From: Jakub Jirutka <jakub@jirutka.cz>
Date: Mon, 28 Aug 2017 21:13:00 +0200
Subject: [PATCH] Add option "stay in foreground"

This patch is based on https://support.nagios.com/forum/viewtopic.php?f=34&t=17597.

--- a/src/nrpe.c
+++ b/src/nrpe.c
@@ -98,6 +98,7 @@
 int     use_inetd=TRUE;
 int     debug=FALSE;
 int     use_src=FALSE; /* Define parameter for SRC option */
+int     stay_in_foreground=FALSE;
 
 
 void complete_SSL_shutdown( SSL *);
@@ -171,6 +172,7 @@
 		printf("   -d          =    Run as a standalone daemon\n");
 		/* Updates help section to indicate how to start under SRC on AIX */
 		printf("   -d -s       =    Run as a subsystem under AIX\n");        
+		printf("   -f          =    Run and stay in foreground\n");
 		printf("\n");
 		printf("Notes:\n");
 		printf("This program is designed to process requests from the check_nrpe\n");
@@ -292,6 +294,22 @@
 		handle_connection(0);
 	        }
 
+	/* if we're running in the foreground... */
+	else if (stay_in_foreground==TRUE){
+
+		/* drop privileges */
+		drop_privileges(nrpe_user,nrpe_group);
+
+		/* make sure we're not root */
+		check_privileges();
+
+		/* log info to syslog facility */
+		syslog(LOG_NOTICE,"Starting up NRPE");
+
+		/* wait for connections */
+		wait_for_connections();
+		}
+
 	/* if we're running under SRC... 
 	   we don't fork but does drop-privileges*/
 	else if (use_src==TRUE){
@@ -2088,6 +2103,7 @@
 		{"4", no_argument, 0, '4'},
 		{"6", no_argument, 0, '4'},
 		{"daemon", no_argument, 0, 'd'},
+		{"foreground", no_argument, 0, 'f'},
 		{"no-ssl", no_argument, 0, 'n'},
 		{"help", no_argument, 0, 'h'},
 		{"license", no_argument, 0, 'l'},
@@ -2099,7 +2115,7 @@
 	if(argc<2)
 		return ERROR;
 
-	snprintf(optchars,MAX_INPUT_BUFFER,"c:hVldi46n");
+	snprintf(optchars,MAX_INPUT_BUFFER,"c:hVldi46nf");
 
 	while(1){
 #ifdef HAVE_GETOPT_LONG
@@ -2130,6 +2146,11 @@
 		case 'd':
 			use_inetd=FALSE;
 			have_mode=TRUE;
+			break;
+		case 'f':
+			stay_in_foreground=TRUE;
+			use_inetd=FALSE;
+			have_mode=TRUE;
 			break;
 		case 'i':
 			use_inetd=TRUE;