1SNMP_CONFIG(5) Net-SNMP SNMP_CONFIG(5)
2
6 snmp_config - handling of Net-SNMP configuration files
7
9 The Net-SNMP package uses various configuration files to configure its
10 applications. This manual page merely describes the overall nature of
11 them, so that the other manual pages don't have to.
12
14 First off, there are numerous places that configuration files can be
15 found and read from. By default, the applications look for configura‐
16 tion files in the following 4 directories, in order: /etc/snmp,
17 /usr/share/snmp, /usr/lib(64)/snmp, and $HOME/.snmp. In each of these
18 directories, it looks for files snmp.conf, snmpd.conf and/or sn‐
19 mptrapd.conf, as well as snmp.local.conf, snmpd.local.conf and/or sn‐
20 mptrapd.local.conf. *.local.conf are always read last. In this manner,
21 there are 8 default places a configuration file can exist for any given
22 configuration file type.
23 Additionally, the above default search path can be overridden by set‐
25 ting the environment variable SNMPCONFPATH to a colon-separated list of
26 directories to search for. The path for the persistent data should be
27 included when running applications that use persistent storage, such as
28 snmpd.
29 Applications will read persistent configuration files in the following
31 order of preference:
32 file in SNMP_PERSISTENT_FILE environment variable
34 directories in SNMPCONFPATH environment variable
35 directory defined by persistentDir snmp.conf variable
36 directory in SNMP_PERSISTENT_DIR environment variable
37 default /var/lib/net-snmp directory
38 Finally, applications will write persistent configuration files in the
40 following order of preference:
41 file in SNMP_PERSISTENT_FILE environment variable
43 directory defined by persistentDir snmp.conf variable
44 directory in SNMP_PERSISTENT_DIR environment variable
45 default /var/lib/net-snmp directory
46 Note: When using SNMP_PERSISTENT_FILE, the filename should match the
48 application name. For example, /var/net-snmp/snmpd.conf.
49
51 Each application may use multiple configuration files, which will con‐
52 figure various different aspects of the application. For instance, the
53 SNMP agent (snmpd) knows how to understand configuration directives in
54 both the snmpd.conf and the snmp.conf files. In fact, most applica‐
55 tions understand how to read the contents of the snmp.conf files.
56 Note, however, that configuration directives understood in one file may
57 not be understood in another file. For further information, read the
58 associated manual page with each configuration file type. Also, most
59 of the applications support a -H switch on the command line that will
60 list the configuration files it will look for and the directives in
61 each one that it understands.
62 The snmp.conf configuration file is intended to be a application suite
64 wide configuration file that supports directives that are useful for
65 controlling the fundamental nature of all of the SNMP applications,
66 such as how they all manipulate and parse the textual SNMP MIB files.
67
69 It's possible to switch in mid-file the configuration type that the
70 parser is supposed to be reading. Since that sentence doesn't make
71 much sense, lets give you an example: say that you wanted to turn on
72 packet dumping output for the agent by default, but you didn't want to
73 do that for the rest of the applications (ie, snmpget, snmpwalk, ...).
74 Normally to enable packet dumping in the configuration file you'd need
75 to put a line like:
76 dumpPacket true
78 into the snmp.conf file. But, this would turn it on for all of the ap‐
80 plications. So, instead, you can put the same line in the snmpd.conf
81 file so that it only applies to the snmpd daemon. However, you need to
82 tell the parser to expect this line. You do this by putting a special
83 type specification token inside a [] set. In other words, inside your
84 snmpd.conf file you could put the above snmp.conf directive by adding a
85 line like so:
86 [snmp] dumpPacket true
88 This tells the parser to parse the above line as if it were inside a
90 snmp.conf file instead of an snmpd.conf file. If you want to parse a
91 bunch of lines rather than just one then you can make the context
92 switch apply to the remainder of the file or until the next context
93 switch directive by putting the special token on a line by itself:
94 # make this file handle snmp.conf tokens:
96 [snmp]
97 dumpPacket true
98 logTimestamp true
99 # return to our original snmpd.conf tokens:
100 [snmpd]
101 rocommunity mypublic
102 The same approach can be used to set configuration directives for a
104 particular client application (or group of applications). For example,
105 any program that uses the 'snmp_parse_args()' call to handle command-
106 line arguments (including the standard command-line tools shipped as
107 part of the Net-SNMP distributions) will automatically read the config
108 file 'snmpapp.conf'. To set library-level settings for these applica‐
109 tions (but not other more-specific tools), use configuration such as
110 the following:
111 [snmp] defCommunity myCommunity
113 for a single directive, or
115 # make this file handle snmp.conf tokens:
117 [snmp]
118 defCommunity myCommunity
119 defVersion 2c
120 # return to our original snmpapp.conf tokens:
121 [snmpapp]
122 for multiple settings. Similarly for any other application token (as
124 passed to init_snmp()).
125
127 Any lines beginning with the character '#' in the configuration files
128 are treated as a comment and are not parsed.
129
131 It is possible to include other configuration files for processing dur‐
132 ing normal configuration file processing.:
133 # include site specific config
135 includeFile site.conf
136 This will load the specified configuration file. The
138 path to file must be either absolute, starting with '/',
139 or relative. The relative path is then relative to the directory
140 where the parent file with 'includeFile' directive resides.
141 The included file name does not need to have '.conf' suffix.
143 # include a all *.conf files in a directory
145 includeDir /etc/snmp/config.d
146 This will search specified directory for all files with '.conf'
148 suffix and process them as if they were included using includeFile
149 directive. The configuration files are not processed in any particular
150 order.
151 The specified directory must be absolute directory path.
153
155 Information about writing C code that makes use of this system in ei‐
156 ther the agent's MIB modules or in applications can be found in the
157 netsnmp_config_api(3) manual page.
158
160 snmpconf(1), netsnmp_config_api(3), snmp.conf(5), snmpd.conf(5)
161V5.9.3 08 Mar 2010 SNMP_CONFIG(5)