From: NeilBrown <neilb@xxxxxxxx> Some people notice the extra privileged UDP port that rpcbind creates, and wonder what it is for. So add a section to the man page to explain it. Signed-off-by: NeilBrown <neilb@xxxxxxxx> --- man/rpcbind.8 | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/man/rpcbind.8 b/man/rpcbind.8 index fbf0ace24b27..6ba318f5ff77 100644 --- a/man/rpcbind.8 +++ b/man/rpcbind.8 @@ -66,6 +66,25 @@ reports the condition and terminates. The .Nm utility can only be started by the super-user. +.Sh "BROADCAST RPC" +.Nm +supports a little-used part of the ONC-RPC specification known as +Broadcast RPC. +A client can send a UDP broadcast message to +.Nm +on every host on a local subnetwork, and each +.Nm +will forward the request to the local service if available. +Should the service reply, +.Nm +will forward that reply back to the originator. +To support this, +.Nm +creates an extra UDP socket bound to an arbitrary privileged port +number, and uses it to forward requests to local services and to +receive replies from them. +When configuring a firewall, the "port 111" sockets may need to +be accessible through the firewall, but the extra UDP socket does not. .Sh OPTIONS .Bl -tag -width indent .It Fl a -- 2.43.0
