More don't:s for nyetworking.

p4raw-id: //depot/perl@20669

diff --git a/pod/perlport.pod b/pod/perlport.pod
index 73a6616..c6f0c4a 100644 (file)
--- a/pod/perlport.pod
+++ b/pod/perlport.pod
@@ -494,13 +494,26 @@ Don't assume that you can reach the public Internet.
 Don't assume that there is only one way to get through firewalls
 to the public Internet.
 
+Don't assume that you can reach outside world through any other port
+than 80, or some web proxy.  ftp is blocked by many firewalls.
+
 Don't assume that you can reach yourself or any node by the name
-'localhost'.  The same goes for '127.0.0.1'.
+'localhost'.  The same goes for '127.0.0.1'.  You will have to try
+both.
+
+Don't assume that the host has only network card, or that it can't
+bind to many virtual IP addresses.
+
+Don't assume a particular network device name.
 
 Don't assume that any particular port (service) will respond.
 
 Don't assume that you can ping hosts and get replies.
 
+All the above "don't":s may look daunting, and they are -- but the key
+is to degrade gracefully if one cannot reach the particular network
+service one wants.  Croaking or hanging do not look very professional.
+
 =head2 Interprocess Communication (IPC)
 
 In general, don't directly access the system in code meant to be