Updated the documentation to include some information on port support

Documentation/sshuttle.md

@@ -36,7 +36,12 @@ entire subnet to the VPN.
     single IP address), 1.2.3.4/32 (equivalent to 1.2.3.4),
     1.2.3.0/24 (a 24-bit subnet, ie. with a 255.255.255.0
     netmask), and 0/0 ('just route everything through the
-    VPN').
+    VPN'). In addition, it is also possible to filter
+    additionally on the tcp port to include/exclude.
+    This is done by adding :port at the end of your netmask.
+    Note that `:port` is also valid. In this case, the netmask
+    will be defaulted to 0/0. Valid examples are `:80`,
+    `0:80`, `1.2.3.4:80` and `1.2.3.4/24:80`.
 
 -l, --listen=*[ip:]port*
 :   use this ip address and port number as the transparent

main.py

@@ -65,7 +65,7 @@ def parse_ipport(s):
 dns        capture local DNS requests and forward to the remote DNS server
 python=    path to python interpreter on the remote server
 r,remote=  ssh hostname (and optional username) of remote sshuttle server
-x,exclude= exclude this subnet (can be used more than once)
+x,exclude= exclude this subnet and/or port (can be used more than once)
 exclude-from=  exclude the subnets in a file (whitespace separated)
 v,verbose  increase debug message verbosity
 e,ssh-cmd= the command to use to connect to the remote [ssh]