New option '-M' to set the 'Don't Fragment' flag (#91, Don Bowman)

ChangeLog

@@ -1,7 +1,8 @@
 UNRELEASED
+  * (feature) Ignore network and broadcast for cidrs /31 and /32 (#102, Martin Topholm)
+  * (feature) New option '-M' to set the "Don't Fragment" flag (#91, Don Bowman) 
   * (bugfix) Exit code should be 2 when the hostname can't be resolved
             (fixes #98, reported by @green-fox)
-  * (feature) Ignore network and broadcast for cidrs /31 and /32 (#102, Martin Topholm)
   * (bugfix)  Fix issue compliling on RHEL/Centos 7 (#95, @jbackman)
 
 2015-10-21  David Schweikert  <david@schweikert.ch>

ci/test-02-help.pl

@@ -27,6 +27,7 @@ Usage: fping [options] [targets...]
    -i n       interval between sending ping packets (in millisec) (default 25)
 ${I_HELP}   -l         loop sending pings forever
    -m         ping multiple interfaces on target host
+   -M         set the Don't Fragment flag
    -n         show targets by name (-d is equivalent)
    -O n       set the type of service (tos) flag on the ICMP packets
    -p n       interval between ping packets to one target (in millisec)

doc/fping.pod

@@ -197,6 +197,10 @@ Print B<fping> version information.
 
 Set the IP TTL field (time to live hops). 
 
+=item B<-M>
+
+Set the "Don't Fragment" bit in the IP header (used to determine/test the MTU).
+
 =back
 
 =head1 EXAMPLES

src/fping.c

@@ -2395,7 +2395,7 @@ void usage(int is_error)
 #endif
     fprintf(out, "   -l         loop sending pings forever\n" );
     fprintf(out, "   -m         ping multiple interfaces on target host\n" );
-    fprintf(out, "   -M         Don't Fragment (IP_PMTUDISC_DO)\n" );
+    fprintf(out, "   -M         set the Don't Fragment flag\n" );
     fprintf(out, "   -n         show targets by name (-d is equivalent)\n" );
     fprintf(out, "   -O n       set the type of service (tos) flag on the ICMP packets\n" );
     fprintf(out, "   -p n       interval between ping packets to one target (in millisec)\n" );