| Net_SNMP_util(3pm) | User Contributed Perl Documentation | Net_SNMP_util(3pm) |
Net_SNMP_util - SNMP utilities based on Net::SNMP
The Net_SNMP_util module implements SNMP utilities using the Net::SNMP module. It implements snmpget, snmpgetnext, snmpwalk, snmpset, snmptrap, and snmpgetbulk. The Net_SNMP_util module assumes that the user has a basic understanding of the Simple Network Management Protocol and related network management concepts.
The Net_SNMP_util module simplifies SNMP queries even more than Net::SNMP alone. Easy-to-use "get", "getnext", "walk", "set", "trap", and "getbulk" routines are provided, hiding all the details of a SNMP query.
community@host:port:timeout:retries:backoff:version
If the community is left off, it defaults to "public". If the port is left off, it defaults to 161 for everything but snmptrap(). The snmptrap() routine uses a default port of 162. Timeout and retries defaults to whatever Net::SNMP uses, currently 5.0 seconds and 1 retry (2 tries total). The backoff parameter is currently unimplemented. The version parameter defaults to SNMP version 1. Some SNMP values such as 64-bit counters have to be queried using SNMP version 2. Specifying "2" or "2c" as the version parameter will accomplish this. The snmpgetbulk routine is only supported in SNMP version 2 and higher. Additional security features are available under SNMP version 3.
Some machines have additional security features that only allow SNMP queries to come from certain IP addresses. If the host doing the query has multiple interfaces, it may be necessary to specify the interface the query should come from. The port parameter is further broken down into
remote_port!local_address!local_port
Here are some examples:
somehost
somehost:161
somehost:161!192.168.2.4!4000 use 192.168.2.4 and port 4000 as source
somehost:!192.168.2.4 use 192.168.2.4 as source
somehost:!!4000 use port 4000 as source
Most people will only need to use the first form ("somehost").
Several functions are provided to manage the mapping table. Mapping entries can be added directly, SNMP MIB files can be read, and a cache file with the text-to-OBJECT-IDENTIFIER mappings are maintained. By default, the file "OID_cache.txt" is loaded, but it can by changed by setting the variable $Net_SNMP_util::CacheFile to the desired file name. The functions to manipulate the mappings are:
snmpmapOID Add a textual OID mapping directly
snmpMIB_to_OID Read a SNMP MIB file
snmpLoad_OID_Cache Load an OID-mapping cache file
snmpQueue_MIB_File Queue a SNMP MIB file for loading on demand
[-port => $port,]
[-localaddr => $localaddr,]
[-localport => $localport,]
[-version => $version,]
[-domain => $domain,]
[-timeout => $seconds,]
[-retries => $count,]
[-maxmsgsize => $octets,]
[-debug => $bitmask,]
[-community => $community,] # v1/v2c
[-username => $username,] # v3
[-authkey => $authkey,] # v3
[-authpassword => $authpasswd,] # v3
[-authprotocol => $authproto,] # v3
[-privkey => $privkey,] # v3
[-privpassword => $privpasswd,] # v3
[-privprotocol => $privproto,] # v3
[-contextengineid => $engine_id,] # v3
[-contextname => $name,] # v3
Please see the documentation for Net::SNMP for a description of these parameters.
@result = snmpget(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
[\%param_hash],
@oids
);
This function performs a SNMP get-request query to gather data from the remote agent on the host specified. The message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetRequest-PDU in the same order that it held in the original list.
The requested values are returned in an array in the same order as they were requested. In scalar context the first requested value is returned.
@result = snmpgetnext(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
[\%param_hash],
@oids
);
This function performs a SNMP get-next-request query to gather data from the remote agent on the host specified. The message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetNextRequest-PDU in the same order that it held in the original list.
The requested values are returned in an array in the same order as they were requested. The OBJECT IDENTIFIER number is added as a prefix to each value using a colon as a separator, like '1.3.6.1.2.1.2.2.1.2.1:ethernet'. In scalar context the first requested value is returned.
@result = snmpgetbulk(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
$nonrepeaters,
$maxrepetitions,
[\%param_hash],
@oids
);
This function performs a SNMP get-bulk-request query to gather data from the remote agent on the host specified.
The requested values are returned in an array in the same order as they were requested.
NOTE: This function can only be used when the SNMP version is set to SNMPv2c or SNMPv3.
@result = snmpwalk(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
[\%param_hash],
@oids
);
This function performs a sequence of SNMP get-next-request or get-bulk-request (if the SNMP version is 2 or higher) queries to gather data from the remote agent on the host specified. The initial message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetNextRequest-PDU in the same order that it held in the original list. Queries continue until all the returned OBJECT IDENTIFIERs are no longer a child of the base OBJECT IDENTIFIERs.
The requested values are returned in an array in the same order as they were requested. The OBJECT IDENTIFIER number is added as a prefix to each value using a colon as a separator, like '1.3.6.1.2.1.2.2.1.2.1:ethernet'. If only one OBJECT IDENTIFIER is requested, just the "instance" part of the OBJECT IDENTIFIER is added as a prefix, like '1:ethernet', '2:ethernet', '3:fddi'.
@result = snmpset(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
[\%param_hash],
$oid1, $type1, $value1,
[$oid2, $type2, $value2 ...]
);
This function is used to modify data on the remote agent using a SNMP set-request. The message is built using the list of values consisting of groups of an OBJECT IDENTIFIER, an object type, and the actual value to be set. The object type can be one of the following strings:
integer | int
string | octetstring | octet string
oid | object id | object identifier
ipaddr | ip addr4ess
timeticks
uint | uinteger | uinteger32 | unsigned int | unsigned integer | unsigned integer32
counter | counter 32
counter64
gauge | gauge32
The object type may also be an octet corresponding to the ASN.1 type. See the Net::SNMP documentation for more information.
The requested values are returned in an array in the same order as they were requested. In scalar context the first requested value is returned.
@result = snmptrap(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
$enterprise,
$agentaddr,
$generictrap,
$specifictrap,
[\%param_hash],
$oid1, $type1, $value1,
[$oid2, $type2, $value2 ...]
);
This function sends a SNMP trap to the remote manager on the host specified. The message is built using the list of values consisting of groups of an OBJECT IDENTIFIER, an object type, and the actual value to be set. The object type can be one of the following strings:
integer | int
string | octetstring | octet string
oid | object id | object identifier
ipaddr | ip addr4ess
timeticks
uint | uinteger | uinteger32 | unsigned int | unsigned integer | unsigned integer32
counter | counter 32
counter64
gauge | gauge32
The object type may also be an octet corresponding to the ASN.1 type. See the Net::SNMP documentation for more information.
A true value is returned if sending the trap is successful. The undefined value is returned when a failure has occurred.
When the trap is sent as SNMPv2c, the $enterprise, $agentaddr, $generictrap, and $specifictrap arguments are ignored. Furthermore, the first two (oid, type, value) tuples should be:
NOTE: This function can only be used when the SNMP version is set to SNMPv1 or SNMPv2c.
$result = snmpmaptable(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
\&function,
[\%param_hash],
@oids
);
This function performs a sequence of SNMP get-next-request or get-bulk-request (if the SNMP version is 2 or higher) queries to gather data from the remote agent on the host specified. The initial message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetNextRequest-PDU in the same order that it held in the original list. Queries continue until all the returned OBJECT IDENTIFIERs are no longer a child of the base OBJECT IDENTIFIERs. The OBJECT IDENTIFIERs must correspond to column entries for a conceptual row in a table. They may however be columns in different tables as long as each table is indexed the same way.
The number of rows in the table is returned on success. The undefined value is returned when a failure has occurred.
$result = snmpmaptable4(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
\&function,
$maxrepetitions,
[\%param_hash],
@oids
);
This function performs a sequence of SNMP get-next-request or get-bulk-request (if the SNMP version is 2 or higher) queries to gather data from the remote agent on the host specified. The initial message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetNextRequest-PDU in the same order that it held in the original list. Queries continue until all the returned OBJECT IDENTIFIERs are no longer a child of the base OBJECT IDENTIFIERs. The OBJECT IDENTIFIERs must correspond to column entries for a conceptual row in a table. They may however be columns in different tables as long as each table is indexed the same way.
The number of rows in the table is returned on success. The undefined value is returned when a failure has occurred.
@result = snmpwalkhash(
[community@]host[:port[:timeout[:retries[:backoff[:version]]]]],
\&function(),
[\%param_hash],
@oids,
[\%hash]
);
This function performs a sequence of SNMP get-next-request or get-bulk-request (if the SNMP version is 2 or higher) queries to gather data from the remote agent on the host specified. The message is built using the list of OBJECT IDENTIFIERs passed as an array. Each OBJECT IDENTIFIER is placed into a single SNMP GetNextRequest-PDU in the same order that it held in the original list. Queries continue until all the returned OBJECT IDENTIFIERs are outside of the tree specified by the initial OBJECT IDENTIFIERs.
The \&function is called once for every returned value. It is passed a reference to a hash, the hostname, the textual OBJECT IDENTIFIER, the dotted-numberic OBJECT IDENTIFIER, the instance, the value and the requested textual OBJECT IDENTIFIER. That function can customize the result so the values can be extracted later by hosts, by oid_names, by oid_numbers, by instances... like these:
$hash{$host}{$name}{$inst} = $value;
$hash{$host}{$oid}{$inst} = $value;
$hash{$name}{$inst} = $value;
$hash{$oid}{$inst} = $value;
$hash{$oid . '.' . $ints} = $value;
$hash{$inst} = $value;
...
If the last argument to snmpwalkhash is a reference to a hash, that hash reference is passed to the passed-in function instead of a local hash reference. That way the function can look up other objects unrelated to the current invocation of snmpwalkhash.
The snmpwalkhash routine returns the hash.
snmpmapOID(
$text1, $oid1,
[ $text2, $oid2 ...]
);
This routine adds entries to the table that maps textual representation of OBJECT IDENTIFIERs to their dotted notation. For example,
snmpmapOID('ciscoCPU', '1.3.6.1.4.1.9.9.109.1.1.1.1.5.1');
allows the string 'ciscoCPU' to be used as an OBJECT IDENTIFIER in any SNMP query routine.
This routine doesn't return anything.
$result = snmpLoad_OID_Cache(
$file
);
This routine opens the file named by the $file argument and reads it. The file should contain text, OBJECT IDENTIFIER pairs, one pair per line. It adds the pairs as entries to the table that maps textual representation of OBJECT IDENTIFIERs to their dotted notation. Blank lines and anything after a '#' or between '--' is ignored.
This routine returns 0 on success and -1 if the $file could not be opened.
$result = snmpMIB_to_OID(
$file
);
This routine opens the file named by the $file argument and reads it. The file should be an SNMP Management Information Base (MIB) file that describes OBJECT IDENTIFIERs supported by an SNMP agent. per line. It adds the textual representation of the OBJECT IDENTIFIERs to the text-to-OID mapping table.
This routine returns the number of entries added to the table or -1 if the $file could not be opened.
snmpQueue_MIB_File(
$file1,
[$file2, ...]
);
This routine queues the list of SNMP MIB files for later processing. Whenever a text-to-OBJECT IDENTIFIER lookup fails, the list of queued MIB files is consulted. If it isn't empty, the first MIB file in the list is removed and passed to snmpMIB_to_OID(). The lookup is attempted again, and if that still fails the next MIB file in the list is removed and passed to snmpMIB_to_OID(). This process continues until the lookup succeeds or the list is exhausted.
This routine doesn't return anything.
The Net_SNMP_util module uses the Exporter module to export useful constants and subroutines. These exportable symbols are defined below and follow the rules and conventions of the Exporter module (see Exporter).
This example gets the sysUpTime from a remote host.
#! /usr/local/bin/perl
use strict;
use Net_SNMP_util;
my ($host, $ret)
$host = shift || 'localhost';
$ret = snmpget($host, 'sysUpTime');
print("sysUpTime for $host is $ret\n");
exit 0;
This example sets the sysContact information on the remote host to "Help Desk x911". The parameters passed to the snmpset function are for the demonstration of syntax only. These parameters will need to be set according to the SNMPv3 parameters of the remote host used by the script.
#! /usr/local/bin/perl
use strict;
use Net_SNMP_util;
my($host, %v3hash, $ret);
$host = shift || 'localhost';
$v3hash{'-version'} = 'snmpv3';
$v3hash{'-username'} = 'myv3Username';
$v3hash{'-authkey'} = '0x05c7fbde31916f64da4d5b77156bdfa7';
$v3hash{'-authprotocol'} = 'md5';
$v3hash{'-privkey'} = '0x93725fd3a02a48ce02df4e065a1c1746';
$ret = snmpset($host, \%v3hash, 'sysContact', 'string', 'Help Desk x911');
print "sysContact on $host is now $ret\n";
exit 0;
This example gets the contents of the ifTable by sending get-bulk-requests until the responses are no longer part of the ifTable. The ifTable can also be retrieved using "snmpmaptable".
#! /usr/local/bin/perl
use strict;
use Net_SNMP_util;
my($host, @ret, $oid, $val);
$host = shift || 'localhost';
@ret = snmpwalk($host . ':::::2', 'ifTable');
foreach $val (@ret) {
($oid, $val) = split(':', $val, 2);
print "$oid => $val\n";
}
exit 0;
This example collects a table containing the columns ifDescr, ifInOctets, and ifOutOctets. A printing function is called once per row.
#! /usr/local/bin/perl
use strict;
use Net_SNMP_util;
sub printfun($$$$) {
my($inst, $desc, $in, $out) = @_;
printf "%3d %-52.52s %10d %10d\n", $inst, $desc, $in, $out;
}
my($host, @ret);
$host = shift || 'localhost';
printf "%-3s %-52s %10s %10s\n", "Int", "Description", "In", "Out";
@ret = snmpmaptable($host . ':::::2', \&printfun,
'ifDescr', 'ifInOctets', 'ifOutOctets');
exit 0;
Mike Mitchell <Mike.Mitchell@sas.com>
The original concept for this module was based on SNMP_Session.pm written by Simon Leinen <simon@switch.ch>
Copyright (c) 2007 Mike Mitchell. All rights reserved. This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
| 2022-11-26 | perl v5.36.0 |