From b1b66df37c0b05ba05d9636234bad0cc02a1bd03 Mon Sep 17 00:00:00 2001
From: Martin Sustrik <sustrik@fastmq.commkdir>
Date: Thu, 21 Jan 2010 12:07:42 +0100
Subject: PGM man page improved

---
 man/man7/zmq_pgm.7 | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/man/man7/zmq_pgm.7 b/man/man7/zmq_pgm.7
index fb37735..6d70a56 100644
--- a/man/man7/zmq_pgm.7
+++ b/man/man7/zmq_pgm.7
@@ -18,6 +18,14 @@ socket option.
 
 PGM transport can be used only with ZMQ_PUB and ZMQ_SUB sockets.
 
+Caution: PGM protocol runs directly on top of IP protocol and thus needs to
+open raw IP socket. On some operating systems this operation requires special
+privileges. On Linux, for example, you would need to either run your application
+as root or set adequate capabilities for your executable. Alternative approach
+is to use UDP transport,
+.IR zmq_udp(7) ,
+that stacks PGM on top of UDP and thus needs no special privileges.
+
 .SH CONNECTION STRING
 
 Connection string for PGM transport is "pgm://" followed by an IP address
-- 
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