Makefile
#
# Warning: you may need more libraries than are included here on the
# build line. The agent frequently needs various libraries in order
# to compile pieces of it, but is OS dependent and we can't list all
# the combinations here. Instead, look at the libraries that were
# used when linking the snmpd master agent and copy those to this
# file.
#
CC=gcc
OBJS1=snmpdemoapp.o
OBJS2=example-demon.o nstAgentSubagentObject.o
OBJS3=asyncapp.o
TARGETS=example-demon snmpdemoapp asyncapp
CFLAGS=-I. `net-snmp-config --cflags`
BUILDLIBS=`net-snmp-config --libs`
BUILDAGENTLIBS=`net-snmp-config --agent-libs`
# shared library flags (assumes gcc)
DLFLAGS=-fPIC -shared
all: $(TARGETS)
snmpdemoapp: $(OBJS1)
$(CC) -o snmpdemoapp $(OBJS1) $(BUILDLIBS)
asyncapp: $(OBJS3)
$(CC) -o asyncapp $(OBJS3) $(BUILDLIBS)
example-demon: $(OBJS2)
$(CC) -o example-demon $(OBJS2) $(BUILDAGENTLIBS)
clean:
rm $(OBJS2) $(OBJS2) $(TARGETS)
nstAgentPluginObject.so: nstAgentPluginObject.c Makefile
$(CC) $(CFLAGS) $(DLFLAGS) -c -o nstAgentPluginObject.o nstAgentPluginObject.c
$(CC) $(CFLAGS) $(DLFLAGS) -o nstAgentPluginObject.so nstAgentPluginObject.o
C code
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <string.h>
/* change the word "define" to "undef" to try the (insecure) SNMPv1 version */
#define DEMO_USE_SNMP_VERSION_3
#ifdef DEMO_USE_SNMP_VERSION_3
const char *our_v3_passphrase = "The Net-SNMP Demo Password";
#endif
int main(int argc, char ** argv)
{
netsnmp_session session, *ss;
netsnmp_pdu *pdu;
netsnmp_pdu *response;
oid anOID[MAX_OID_LEN];
size_t anOID_len;
netsnmp_variable_list *vars;
int status;
int count=1;
/*
* Initialize the SNMP library
*/
init_snmp("snmpdemoapp");
/*
* Initialize a "session" that defines who we're going to talk to
*/
snmp_sess_init( &session ); /* set up defaults */
session.peername = strdup("test.net-snmp.org"); /* Remote IP Address */
/* set up the authentication parameters for talking to the server */
#ifdef DEMO_USE_SNMP_VERSION_3
/* Use SNMPv3 to talk to the experimental server */
/* set the SNMP version number */
session.version=SNMP_VERSION_3;
/* set the SNMPv3 user name */
session.securityName = strdup("MD5User");
session.securityNameLen = strlen(session.securityName);
/* set the security level to authenticated, but not encrypted */
session.securityLevel = SNMP_SEC_LEVEL_AUTHNOPRIV;
/* set the authentication method to MD5 */
session.securityAuthProto = usmHMACMD5AuthProtocol;
session.securityAuthProtoLen = sizeof(usmHMACMD5AuthProtocol)/sizeof(oid);
session.securityAuthKeyLen = USM_AUTH_KU_LEN;
/* set the authentication key to a MD5 hashed version of our
passphrase "The Net-SNMP Demo Password" (which must be at least 8
characters long) */
if (generate_Ku(session.securityAuthProto,
session.securityAuthProtoLen,
(u_char *) our_v3_passphrase, strlen(our_v3_passphrase),
session.securityAuthKey,
&session.securityAuthKeyLen) != SNMPERR_SUCCESS) {
snmp_perror(argv[0]);
snmp_log(LOG_ERR,
"Error generating Ku from authentication pass phrase. \n");
exit(1);
}
#else /* we'll use the insecure (but simplier) SNMPv1 */
/* set the SNMP version number */
session.version = SNMP_VERSION_1;
/* set the SNMPv1 community name used for authentication */
session.community = "demopublic";
session.community_len = strlen(session.community);
#endif /* SNMPv1 */
/*
* Open the session
*/
SOCK_STARTUP;
ss = snmp_open(&session); /* establish the session */
if (!ss) {
snmp_sess_perror("ack", &session);
SOCK_CLEANUP;
exit(1);
}
/*
* Create the PDU for the data for our request.
* 1) We're going to GET the system.sysDescr.0 node.
*/
pdu = snmp_pdu_create(SNMP_MSG_GET);
anOID_len = MAX_OID_LEN;
if (!snmp_parse_oid(".1.3.6.1.2.1.1.1.0", anOID, &anOID_len)) {
snmp_perror(".1.3.6.1.2.1.1.1.0");
SOCK_CLEANUP;
exit(1);
}
#if OTHER_METHODS
/*
* These are alternatives to the 'snmp_parse_oid' call above,
* e.g. specifying the OID by name rather than numerically.
*/
read_objid(".1.3.6.1.2.1.1.1.0", anOID, &anOID_len);
get_node("sysDescr.0", anOID, &anOID_len);
read_objid("system.sysDescr.0", anOID, &anOID_len);
#endif
snmp_add_null_var(pdu, anOID, anOID_len);
/*
* Send the Request out.
*/
status = snmp_synch_response(ss, pdu, &response);
/*
* Process the response.
*/
if (status == STAT_SUCCESS && response->errstat == SNMP_ERR_NOERROR) {
/*
* SUCCESS: Print the result variables
*/
for(vars = response->variables; vars; vars = vars->next_variable)
print_variable(vars->name, vars->name_length, vars);
/* manipuate the information ourselves */
for(vars = response->variables; vars; vars = vars->next_variable) {
if (vars->type == ASN_OCTET_STR) {
char *sp = (char *)malloc(1 + vars->val_len);
memcpy(sp, vars->val.string, vars->val_len);
sp[vars->val_len] = '\0';
printf("value #%d is a string: %s\n", count++, sp);
free(sp);
}
else
printf("value #%d is NOT a string! Ack!\n", count++);
}
} else {
/*
* FAILURE: print what went wrong!
*/
if (status == STAT_SUCCESS)
fprintf(stderr, "Error in packet\nReason: %s\n",
snmp_errstring(response->errstat));
else if (status == STAT_TIMEOUT)
fprintf(stderr, "Timeout: No response from %s.\n",
session.peername);
else
snmp_sess_perror("snmpdemoapp", ss);
}
/*
* Clean up:
* 1) free the response.
* 2) close the session.
*/
if (response)
snmp_free_pdu(response);
snmp_close(ss);
SOCK_CLEANUP;
return (0);
} /* main() */
Compile command as following:
[happy@localhost 3]$ make snmpdemoapp
gcc -I.
net-snmp-config --cflags -c -o snmpdemoapp.o snmpdemoapp.c gcc -o snmpdemoapp snmpdemoapp.o
net-snmp-config --libsExecute command as following:
[happy@localhost 3]$ ./snmpdemoapp
SNMPv2-MIB::sysDescr.0 = STRING: test.net-snmp.org
value #1 is a string: test.net-snmp.org
Reference:
