TUT:Simple Application - Revision history

Stephen at 15:20, 11 November 2014

2014-11-11T15:20:37Z

Stephen at 15:17, 11 November 2014

2014-11-11T15:17:46Z

Stephen at 15:15, 11 November 2014

2014-11-11T15:15:08Z

Nij25 at 04:45, 7 July 2014

2014-07-07T04:45:18Z

Newacct at 15:43, 26 June 2010

2010-06-26T15:43:02Z

Wes: /* Homework: */ link to the new command line calling order page

2010-02-18T00:22:58Z

‎Homework:: link to the new command line calling order page

Igor at 18:20, 13 September 2007

2007-09-13T18:20:37Z

Rstory: update demo password

2007-04-25T13:17:18Z

update demo password

@@ Line 1: / Line 1: @@
-Here we discuss how to write a simple application. It's only purpose is to retrieve the value of a variable from a remote host.
+Here we discuss how to write a simple application. Its only purpose is to retrieve the value of a variable from a remote host.
 {{TUT:File-Table-Top-and-basics}}
@@ Line 11: / Line 11: @@
-Next, we'll set up some local definitions that you can toggle if you want to use SNMPv3 or SNMPv1. By default, we're setting up for SNMPv3 here (which is more complex, so make sure you've read about the  SNMPv3 Options  first. If you don't want to deal with SNMPv3 for now, turn the #define statement below to #undef.
+Next, we'll set up some local definitions that you can toggle if you want to use SNMPv3 or SNMPv1. By default, we're setting up for SNMPv3 here (which is more complex) so make sure you've read about the  SNMPv3 Options  first. If you don't want to deal with SNMPv3 for now, turn the #define statement below to #undef.
    /* change the word "define" to "undef" to try the (insecure) SNMPv1 version */
@@ Line 48: / Line 48: @@
      int status;
-Then, the first thing we must do is to inialize the snmp library:
+Then, the first thing we must do is to initialize the snmp library:
      /*
@@ Line 55: / Line 55: @@
      init_snmp("snmpapp");
-Next, we'll inialize a session that describes who we want to talk to, what version of SNMP we want to use, how to authenticate to it, etc. A full definition of this session can be found in the net-snmp/snmp_api.h header file.
+Next, we'll initialize a session that describes who we want to talk to, what version of SNMP we want to use, how to authenticate to it, etc. A full definition of this session can be found in the net-snmp/snmp_api.h header file.
 We've picked SNMPv3 by default above, which is a bit more complex to understand so make sure you've read
@@ Line 111: / Line 111: @@
      #endif /* SNMPv1 */
-After we have established the session, we then need to open
+After we have established the session, we then need to open it. Opening it returns a pointer to another session that we should use
 it. Opening it returns a pointer to another session that we should use
 for all our future calls:

@@ Line 142: / Line 142: @@
      pdu = snmp_pdu_create(SNMP_MSG_GET);
-So, let's fill it with our requested oid. Let's get the system.sysDescr.0 variable for this example. There are numerious ways you could create the oid in question. You could put in the numerical unsigned integer values yourself into the anOID array we created above, or you could use one of the following function calls to do it. We recommend the first one (get_node), as it is the most powerful and accepts more types of OIDs.
+So, let's fill it with our requested oid. Let's get the system.sysDescr.0 variable for this example. There are numerous ways you could create the oid in question. You could put in the numerical unsigned integer values yourself into the anOID array we created above, or you could use one of the following function calls to do it. We recommend the first one (get_node), as it is the most powerful and accepts more types of OIDs.
      read_objid(".1.3.6.1.2.1.1.1.0", anOID, &anOID_len);
@@ Line 162: / Line 162: @@
      status = snmp_synch_response(ss, pdu, &response);
-Now we can examine the information, assuming our request was fulfilled
+Now we can examine the information, assuming our request was fulfilled properly. If not, we'll print the error that caused the problem:
 properly. If not, we'll print the error that caused the problem:
      /*
@@ Line 173: / Line 172: @@
         */
-Lets print the pdu's variable to the terminal using the print_variable routine:
+Let's print the pdu's variable to the terminal using the print_variable routine:
        for(vars = response->variables; vars; vars = vars->next_variable)
          print_variable(vars->name, vars->name_length, vars);
-Then, for kicks, lets get the information and manipulate it ourselves (checking to make sure its the type we're expecting (a string) first):
+Then, for kicks, lets get the information and manipulate it ourselves (checking to make sure it's the type we're expecting (a string) first):
        /* manipulate the information ourselves */
@@ Line 225: / Line 224: @@
    } /* main() */
-Ok, we're done. lets compile it (using the Makefile distributed above):
+Ok, we're done. Let's compile it (using the Makefile distributed above):
    % '''make snmpdemoapp'''

@@ Line 100: / Line 100: @@
+     }
-     #else /* we'll use the insecure (but simplier) SNMPv1 */
+     #else /* we'll use the insecure (but simpler) SNMPv1 */
      /* set the SNMP version number */
@@ Line 134: / Line 134: @@
 when we request information. In this case, we're going to create a
 SNMP-GET pdu, which is what the snmpget program uses, for instance. It
-retrieves a value for each oid that you initalize it with.
+retrieves a value for each oid that you initialize it with.
      /*

@@ Line 32: / Line 32: @@
 * '''struct snmp_session:''' A structure that holds information about who we're going to be talking to. We need to declare 2 of these, one to fill with information, and second which is a pointer returned by the library.
-* '''struct snmp_pdu:''' This structure will hold all of the information that we're going to send to the remote host. We'll declare a second for the information they they are going to send back.
+* '''struct snmp_pdu:''' This structure will hold all of the information that we're going to send to the remote host. We'll declare a second for the information that they are going to send back.
 * '''oid:''' An OID is going to hold the location of the information which we want to retrieve. It'll need a size as well.

@@ Line 184: / Line 184: @@
          int count=1;
          if (vars->type == ASN_OCTET_STR) {
-           char *sp = (char *)malloc(1 + vars->val_len);
+           char *sp = malloc(1 + vars->val_len);
            memcpy(sp, vars->val.string, vars->val_len);
            sp[vars->val_len] = '\0';

← Older revision		Revision as of 00:22, 18 February 2010
Line 243:		Line 243:

	{{TUT:LIST}}		{{TUT:LIST}}
		+
		+	=== Follow-on Reading ===
		+
		+	Internally the snmp library does a lot of things for you. You can learn about what's happening internally by looking at the [[Command Line Calling Order]] page.

@@ Line 18: / Line 18: @@
    #ifdef DEMO_USE_SNMP_VERSION_3
    #include "net-snmp/transform_oids.h"
-   const char *our_v3_passphrase = "The UCD Demo Password";
+   const char *our_v3_passphrase = "The Net-SNMP Demo Password";
    #endif
@@ Line 87: / Line 87: @@
      /* set the authentication key to a MD5 hashed version of our
-        passphrase "The UCD Demo Password" (which must be at least 8
+        passphrase "The Net-SNMP Demo Password" (which must be at least 8
         characters long) */
      if (generate_Ku(session.securityAuthProto,