snmpcmd (1) - Linux Manuals

snmpcmd: options and behaviour common to most of the Net-SNMP command-line tools

NAME

snmpcmd - options and behaviour common to most of the Net-SNMP command-line tools

SYNOPSIS

snmpcmd [OPTIONS] AGENT [PARAMETERS]

DESCRIPTION

This manual page describes the common options for the SNMP commands: snmpbulkget, snmpbulkwalk, snmpdelta, snmpget, snmpgetnext, snmpnetstat, snmpset, snmpstatus, snmptable, snmptest, snmptrap, snmpdf, snmpusm , snmpwalk . The command line applications use the SNMP protocol to communicate with an SNMP capable network entity, an agent. Individual applications typically (but not necessarily) take additional parameters that are given after the agent specification. These parameters are documented in the manual pages for each application.

COMMAND-LINE CONFIG OPTIONS

In addition to the options described in this manual page, all of the tokens described in the snmp.conf and other .conf manual pages can be used on the command line of Net-SNMP applications as well by prefixing them with "--". EG, specifying --dontLoadHostConfig=true on the command line will turn of loading of the host specific configuration files.

The snmp.conf file settings and the double-dash arguments over-ride the single-dash arguments. So it's important to note that if single-dash arguments aren't working because you have settings in the snmp.conf file that conflict with them then you'll need to use the longer-form double-dash arguments to successfully trump the snmp.conf file settings.

Generic Options

Thes options control how the Net-SNMP commands behave regardless of what version of SNMP you are using. See further below for options that control specific versions or sub-modules of the SNMP protocol.

-d

Dump (in hexadecimal) the raw SNMP packets sent and received.

-D[TOKEN[,...]]

Turn on debugging output for the given TOKEN(s). Try ALL for extremely verbose output.

-h, --help

Display a brief usage message and then exit.

-H

Display a list of configuration file directives understood by the command and then exit.

-I [brRhu]

Specifies input parsing options. See INPUT OPTIONS below.

-L [eEfFoOsS]

Specifies output logging options. See LOGGING OPTIONS below.

-m MIBLIST

Specifies a colon separated list of MIB modules (not files) to load for this application. This overrides (or augments) the environment variable MIBS, the snmp.conf directive mibs, and the list of MIBs hardcoded into the Net-SNMP library.

If MIBLIST has a leading '-' or '+' character, then the MIB modules listed are loaded in addition to the default list, coming before or after this list respectively. Otherwise, the specified MIBs are loaded instead of this default list.

The special keyword ALL is used to load all MIB modules in the MIB directory search list. Every file whose name does not begin with "." will be parsed as if it were a MIB file.

-M DIRLIST

Specifies a colon separated list of directories to search for MIBs. This overrides (or augments) the environment variable MIBDIRS, the snmp.conf directive mibdirs, and the default directory hardcoded into the Net-SNMP library (/usr/share/snmp/mibs).

If DIRLIST has a leading '-' or '+' character, then the given directories are added to the default list, being searched before or after the directories on this list respectively. Otherwise, the specified directories are searched instead of this default list.

Note that the directories appearing later in the list have have precedence over earlier ones. To avoid searching any MIB directories, set the MIBDIRS environment variable to the empty string ("").

Note that MIBs specified using the -m option or the mibs configuration directive will be loaded from one of the directories listed by the -M option (or equivalents). The mibfile directive takes a full path to the specified MIB file, so this does not need to be in the MIB directory search list.

-v 1 | 2c | 3

Specifies the protocol version to use: 1 (RFCs 1155-1157), 2c (RFCs 1901-1908), or 3 (RFCs 2571-2574). The default is typically version 3. Overrides the defVersion token in the snmp.conf file. -O [abeEfnqQsStTuUvxX] Specifies output printing options. See OUTPUT OPTIONS below.

-P [cdeRuwW]

Specifies MIB parsing options. See MIB PARSING OPTIONS below.

-r retries

Specifies the number of retries to be used in the requests. The default is 5.

-t timeout

Specifies the timeout in seconds between retries. The default is 1. Floating point numbers can be used to specify fractions of seconds.

-V, --version

Display version information for the application and then exit.

-Yname=value

--name=value

Allows one to specify any token ("name") supported in the snmp.conf file and sets its value to "value". Overrides the corresponding token in the snmp.conf file. See snmp.conf(5) for the full list of tokens.

SNMPv3 Options

The following options are generic to all forms of SNMPv3, regardless of whether it's the original SNMPv3 with USM or the newer SNMPv3 over (D)TLS support.

-l secLevel

Set the securityLevel used for SNMPv3 messages (noAuthNoPriv|authNoPriv|authPriv). Appropriate pass phrase(s) must provided when using any level higher than noAuthNoPriv. Overrides the defSecurityLevel token in the snmp.conf file.

-n contextName

Set the contextName used for SNMPv3 messages. The default contextName is the empty string "". Overrides the defContext token in the snmp.conf file.

SNMPv3 over TLS Options

These options pass transport-specific parameters to the TLS layer. If you're using SNMP over TLS or DTLS you'll need to pass a combination of these either through these command line options or through snmp.conf configuration tokens.

A note about <certificate-specifier>s: Net-SNMP looks for X.509 certificates in each of the normal SNMP configuration directory search paths under a "tls" subdirectory. IE, it will look in ~/.snmp/tls and in /usr/local/share/snmp/tls for certificates. The certificate components (eg, the public and private halves) are stored in sub-directories underneath this root set of directories. See the net-snmp-cert tool for help in importing, creating and managing Net-SNMP certificates. <certificate-specifier>s can reference either a fingerprint of the certificate to use (the net-snmp-cert tool can help you figure out the certificates) or the filename's prefix can be used. For example, if you had a "snmpd.crt" certificate file then you could simply refer to the certificate via the "snmpd" specifier.

-T localCert=<certificate-specifier>

Indicates to the transport which key should be used to initiate (D)TLS client connections. This would typically be a certificate found using the certificate fingerprint, the application name (eg snmpd, snmptrapd, perl, python) or genericized name "snmpapp" if using one of the generic applications (snmpget, snmpwalk, etc). This can also be set using the localCert specifier in a snmp.conf configuration file.

-T peerCert=<certificate-specifier>

If you expect a particular certificate to be presented by the other side then you can use this specifier to indicate the certificate it should present. If it fails to present the expected certificate the client will refuse to open the connection (because doing otherwise could lead to man-in-the-middle attacks). This can also be set using the peerCert specifier in a snmp.conf configuration file.

-T trust_cert=<certificate-specifier>

If you have a trusted CA certificate you wish to anchor trust with, you can use this flag to load a given certificate as a trust anchor. A copy of the certificate must exist within the Net-SNMP certificate storage system or this must point to a complete path name. Also see the "trustCert" snmp.conf configuration token.

-T their_hostname=<name>

If the server's presented certificate can be validating using a trust anchor then their hostname will be checked to ensure their presented hostname matches one that is expected (you don't want to connect to goodhost.example.com and accept a certificate presented by badhost.example.com do you?). This token can specify the exact host name expected to be presented by the remote side, either in a subjectAltName field or in the CommonName field of the server's X.509 certificate.

SNMPv3 with USM Options

These options are specific to using SNMPv3 with the original User-based Security Model (USM).

-3[MmKk] 0xHEXKEY

Sets the keys to be used for SNMPv3 transactions. These options allow you to set the master authentication and encryption keys (-3m and -3M respectively) or set the localized authentication and encryption keys (-3k and -3K respectively). SNMPv3 keys can be either passed in by hand using these flags, or by the use of keys generated from passwords using the -A and -X flags discussed below. For further details on SNMPv3 and its usage of keying information, see the Net-SNMP tutorial web site ( http://www.Net-SNMP.org/tutorial-5/commands/ ). Overrides the defAuthMasterKey (-3m), defPrivMasterKey (-3M), defAuthLocalizedKey (-3k) or defPrivLocalizedKey (-3K) tokens, respectively, in the snmp.conf file, see snmp.conf(5).

-a authProtocol

Set the authentication protocol (MD5 or SHA) used for authenticated SNMPv3 messages. Overrides the defAuthType token in the snmp.conf file.

-A authPassword

Set the authentication pass phrase used for authenticated SNMPv3 messages. Overrides the defAuthPassphrase token in the snmp.conf file. It is insecure to specify pass phrases on the command line, see snmp.conf(5).

-e engineID

Set the authoritative (security) engineID used for SNMPv3 REQUEST messages, given as a hexadecimal string (optionally prefixed by "0x"). It is typically not necessary to specify this engine ID, as it will usually be discovered automatically.

-E engineID

Set the context engineID used for SNMPv3 REQUEST messages scopedPdu, given as a hexadecimal string. If not specified, this will default to the authoritative engineID.

-u secName

Set the securityName used for authenticated SNMPv3 messages. Overrides the defSecurityName token in the snmp.conf file.

-x privProtocol

Set the privacy protocol (DES or AES) used for encrypted SNMPv3 messages. Overrides the defPrivType token in the snmp.conf file. This option is only valid if the Net-SNMP software was build to use OpenSSL.

-X privPassword

Set the privacy pass phrase used for encrypted SNMPv3 messages. Overrides the defPrivPassphrase token in the snmp.conf file. It is insecure to specify pass phrases on the command line, see snmp.conf(5).

-Z boots,time

Set the engineBoots and engineTime used for authenticated SNMPv3 messages. This will initialize the local notion of the agents boots/time with an authenticated value stored in the LCD. It is typically not necessary to specify this option, as these values will usually be discovered automatically.

SNMPv1 and SNMPv2c Options

-c community

Set the community string for SNMPv1/v2c transactions. Overrides the defCommunity token in the snmp.conf file.

AGENT SPECIFICATION

The string AGENT in the SYNOPSIS above specifies the remote SNMP entity with which to communicate. This specification takes the form:

[<transport-specifier>:]<transport-address>

At its simplest, the AGENT specification may consist of a hostname, or an IPv4 address in the standard "dotted quad" notation. In this case, communication will be attempted using UDP/IPv4 to port 161 of the given host. Otherwise, the <transport-address> part of the specification is parsed according to the following table:

<transport-specifier>

<transport-address> format

udp

hostname[:port] or IPv4-address[:port]

tcp

hostname[:port] or IPv4-address[:port]

unix

pathname

ipx

[network]:node[/port]

aal5pvc or pvc

[interface.][VPI.]VCI

udp6 or udpv6 or udpipv6

hostname[:port] or IPv6-address:port or
 '['IPv6-address']'[:port]

tcp6 or tcpv6 or tcpipv6

hostname[:port] or IPv6-address:port or
 '['IPv6-address']'[:port]

Note that <transport-specifier> strings are case-insensitive so that, for example, "tcp" and "TCP" are equivalent. Here are some examples, along with their interpretation:

hostname:161

perform query using UDP/IPv4 datagrams to hostname on port 161. The ":161" is redundant here since that is the default SNMP port in any case.

udp:hostname

identical to the previous specification. The "udp:" is redundant here since UDP/IPv4 is the default transport.

TCP:hostname:1161

connect to hostname on port 1161 using TCP/IPv4 and perform query over that connection. udp6:hostname:10161 perform the query using UDP/IPv6 datagrams to port 10161 on hostname (which will be looked up as an AAAA record).

UDP6:[fe80::2d0:b7ff:fe21:c6c0]

perform the query using UDP/IPv6 datagrams to port 161 at address fe80::2d0:b7ff:fe21:c6c0.

tcpipv6:[::1]:1611

connect to port 1611 on the local host (::1 in IPv6 parlance) using TCP/IPv6 and perform query over that connection.

tls:hostname:10161

dtls:hostname:10161

Connects using SNMP over DTLS or TLS as documented by the ISMS working group (RFCs not yet published as of this date). This will require (and automatically ensures) that the TSM security model is in use. You'll also need to set up trust paths for the certificates presented by the server (see above for descriptions of this).

ssh:hostname:22

Connects using SNMP over SSH as documented by the ISMS working group (RFCs not yet published as of this date). This will require that the TSM security model is in use (--defSecurityModel=tsm).

ipx::00D0B7AAE308

perform query using IPX datagrams to node number 00D0B7AAE308 on the default network, and using the default IPX port of 36879 (900F hexadecimal), as suggested in RFC 1906.

ipx:0AE43409:00D0B721C6C0/1161

perform query using IPX datagrams to port 1161 on node number 00D0B721C6C0 on network number 0AE43409.

unix:/tmp/local-agent

connect to the Unix domain socket /tmp/local-agent, and perform the query over that connection.

/tmp/local-agent

identical to the previous specification, since the Unix domain is the default transport iff the first character of the <transport-address> is a '/'.

alias:myname

perform a connection to the myname alias which needs to be defined in the snmp.conf file using a line like " alias myname udp:127.0.0.1:9161 ". Any type of transport definition can be used as the alias expansion parameter. Aliases are particularly useful for using repeated complex transport strings.

AAL5PVC:100

perform the query using AAL5 PDUs sent on the permanent virtual circuit with VPI=0 and VCI=100 (decimal) on the first ATM adapter in the machine.

PVC:1.10.32

perform the query using AAL5 PDUs sent on the permanent virtual circuit with VPI=10 (decimal) and VCI=32 (decimal) on the second ATM adapter in the machine. Note that "PVC" is a synonym for "AAL5PVC".

Note that not all the transport domains listed above will always be available; for instance, hosts with no IPv6 support will not be able to use udp6 transport addresses, and attempts to do so will result in the error "Unknown host". Likewise, since AAL5 PVC support is only currently available on Linux, it will fail with the same error on other platforms.

MIB PARSING OPTIONS

The Net-SNMP MIB parser mostly adheres to the Structure of Management Information (SMI). As that specification has changed through time, and in recognition of the (ahem) diversity in compliance expressed in MIB files, additional options provide more flexibility in reading MIB files.

-Pc

Toggles whether ASN.1 comments should extend to the end of the MIB source line. Strictly speaking, a second appearance of "--" should terminate the comment, but this breaks some MIB files. The default behaviour (to interpret comments correctly) can also be set with the configuration token commentToEOL.

-Pd

Disables the loading of MIB object DESCRIPTIONs when parsing MIB files. This reduces the amount of memory used by the running application.

-Pe

Toggles whether to show errors encountered when parsing MIB files. These include references to IMPORTed modules and MIB objects that cannot be located in the MIB directory search list. The default behaviour can also be set with the configuration token showMibErrors.

-PR

If the same MIB object (parent name and sub-identifier) appears multiple times in the list of MIB definitions loaded, use the last version to be read in. By default, the first version will be used, and any duplicates discarded. This behaviour can also be set with the configuration token mibReplaceWithLatest.

Such ordering is normally only relevant if there are two MIB files with conflicting object definitions for the same OID (or different revisions of the same basic MIB object).

-Pu

Toggles whether to allow the underline character in MIB object names and other symbols. Strictly speaking, this is not valid SMI syntax, but some vendor MIB files define such names. The default behaviour can also be set with the configuration token mibAllowUnderline.

-Pw

Show various warning messages in parsing MIB files and building the overall OID tree. This can also be set with the configuration directive mibWarningLevel 1

-PW

Show some additional warning messages, mostly relating to parsing individual MIB objects. This can also be set with the configuration directive mibWarningLevel 2

OUTPUT OPTIONS

The format of the output from SNMP commands can be controlled using various parameters of the -O flag. The effects of these sub-options can be seen by comparison with the following default output (unless otherwise specified):

$ snmpget -c public -v 1 localhost sysUpTime.0
SNMPv2-MIB::sysUpTime.0 = Timeticks: (14096763) 1 day, 15:09:27.63

-Oa

Display string values as ASCII strings (unless there is a DISPLAY-HINT defined for the corresponding MIB object). By default, the library attempts to determine whether the value is a printable or binary string, and displays it accordingly.

This option does not affect objects that do have a Display Hint.

-Ob

Display table indexes numerically, rather than trying to interpret the instance subidentifiers as string or OID values:

    $ snmpgetnext -c public -v 1 localhost vacmSecurityModel
    SNMP-VIEW-BASED-ACM-MIB::vacmSecurityModel.0."wes" = xxx
    $ snmpgetnext -c public -v 1 -Ob localhost vacmSecurityModel
    SNMP-VIEW-BASED-ACM-MIB::vacmSecurityModel.0.3.119.101.115 = xxx

-Oe

Removes the symbolic labels from enumeration values:

    $ snmpget -c public -v 1 localhost ipForwarding.0
    IP-MIB::ipForwarding.0 = INTEGER: forwarding(1)
    $ snmpget -c public -v 1 -Oe localhost ipForwarding.0
    IP-MIB::ipForwarding.0 = INTEGER: 1

-OE

Modifies index strings to escape the quote characters:

    $ snmpgetnext -c public -v 1 localhost vacmSecurityModel
    SNMP-VIEW-BASED-ACM-MIB::vacmSecurityModel.0."wes" = xxx
    $ snmpgetnext -c public -v 1 -OE localhost vacmSecurityModel
    SNMP-VIEW-BASED-ACM-MIB::vacmSecurityModel.0.\"wes\" = xxx

This allows the output to be reused in shell commands.

-Of

Include the full list of MIB objects when displaying an OID:

.iso.org.dod.internet.mgmt.mib-2.system.sysUpTime.0 =

Timeticks: (14096763) 1 day, 15:09:27.63

-On

Displays the OID numerically:
.1.3.6.1.2.1.1.3.0 = Timeticks: (14096763) 1 day, 15:09:27.63

-Oq

Removes the equal sign and type information when displaying varbind values:
SNMPv2-MIB::sysUpTime.0 1:15:09:27.63

-OQ

Removes the type information when displaying varbind values:
SNMPv2-MIB::sysUpTime.0 = 1:15:09:27.63

-Os

Display the MIB object name (plus any instance or other subidentifiers):
sysUpTime.0 = Timeticks: (14096763) 1 day, 15:09:27.63

-OS

Display the name of the MIB, as well as the object name:
SNMPv2-MIB::sysUpTime.0 = Timeticks: (14096763) 1 day, 15:09:27.63

This is the default OID output format.

-Ot

Display TimeTicks values as raw numbers:
SNMPv2-MIB::sysUpTime.0 = 14096763

-OT

If values are printed as Hex strings, display a printable version as well.

-Ou

Display the OID in the traditional UCD-style (inherited from the original CMU code). That means removing a series of "standard" prefixes from the OID, and displaying the remaining list of MIB object names (plus any other subidentifiers):
system.sysUpTime.0 = Timeticks: (14096763) 1 day, 15:09:27.63

-OU

Do not print the UNITS suffix at the end of the value.

-Ov

Display the varbind value only, not the OID:

    $ snmpget -c public -v 1 -Ov localhost ipForwarding.0
    INTEGER: forwarding(1)

-Ox

Display string values as Hex strings (unless there is a DISPLAY-HINT defined for the corresponding MIB object). By default, the library attempts to determine whether the value is a printable or binary string, and displays it accordingly.

This option does not affect objects that do have a Display Hint.

-OX

Display table indexes in a more "program like" output, imitating a traditional array-style index format:

    $ snmpgetnext -c public -v 1 localhost ipv6RouteTable
    IPv6-MIB::ipv6RouteIfIndex.63.254.1.0.255.0.0.0.0.0.0.0.0.0.0.0.64.1 = INTEGER: 2
    $ snmpgetnext -c public -v 1 -OX localhost ipv6RouteTable
    IPv6-MIB::ipv6RouteIfIndex[3ffe:100:ff00:0:0:0:0:0][64][1] = INTEGER: 2

Most of these options can also be configured via configuration tokens. See the snmp.conf(5) manual page for details.

LOGGING OPTIONS

The mechanism and destination to use for logging of warning and error messages can be controlled by passing various parameters to the -L flag.

-Le

Log messages to the standard error stream.

-Lf FILE

Log messages to the specified file.

-Lo

Log messages to the standard output stream.

-Ls FACILITY

Log messages via syslog, using the specified facility ('d' for LOG_DAEMON, 'u' for LOG_USER, or '0'-'7' for LOG_LOCAL0 through LOG_LOCAL7).

There are also "upper case" versions of each of these options, which allow the corresponding logging mechanism to be restricted to certain priorities of message. Using standard error logging as an example:

-LE pri

will log messages of priority 'pri' and above to standard error.

-LE p1-p2

will log messages with priority between 'p1' and 'p2' (inclusive) to standard error.

For -LF and -LS the priority specification comes before the file or facility token. The priorities recognised are:

0 or ! for LOG_EMERG,
1 or a for LOG_ALERT,
2 or c for LOG_CRIT,
3 or e for LOG_ERR,
4 or w for LOG_WARNING,
5 or n for LOG_NOTICE,
6 or i for LOG_INFO, and
7 or d for LOG_DEBUG.

Normal output is (or will be!) logged at a priority level of LOG_NOTICE

INPUT OPTIONS

The interpretation of input object names and the values to be assigned can be controlled using various parameters of the -I flag. The default behaviour will be described at the end of this section.

-Ib

specifies that the given name should be regarded as a regular expression, to match (case-insensitively) against object names in the MIB tree. The "best" match will be used - calculated as the one that matches the closest to the beginning of the node name and the highest in the tree. For example, the MIB object vacmSecurityModel could be matched by the expression vacmsecuritymodel (full name, but different case), or vacm.*model (regexp pattern).

Note that '.' is a special character in regular expression patterns, so the expression cannot specify instance subidentifiers or more than one object name. A "best match" expression will only be applied against single MIB object names. For example, the expression sys*ontact.0 would not match the instance sysContact.0 (although sys*ontact would match sysContact). Similarly, specifying a MIB module name will not succeed (so SNMPv2-MIB::sys.*ontact would not match either).

-Ih

disables the use of DISPLAY-HINT information when assigning values. This would then require providing the raw value:
snmpset ... HOST-RESOURCES-MIB::hrSystemDate.0

              x "07 D2 0C 0A 02 04 06 08"
instead of a formatted version:
snmpset ... HOST-RESOURCES-MIB::hrSystemDate.0

              = 2002-12-10,2:4:6.8

-Ir

disables checking table indexes and the value to be assigned against the relevant MIB definitions. This will (hopefully) result in the remote agent reporting an invalid request, rather than checking (and rejecting) this before it is sent to the remote agent.
  Local checks are more efficient (and the diagnostics provided also tend to be more precise), but disabling this behaviour is particularly useful when testing the remote agent.

-IR

enables "random access" lookup of MIB names. Rather than providing a full OID path to the desired MIB object (or qualifying this object with an explicit MIB module name), the MIB tree will be searched for the matching object name. Thus .iso.org.dod.internet.mib-2.system.sysDescr.0 (or SNMPv2-MIB::sysDescr.0) can be specified simply as sysDescr.0.

Warning:

Since MIB object names are not globally unique, this approach may return a different MIB object depending on which MIB files have been loaded.

The MIB-MODULE::objectName syntax has the advantage of uniquely identifying a particular MIB object, as well as being slightly more efficient (and automatically loading the necessary MIB file if necessary).

-Is SUFFIX

adds the specified suffix to each textual OID given on the command line. This can be used to retrieve multiple objects from the same row of a table, by specifying a common index value.

-IS PREFIX

adds the specified prefix to each textual OID given on the command line. This can be used to specify an explicit MIB module name for all objects being retrieved (or for incurably lazy typists).

-Iu

enables the traditional UCD-style approach to interpreting input OIDs. This assumes that OIDs are rooted at the 'mib-2' point in the tree (unless they start with an explicit '.' or include a MIB module name). So the sysDescr instance above would be referenced as system.sysDescr.0.

Object names specified with a leading '.' are always interpreted as "fully qualified" OIDs, listing the sequence of MIB objects from the root of the MIB tree. Such objects and those qualified by an explicit MIB module name are unaffected by the -Ib, -IR and -Iu flags.

Otherwise, if none of the above input options are specified, the default behaviour for a "relative" OID is to try and interpret it as an (implicitly) fully qualified OID, then apply "random access" lookup (-IR), followed by "best match" pattern matching (-Ib).

ENVIRONMENT VARIABLES

PREFIX

The standard prefix for object identifiers (when using UCD-style output). Defaults to .iso.org.dod.internet.mgmt.mib-2

MIBS

The list of MIBs to load. Defaults to SNMPv2-TC:SNMPv2-MIB:IF-MIB:IP-MIB:TCP-MIB:UDP-MIB:SNMP-VACM-MIB. Overridden by the -m option.

MIBDIRS

The list of directories to search for MIBs. Defaults to /usr/share/snmp/mibs. Overridden by the -M option.

FILES

/etc/snmp/snmpd.conf

Agent configuration file. See snmpd.conf(5).

/etc/snmp/snmp.conf

~/.snmp/snmp.conf

Application configuration files. See snmp.conf(5).