diff --git a/doc/debian_build_doc.md b/doc/debian_build_doc.md
index 27792b2ce..fbfe721fb 100644
--- a/doc/debian_build_doc.md
+++ b/doc/debian_build_doc.md
@@ -98,10 +98,21 @@ REGISTRAR_CODE="test"
 SECONDS=60
 # Max connections per IP
 BLOCKCOUNT=100
+# Source specification. Address can be either a network name, a hostname, a network IP address 
+# (with /mask), or a plain IP address. Hostnames will be resolved once only, before the rule
+# is submitted to the kernel. Please note that specifying any name to be resolved with 
+# a remote query such as DNS is a really bad idea.  The mask can be either a network mask or 
+# a plain number, specifying the number of 1's at the left side of the network mask. 
+# Thus, a mask of 24 is equivalent to 255.255.255.0. A "!" argument before 
+# the address specification inverts the sense of the address. 
+# The flag --src is an alias for this option. Multiple addresses can be specified, 
+# but this will expand to multiple rules (when adding with -A), 
+# or will cause multiple rules to be deleted (with -D). 
+REGISTRAR_HANDLE_SOURCE = 'x.x.x.x'
 # default action can be DROP or REJECT or something else.
 DACTION="REJECT"
 $IPT -A INPUT -p tcp --dport 700 -i eth0 -m state --state NEW -m recent --set
-$IPT -A INPUT -p tcp --dport 700 -m recent --name $REGISTRAR_CODE --rdest --rcheck --hitcount ${BLOCKCOUNT} --seconds ${SECONDS} -j ${DACTION}
+$IPT -A INPUT -p tcp --dport 700 -s $REGISTRAR_HANDLE_SOURCE -m recent --name $REGISTRAR_CODE --rdest --rcheck --hitcount ${BLOCKCOUNT} --seconds ${SECONDS} -j ${DACTION}
 ````
 
 After adding iptable counters, please add correct permissions to proc files at path /proc/net/xt_recent