doc: refine document for argument `-b`, fix #2353

README.md

@@ -408,6 +408,13 @@ you may refer to the man pages of the applications, respectively.
                                   (not available in redir mode)
 
        [-b <local_address>]       Local address to bind.
+                                  For servers: Specify the local address to use 
+                                  while this server is making outbound 
+                                  connections to remote servers on behalf of the
+                                  clients.
+                                  For clients: Specify the local address to use 
+                                  while this client is making outbound 
+                                  connections to the server.
 
        [-u]                       Enable UDP relay.
                                   (TPROXY is required in redir mode)

doc/shadowsocks-libev.asciidoc

@@ -101,9 +101,15 @@ multi-interface environment.
 Not available in redir mode.
 
 -b <local_address>::
-Specify local address to bind.
+Specify the local address to bind.
 +
-Not available in server nor manager mode.
+For servers: Specify the local address to use while this server is making 
+outbound connections to remote servers on behalf of the clients.
++
+For clients: Specify the local address to use while this client is making 
+outbound connections to the server.
++
+Not available in manager mode.
 
 -u::
 Enable UDP relay.

doc/ss-local.asciidoc

@@ -93,7 +93,8 @@ That results the traffic go out through eth1, but not lo nor eth0.
 This option is useful to control traffic in multi-interface environment.
 
 -b <local_address>::
-Specify local address to bind.
+Specify the local address to use while this client is making outbound 
+connections to the server.
 
 -u::
 Enable UDP relay.

doc/ss-redir.asciidoc

@@ -83,7 +83,8 @@ Specify max number of open files.
 Only available on Linux.
 
 -b <local_address>::
-Specify local address to bind.
+Specify the local address to use while this client is making outbound 
+connections to the server.
 
 -u::
 Enable UDP relay.

doc/ss-server.asciidoc

@@ -88,7 +88,8 @@ That results the traffic go out through eth1, but not lo nor eth0.
 This option is useful to control traffic in multi-interface environment.
 
 -b <local_address>::
-Specify local address to bind.
+Specify the local address to use while this server is making outbound 
+connections to remote servers on behalf of the clients.
 
 -u::
 Enable UDP relay.

doc/ss-tunnel.asciidoc

@@ -92,7 +92,8 @@ That results the traffic go out through eth1, but not lo nor eth0.
 This option is useful to control traffic in multi-interface environment.
 
 -b <local_address>::
-Specify local address to bind.
+Specify the local address to use while this client is making outbound 
+connections to the server.
 
 -u::
 Enable UDP relay.