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diff --git a/src/main.rs b/src/main.rs
index 9eb0da7..33afc76 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -13,7 +13,10 @@ use std::sync::mpsc::channel;
 use std::thread;
 use std::time::Duration;
 use clap::{ Arg, App };
+use rust_util::util_msg::{ is_logger_level_enabled, MessageType };
+use rust_util::util_net::IpAddressMaskGroup;
 
+const LOCAL_ADDR: &str = "127.0.0.1";
 const TIMEOUT: u64 = 3 * 60 * 100; //3 minutes
 
 fn main() {
@@ -33,34 +36,48 @@ fn main() {
         .arg(Arg::with_name("allowed_list").short("A").long("allowed-list").takes_value(true).multiple(true).help("Allowed IP list, e.g. 127.0.0.1, 120.0.0.0/8"))
         .get_matches();
 
-    let local_port: i32 = matches.value_of("local_port").unwrap().parse().unwrap();
-    let remote_port: i32 = matches.value_of("remote_port").unwrap().parse().unwrap();
+    let local_port: u16 = matches.value_of("local_port").unwrap().parse().unwrap();
+    let remote_port: u16 = matches.value_of("remote_port").unwrap().parse().unwrap();
     let remote_host = matches.value_of("host").unwrap();
     let bind_addr = match matches.value_of("bind") {
         Some(addr) => addr.to_owned(),
-        None => "127.0.0.1".to_owned(),
+        None => LOCAL_ADDR.to_owned(),
     };
+    let allowed_ip_address_mask_list = IpAddressMaskGroup::parse(
+        &matches.values_of("allowed_list")
+                .map(|l| l.map(|i| i.to_owned()).collect::<Vec<_>>())
+                .unwrap_or_else(|| vec![])
+    );
+    debugging!("Allowed ip address mask list count: {}", allowed_ip_address_mask_list.ip_address_mask_group.len());
+    if is_logger_level_enabled(MessageType::DEBUG) {
+        allowed_ip_address_mask_list.ip_address_mask_group.iter().for_each(|ip| {
+            debugging!("- {}", ip);
+        });
+    }
 
-    forward(&bind_addr, local_port, &remote_host, remote_port);
+    forward(&bind_addr, local_port, &remote_host, remote_port, &allowed_ip_address_mask_list);
 }
 
-fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32) {
+fn forward(bind_addr: &str, local_port: u16, remote_host: &str, remote_port: u16, allowed_ip_address_mask_list: &IpAddressMaskGroup) {
     let local_addr = format!("{}:{}", bind_addr, local_port);
+    debugging!("Listen address and port: {}", local_addr);
     let local = UdpSocket::bind(&local_addr).unwrap_or_else(|_| panic!("Unable to bind to {}", &local_addr));
     information!("Listening on {}", local.local_addr().unwrap());
 
     let remote_addr = format!("{}:{}", remote_host, remote_port);
 
-    let responder = local.try_clone()
-        .unwrap_or_else(|_| panic!("Failed to clone primary listening address socket {}", local.local_addr().unwrap()));
+    let responder = local.try_clone().unwrap_or_else(
+        |_| panic!("Failed to clone primary listening address socket {}", local.local_addr().unwrap())
+    );
     let (main_sender, main_receiver) = channel::<(_, Vec<u8>)>();
     thread::spawn(move || {
         debugging!("Started new thread to deal out responses to clients");
         loop {
             let (dest, buf) = main_receiver.recv().unwrap();
             let to_send = buf.as_slice();
-            responder.send_to(to_send, dest)
-                .unwrap_or_else(|_| panic!("Failed to forward response from upstream server to client {}", dest));
+            responder.send_to(to_send, dest).unwrap_or_else(
+                |_| panic!("Failed to forward response from upstream server to client {}", dest)
+            );
         }
     });
 
@@ -68,7 +85,10 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
     let mut buf = [0; 64 * 1024];
     loop {
         let (num_bytes, src_addr) = local.recv_from(&mut buf).expect("Didn't receive data");
-        // TODO check src_addr ...
+        if !allowed_ip_address_mask_list.is_empty_or_matches(&src_addr) {
+            information!("Banned source address: {}", src_addr);
+            continue;
+        }
 
         //we create a new thread for each unique client
         let mut remove_existing = false;
@@ -79,7 +99,7 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
             let client_id = format!("{}", src_addr);
 
             if remove_existing {
-                debugging!("Removing existing forwarder from map.");
+                debugging!("Removing existing forwarder from map: {}", client_id);
                 client_map.remove(&client_id);
             }
 
@@ -96,12 +116,14 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
                     //connection to 0.0.0.0 in all cases.
                     let temp_outgoing_addr = format!("0.0.0.0:{}", 1024 + rand::random::<u16>());
                     debugging!("Establishing new forwarder for client {} on {}", src_addr, &temp_outgoing_addr);
-                    let upstream_send = UdpSocket::bind(&temp_outgoing_addr)
-                        .unwrap_or_else(|_| panic!("Failed to bind to transient address {}", &temp_outgoing_addr));
-                    let upstream_recv = upstream_send.try_clone()
-                        .unwrap_or_else(|_| panic!("Failed to clone client-specific connection to upstream!"));
+                    let upstream_send = UdpSocket::bind(&temp_outgoing_addr).unwrap_or_else(
+                        |_| panic!("Failed to bind to transient address {}", &temp_outgoing_addr)
+                    );
+                    let upstream_recv = upstream_send.try_clone().unwrap_or_else(
+                        |_| panic!("Failed to clone client-specific connection to upstream!")
+                    );
 
-                    let mut timeouts : u64 = 0;
+                    let mut timeouts: u64 = 0;
                     let timed_out = Arc::new(AtomicBool::new(false));
 
                     let local_timed_out = timed_out.clone();
@@ -112,15 +134,14 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
                             match upstream_recv.recv_from(&mut from_upstream) {
                                 Ok((bytes_rcvd, _)) => {
                                     let to_send = from_upstream[..bytes_rcvd].to_vec();
-                                    local_send_queue.send((src_addr, to_send))
-                                        .expect("Failed to queue response from upstream server for forwarding!");
+                                    local_send_queue.send((src_addr, to_send)).expect("Failed to queue response from upstream server for forwarding!");
                                 },
                                 Err(_) => {
                                     if local_timed_out.load(Ordering::Relaxed) {
                                         debugging!("Terminating forwarder thread for client {} due to timeout", src_addr);
                                         break;
                                     }
-                                }
+                                },
                             };
                         }
                     });
@@ -128,8 +149,9 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
                     loop {
                         match receiver.recv_timeout(Duration::from_millis(TIMEOUT)) {
                             Ok(from_client) =>  {
-                                upstream_send.send_to(from_client.as_slice(), &remote_addr_copy)
-                                    .unwrap_or_else(|_| panic!("Failed to forward packet from client {} to upstream server!", src_addr));
+                                upstream_send.send_to(from_client.as_slice(), &remote_addr_copy).unwrap_or_else(
+                                    |_| panic!("Failed to forward packet from client {} to upstream server!", src_addr)
+                                );
                                 timeouts = 0; //reset timeout count
                             },
                             Err(_) => {
@@ -139,7 +161,7 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
                                     timed_out.store(true, Ordering::Relaxed);
                                     break;
                                 }
-                            }
+                            },
                         };
                     }
                 });
@@ -157,7 +179,7 @@ fn forward(bind_addr: &str, local_port: i32, remote_host: &str, remote_port: i32
                     debugging!("New connection received from previously timed-out client {}", client_id);
                     remove_existing = true;
                     continue;
-                }
+                },
             }
         }
     }