in the right place in the table.
.IP
Valid TYPEs are: integer, uinteger, octet_str, object_id, counter,
null (for gauge's, use "uinteger"; for bit strings, use "octet_str").
Note that setting an object to "null" effectively delete's it as being
accessible.  No VALUE needs to be given if the object type is null.
.IP
More types should be available in the future.
.IP "maxGetbulkRepeats NUM"
Sets the maximum number of responses allowed for a single variable in
a getbulk request.  Set to 0 to enable the default and set it to -1 to
enable unlimited.  Because memory is allocated ahead of time, sitting
this to unlimited is not considered safe if your user population can
not be trusted.  A repeat number greater than this will be truncated
to this value.
.IP
This is set by default to -1.
.IP "maxGetbulkResponses NUM"
Sets the maximum number of responses allowed for a getbulk request.
This is set by default to 100.  Set to 0 to enable the default and set
it to -1 to enable unlimited.  Because memory is allocated ahead of
time, sitting this to unlimited is not considered safe if your user
population can not be trusted.
.IP
In general, the total number of responses will not be allowed to
exceed the maxGetbulkResponses number and the total number returned
will be an integer multiple of the number of variables requested times
the calculated number of repeats allow to fit below this number.
.IP
Also not that processing of maxGetbulkRepeats is handled first.
.SH "SETTING UP TRAP AND/OR INFORM DESTINATIONS"
.IP "trapcommunity STRING"
This defines the default community string to be used when sending traps.
Note that this command must be used prior to any of the following three
commands that are intended use this community string.
.IP "trapsink HOST [COMMUNITY [PORT]]"
.IP "trap2sink HOST [COMMUNITY [PORT]]"
.IP "informsink HOST [COMMUNITY [PORT]]"
These commands define
the hosts to receive traps (and/or inform notifications). The
daemon sends a Cold Start trap when it starts up. If enabled, it also sends
traps on authentication failures.  Multiple \fItrapsink\fR, \fItrap2sink\fR
and \fIinformsink\fR lines may be specified to specify multiple destinations.
Use \fItrap2sink\fR to send SNMPv2 traps and \fIinformsink\fR to send
inform notifications.
If COMMUNITY is not specified, the string from a preceding \fItrapcommunity\fR
directive will be used. If PORT is not specified, the well known SNMP trap
port (162) will be used.
.IP "trapsess [SNMPCMD_ARGS] HOST"
This is a more generic trap configuration token that allows any type
of trap destination to be specified with any version of SNMP.  See the 
.I snmpcmd(1)
manual page for further details on the arguments that can be passed as
.I "SNMPCMD ARGS".
In addition to the arguments listed there, the special argument
\fI-Ci\fR specifies that you want inform notifications to be used
instead of unacknowledged traps (this requires that you also specify a 
version number of v2c or v3 as well).
.SH "PROXY SUPPORT"
.IP "proxy [-Cn CONTEXTNAME] [SNMPCMD ARGS] HOST OID [REMOTEOID]"
.IP
This token specifies that any incoming requests under OID should be
proxied on to another HOST instead.  Use OID .1.3 (not just .1) to proxy 
the entire MIB tree. If a CONTEXTNAME is specified, it
assigns the proxied tree to a particular context name within the local
agent.  This is the proper way to query multiple agents through a
single proxy.  Assign each remote agent to a different context name.
Then you can use "snmpwalk -n contextname1" to walk one remote proxied
agent and "snmpwalk -n contextname2" to walk another, assuming you are
using SNMPv3 to talk to the proxy (snmpv1 and snmpv2c context mappings
aren't currently supported but might be in the future).  Optionally,
relocate the local OID tree to the new location at the REMOTEOID.  To
authenticate to HOST you should use the appropriate set of
.I "SNMPCMD ARGS."
See the
.I snmpcmd(1)
manual page for details.
.IP
Examples:
.RS
.nf
# assigns the entire mib tree on remotehost1 to the context of the
# same name:
proxy -Cn remotehost1 -v 1 -c public remotehost1 .1.3
# ditto, but for remotehost 2
proxy -Cn remotehost2 -v 1 -c public remotehost2 .1.3
# proxies only the ucdavis enterprises tree to the remote host using snmpv1
proxy -v 1 -c public remotehost .1.3.6.1.4.1.2021
# uses v3 to access remotehost and converts the remote .1.3.6.1.2.1.1
# oid to local .1.3.6.1.3.10 oid (another way to access mulitple hosts
# without using contexts)
proxy -v 3 -l noAuthNoPriv -u user remotehost .1.3.6.1.3.10 .1.3.6.1.2.1.1
.fi
.RE
.SH "PASS-THROUGH CONTROL"
.IP "pass MIBOID EXEC"
(If you're writing perl scripts, please see the embedded perl support
information later in this manual page).  Passes entire control of
MIBOID to the EXEC program.  The EXEC program is called in one of the
following three ways:
.RS
.IP "EXEC -g MIBOID"
.IP "EXEC -n MIBOID"
.IP
These call lines match to SNMP get and getnext requests.  It is
expected that the EXEC program will take the arguments passed to it
and return the appropriate response through it's stdout.  
.IP
The first line of stdout should be the MIB OID of the returning value.
The second line should be the TYPE of value returned, where TYPE is
one of the text strings:
.B string, integer, unsigned, objectid, timeticks, ipaddress, counter, 
or
.B gauge.
The third line of stdout should be the VALUE corresponding with the
returned TYPE.
.IP
For instance, if a script was to return the value integer value "42"
when a request for .1.3.6.1.4.100 was requested, the script should
return the following 3 lines:
.br
.RS
  .1.3.6.1.4.100
.br
  integer
.br
  42
.RE
.IP
To indicate that the script is unable to comply with the request due
to an end-of-mib condition or an invalid request, simple exit and
return no output to stdout at all.  An SNMP error will be generated
corresponding to the SNMP noSuchName response.
.IP "EXEC -s MIBOID TYPE VALUE"
.IP 
For SNMP set requests, the above call method is used.  The TYPE passed
to the EXEC program is one of the text strings:
.B integer, counter, gauge, timeticks, ipaddress, objid,
or 
.B string,
indicating the type of value passed in the next argument.
.IP
Return nothing to stdout, and the set will assumed to have been
successful.  Otherwise, return one of the following error strings to
signal an error:
.B not-writable, 
or 
.B wrong-type
and the appropriate error response will be generated instead.
.RS
.IP Note:
By default, the only community allowed to write (ie snmpset) to your
script will be the "private" community,or community #2 if defined
differently by the "community" token discussed above.  Which
communities are allowed write access are controlled by the RWRITE
definition in the snmplib/snmp_impl.h source file.
.RE
.RE
.IP
Example (in snmpd.conf):
.IP
pass .1.3.6.1.4.1.2021.255 /path/to/local/passtest
.RE
.IP "pass_persist MIBOID EXEC"
Passes entire control of MIBOID to the EXEC program.  
Similar to pass, but the EXEC program continues to run after the initial
request is answered.  Also, pass and pass_persist block till they return.
.IP
Upon initialization, EXEC is passed the string "PING\\n" in stdin,
and it should respond by printing "PONG\\n" to stdout.
.IP
For get and getnext requests, EXEC program is passed two lines,
the command (get or getnext) and the MIB OID.  It should return
three lines, the MIB OID, the TYPE of value returned,
the VALUE corresponding with the returned TYPE.
.IP
For example, if the value for .1.3.6.1.4.100 was requested, the following
2 lines would be passed in to stdin:
.br
.RS
  get
.br
  .1.3.6.1.4.100  
.RE
.IP
To return the value, say, 42, the script would write to stdout:
.br
.RS
  .1.3.6.1.4.100
.br
  integer
.br
  42
.RE
.IP
To indicate that the script is unable to comply with the request due
to an end-of-mib condition or an invalid request, print "NONE\\n" to
stdout.
.IP
Example (in snmpd.conf):
.IP
pass_persist .1.3.6.1.4.1.2021.255 /path/to/local/pass_persisttest
.RE
.SH "EMBEDDED PERL SUPPORT"
.PP
Warning: though embedded perl is working, not much functionality has
been implemented yet and thus writing mib module pieces for the agent
within perl is not trivial at this point.  It should get better in
future releases.
.PP
The net-snmp package has ability to call perl scripts directly inside
the agent through embedded perl technology (similar to mod_perl for
the apache web server).  This must be turned on at compile time by
passing --enable-embedded-perl to the configure script when the
package is built.  To see if your package was built with embedded
perl, run "net-snmp-config --configure-options" and see if that flag
was used.
.PP
If compiled in, it defines the following snmpd.conf configuration
directives:
.IP "disablePerl true"
This will turn off perl support entirely.  If the embedded perl
support stops working due to a change in perl, etc, this will stop any
calls to the perl core.

.IP "perlInitFile FILE"
Use FILE as the initialization file.  This file is normally
DATADIR/snmp/snmp_perl.pl but this token can override that default.
This file performs any in-perl initialization that is needed before
the rest of the perl directives (below) are called.  It is sourced
once just before the first perl directive is parsed.  See the default
file for an example of the initialization it performs.
.IP "perl EXPRESSION"
Calls perl to evaluate an expression.  Normally you'd want to do
something like register a function to call when an OID is requested,
but you can really do anything perl related you want.  For example:
.IP
perl print "hello world\\n";
.IP
is the most basic hello world example.
.IP
The init script by default initializes a $agent variable which
is a pointer to a NetSnmp::agent object through which you can register
callbacks when a section of the OID tree is hit:
.nf
perl use Data::Dumper;
perl sub myroutine  { print "got called: ",Dumper(@_),"\\n"; }
perl $agent->register('mylink', '.1.3.6.1.8765', \\&myroutine);
.fi
.IP
Sourcing an external file:
.RS
.nf
perl 'do /path/to/file.pl';
.fi
.RE
.IP
No better examples exist at the moment, unfortunately.  Look for
improved support in future releases.  Comments on how this looks as an
architecture are certainly appreciated now.
.SH "DISMAN-EVENT-MIB SUPPORT (READ: SENDING TRAPS ON ERRORS)"
.PP
Warning: this implementation has not been extensively tested and is
additionally not known to be entirely complete.  The concepts defined
here should function appropriately, however, but no promises are made
at this time.
.PP
If your agent was compiled with support for the DISMAN-EVENT-MIB (you
can enable this by running the net-snmp configure script with the
--with-mib-modules=disman/event-mib argument) you have support for
having the agent check its own data at regular intervals and to send
out traps when certain conditions occur.  Traps are sent when
expressions are first noticed, not once per evaluation.  Once a test
expression fires a trap, the test will have to fail again before a new
trap is sent.  See the DISMAN-EVENT-MIB documentation for more
details. This can be configured either using the MIB tables themselves
or by using these special key words:
.IP "agentSecName NAME"
The DISMAN-EVENT-MIB support requires a valid SNMPv3 user name with
which to scan your agent (even if you normally use SNMPv1 or SNMPv2c
for querying the agent).  This user can either be specified using the
agentSecName token or by explicitly listing one on the "monitor" lines
described below using the -u switch.  Either way, a "rouser" line (or
equivalent access control settings) must also be specified with the
same security name name.  If you need an example, just do something
like this:
.RS
.IP
.nf
agentSecName internal
rouser internal
.fi
.RE
.IP
And everything below should work just fine.
.IP "monitor [OPTIONS] NAME EXPRESSION"
This token tells the agent to monitor itself for problems based on
EXPRESSION.  Expression is a simple expression based on an oid, a
comparison operator (!=, ==, <, <=, >, >=) and an integer value (see
the examples below).  NAME is merely an arbitrary name of your
choosing for administrative purposes only.  OPTIONS include the
following possibilities:
.RS
.IP "-t"
Use a threshold monitor instead of a boolean monitor.  This means that
expression should be a low and high value.  If the given OID passes
beyond the high value, a rising alarm will triggered.  A falling alarm
will then be triggered after it falls below the low value.
.IP "-r FREQUENCY"
Monitors the given expression every FREQUENCY seconds.  The default is
600 (10 minutes). 
.IP "-u SECNAME"
Use the SECNAME security name for scanning the local host.
Specifically, this SECNAME must then be given access control rights
via something like the "rouser" snmpd.conf token for this expression
to be valid at all.  If not specified, it uses the default security
name specified by the agentsecname snmpd.conf token.  Either the -u
flag or a valid agentsecname token must be specified (and that name
must be given proper access control rights via a "rouser" token).
.IP "-o OID"
Specifies additional object values to be delivered with in the
resulting trap in addition to the normal trap objects.  This is useful
for obtaining other columns in the table for the row that triggered
the expression.  See the examples below for more details.
.IP "-e EVENTNAME"
Specifies an event name that describes what to do when the trigger is
fired.  Currently, this must be the name of a notificationEvent event
as described below.
.RE
.IP
The following example configuration checks the hrSWRunPerfTable table
(listing running processes) for any process which is consuming > 10Mb
of memory.  It performs this check every 600 seconds (the default).
For every process it finds exceeding the limit, it will end out
exactly one notification.  In addition to the normal hrSWRunPerfMem
oid and value sent in the trap, the hrSWRunName object will also be
sent.  Note that the hrSWRunName object actually occurs in a different
table, but since the indexes to the two tables are the same this works
out alright.
.RS
.IP
.nf
rouser me
monitor -u me -o sysUpTime.0 -o hrSWRunName "high process memory" hrSWRunPerfMem > 10000
.fi
.fi
.RE
.IP
The above line would produce a trap which, when formated by snmptrapd, would
look like:
.RS
.IP
.nf
2002-04-05 13:33:53 localhost.localdomain [udp:127.0.0.1:32931]:
        sysUpTimeInstance = Timeticks: (1629) 0:00:16.29        snmpTrapOID.0 = OID: mteTriggerFired    mteHotTrigger = high process memory     mteHotTargetName =      mteHotContextName =     mteHotOID = OID: hrSWRunPerfMem.1968    mteHotValue = 28564     hrSWRunName.1968 = "xemacs"
.fi
.RE
.IP
This shows my xemacs process using 28Mb of resident memory.  Which,
considering it's xemacs, is not that surprising.
.IP
Threshold example:
.RS
.nf
.IP
monitor -t -r 15 -o prNames -o prErrMessage "process table" prErrorFlag 0 1
.fi
.RE
.IP "notificationEvent NAME NOTIFICATION [[-w] OID_OBJECT ...]"
This will create a notification event, which can be fired by attaching
it to a monitor using a monitor's -e switch and an identical NAME
field.  The NOTIFICATION to be sent should be the OID of a
notification.  Additional objects can be included, and by default the
suffix of the row/object being monitored will be appended to the
object identifier unless it's told not to be a wild-card object by
prefixing it with the -w switch.  EG, if you're monitoring the ifTable
and you want your trap to include the ifDescr object for the row that
was discovered, don't add the -w switch and the .INDEX field will be
appended.  If the OID is fully qualified (EG, "sysContact.0") and no
instance suffix should be appended to it then add a -w switch before
it.  See the linkUpDownNotifications token below for example usage of
this token to send the linkUp and linkDown traps.
.IP "linkUpDownNotifications yes"
This will make the DISMAN-EVENT-MIB support watch the ifTable to
determine when a network interface is taken up or down.  When this
happens, a linkUp or linkDown notification will be triggered.  This is
exactly equivalent to doing:
.RS
.IP
.nf
notificationEvent  linkUpTrap    linkUp   ifIndex ifAdminStatus ifOperStatus
notificationEvent  linkDownTrap  linkDown ifIndex ifAdminStatus ifOperStatus

monitor  -r 60 -e linkUpTrap   "Generate linkUp" ifOperStatus != 2
monitor  -r 60 -e linkDownTrap "Generate linkDown" ifOperStatus == 2
.fi
.RE
.IP "defaultMonitors yes"
By default, the agent and the DISMAN-EVENT-MIB support do nothing
until configured.  Typically people wish to watch a bunch of tables
within the UCD-SNMP-MIB which are designed specifically for reporting
problems.  If the "defaultMonitors yes" line is put into the
snmpd.conf file (which must be accompanied by an appropriate
agentSecName line and a rouser line), the following monitoring
conditions will be installed:
.RS
.IP
.nf
monitor	-o prNames -o prErrMessage "process table" prErrorFlag != 0
monitor	-o memErrorName -o memSwapErrorMsg "memory" memSwapError != 0
monitor	-o extNames -o extOutput "extTable" extResult != 0
monitor	-o dskPath -o dskErrorMsg "dskTable" dskErrorFlag != 0
monitor	-o laNames -o laErrMessage  "laTable" laErrorFlag != 0
monitor	-o fileName -o fileErrorMsg  "fileTable" fileErrorFlag != 0
.fi
.RE
.SH "DEBUGGING AND OTHER EXTENSIBILITY NOTES"
If you're trying to figure out aspects of the various mib modules
(possibly some that you've added yourself), the following may help you
spit out some useful debugging information.  First off, please read
the snmpd manual page on the -D flag.  Then the following
configuration snmpd.conf token, combined with the -D flag, can produce
useful output:
.IP "injectHandler HANDLER modulename"
This will insert new handlers into the section of the mib tree
referenced by "modulename".  The types of handlers available for
insertion are:
.RS
.nf
stash_cache  - Caches information returned from the lower level.  This
               greatly help the performance of the agent, at the cost
               of caching the data such that its no longer "live" for
               30 seconds (in this future, this will be configurable).
               Note that this means snmpd will use more memory as well
               while the information is cached.  Currently this only
               works for handlers registered using the table_iterator
               support, which is only a few mib tables.  To use it,
               you need to make sure to install it before the
               table_iterator point in the chain, so to do this:

                  injectHandler stash_cache NAME table_iterator

               If you want a table to play with, try walking the
               nsModuleTable with and without this injected.

debug        - Prints out lots of debugging information when
               the -Dhelper:debug flag is passed to the snmpd
               application.

read_only    - Forces turning off write support for the given module.

serialize    - If a module is failing to handle multiple requests
               properly (using the new 5.0 module API), this will force
               the module to only receive one request at a time.

bulk_to_next - If a module registers to handle getbulk support, but
               for some reason is failing to implement it properly,
               this module will convert all getbulk requests to
               getnext requests before the final module receives it.
.fi
.RE
.IP "Figuring out module names"
To figure out which modules you can inject things into, snmpwalk the
nsModuleTable which will give you a list of all named modules
registered within the agent.
.SH "EXAMPLE CONFIGURATION FILE"
See the EXAMPLE.CONF file in the top level source directory for a more
detailed example of how the above information is used in real
examples.
.SH "RE-READING snmpd.conf AND snmpd.local.conf"
The Net-SNMP agent can be forced to re-read its configuration files.
It can be told to do so by one of two ways:
.IP 1.
An snmpset of integer(1) to UCD-SNMP-MIB::versionUpdateConfig.0
(.1.3.6.1.4.1.2021.100.11.0)
.IP 2.
A "kill -HUP" signal sent to the snmpd agent process.
.SH "FILES"
SYSCONFDIR/snmp/snmpd.conf
.SH "SEE ALSO"
snmpconf(1), snmpusm(1), snmp.conf(5), snmp_config(5), snmpd(8), EXAMPLE.conf, read_config(3).
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