Add the --stats-every option. See http://seclists.org/nmap-dev/2009/q1/0404.html.

CHANGELOG

@@ -1,5 +1,10 @@
 # Nmap Changelog ($Id$); -*-text-*-
 
+o The new --stats-every option takes a time interval that controls how
+  often timing status updates are printed. It's intended to be used
+  when Nmap is run by another program as a subprocess. Thanks to
+  Aleksandar Petrinic for the initial implementation. [David]
+
 o [Ncat] The syntax accepted by the --allow, --deny, --allowfile, and
   --denyfile options is now the same as Nmap's target specifications.
   Additionally any errors in the allow or deny specifications are

NmapOps.cc

@@ -222,6 +222,7 @@ void NmapOps::Initialize() {
   verbose = 0;
   min_packet_send_rate = 0.0; /* Unset. */
   max_packet_send_rate = 0.0; /* Unset. */
+  stats_interval = 0.0; /* Unset. */
   randomize_hosts = 0;
   sendpref = PACKET_SEND_NOPREF;
   spoofsource = 0;

NmapOps.h

@@ -184,6 +184,8 @@ class NmapOps {
   float min_packet_send_rate;
   /* The requested maximum packet sending rate, or 0.0 if unset. */
   float max_packet_send_rate;
+  /* The requested auto stats printing interval, or 0.0 if unset. */
+  float stats_interval;
   int randomize_hosts;
   int spoofsource; /* -S used */
   int fastscan;

docs/refguide.xml

@@ -3402,6 +3402,23 @@ even if this option is not specified.
 </listitem>
 </varlistentry>
 
+      <varlistentry>
+        <term>
+          <option>--stats-every <replaceable>time</replaceable></option> (Print periodic timing stats)
+          <indexterm><primary><option>--stats-every</option></primary></indexterm>
+        </term>
+        <listitem>
+          <para>
+          Periodically prints a timing status message after each
+          interval of <replaceable>time</replaceable>. The time is a
+          specification of the kind described in
+          <xref linkend="man-performance"/>; so for example, use
+          <command>--stats-every 10s</command> to get a status update
+          every 10 seconds. Updates are printed to interactive output
+          (the screen) and XML output.
+          </para>
+        </listitem>
+      </varlistentry>
 
       <varlistentry>
         <term>

nmap.cc

@@ -674,6 +674,8 @@ int nmap_main(int argc, char *argv[]) {
       {"min-rate", required_argument, 0, 0},
       {"max_rate", required_argument, 0, 0},
       {"max-rate", required_argument, 0, 0},
+      {"stats_every", required_argument, 0, 0},
+      {"stats-every", required_argument, 0, 0},
       {0, 0, 0, 0}
     };
 
@@ -937,6 +939,10 @@ int nmap_main(int argc, char *argv[]) {
       } else if(optcmp(long_options[option_index].name, "max-rate") == 0) {
         if (sscanf(optarg, "%f", &o.max_packet_send_rate) != 1 || o.max_packet_send_rate <= 0.0)
           fatal("Argument to --max-rate must be a positive floating-point number");
+      } else if(optcmp(long_options[option_index].name, "stats-every") == 0) {
+	l = tval2msecs(optarg);
+	if (l < 0) fatal("Argument to --stats-every cannot be negative.");
+        o.stats_interval = (double) l / 1000.0;
       } else {
 	fatal("Unknown long option (%s) given@#!$#$", long_options[option_index].name);
       }

nmap_tty.cc

@@ -116,6 +116,7 @@
 #include <stdlib.h>
 
 #include "nmap_tty.h"
+#include "utils.h"
 #include "NmapOps.h"
 
 extern NmapOps o;
@@ -240,6 +241,8 @@ void tty_init()
    print a status message */
 bool keyWasPressed()
 {
+  /* Where we keep the automatic stats printing schedule. */
+  static struct timeval stats_time = { 0 };
   int c;
 
   if (o.noninteractive)
@@ -282,5 +285,30 @@ bool keyWasPressed()
        return true;
     }
   }
+
+  /* Check if we need to print a status update according to the --stats-every
+     option. */
+  if (o.stats_interval != 0.0) {
+    struct timeval now;
+
+    gettimeofday(&now, NULL);
+    if (stats_time.tv_sec == 0) {
+      /* Initialize the scheduled stats time. */
+      stats_time = *o.getStartTime();
+      TIMEVAL_ADD(stats_time, stats_time, (time_t) (o.stats_interval * 1000000));
+    }
+
+    if (TIMEVAL_AFTER(now, stats_time)) {
+      /* Advance to the next print time. */
+      TIMEVAL_ADD(stats_time, stats_time, (time_t) (o.stats_interval * 1000000));
+      /* If it's still in the past, catch it up to the present. */
+      if (TIMEVAL_AFTER(now, stats_time))
+        stats_time = now;
+      printStatusMessage();
+      /* Instruct the caller to print status too. */
+      return true;
+    }
+  }
+
   return false;
 }