Re: How do I find out the list of active network objects?

[Patrick Caulfield <patrick@pandh.demon.co.uk>]

On Tue, Feb 01, 2000 at 02:15:52PM +0000, Steve Whitehouse wrote:
> > 
> > Hi Reinhard,
> > 
> > Thanks ... that looks like it would be probably what I was looking for,
> > if only the file looked like that in Linux 2.3.39 ... I have:
> > 
> > Local                             Remote
> >  1.2/2189 0001:0001 0000:0000 2  1.5/0000 0000:0000 0000:0000 2  CI 
> > IMMED
> >  0.0/2188 0001:0001 0000:0000 2  0.0/0000 0000:0000 0000:0000 2 
> > OPENIMMED
> 
> Yes, the above line is the listening socket. Listening sockets are in the
> open state, as are all sockets after socket() has been called to create
> them and before connect() has been called.
> 
> The fields in this listening are divided into 3 section, Local, Remote
> and the last two entries being state (from DECnet specs) and the immediate
> of deferred acceptance flag.
> 
> The Local and Remote sections are divided as follows:
> 
> DECnetAddress/PortNumber NextDataSeqNum:NextOtherDataSeqNum 
>                                      NextAckNum:NextOtherDataAckNum flowsw
> 
> Sockets have local port numbers assigned upon bind() (Yes, you are right
> listening sockets don't need them, but its simpler to do it this way).
> You might not have actually called bind() itself though, because it is
> implict in some other commands.
> 
> Remote ports of course are set upon connect, so all sockets which are not
> yet connected will have zero remote ports. If its the local socket doing the
> connecting, you'll see a filled in remote address, but the port won't be
> assigned until connection is made. (e.g. the top line in your file here)
> 
> The other fields are more or less for debugging only. The flowsw field
> can take the following values:
> 
> 2 = Can send data
> 1 = Cannot send data
> 
> The value 0 is used in some DECnet messages meaning "no change" to the
> send/don't send status.
> 
> The Local DataSeqNum and OtherDataSeqNum fields are the numbers which will be
> placed into the next outgoing data/other data messages respectively. 
> The Local Ack fields contain the last Ack sent for data/other data to
> the remote host.
> 
> The Remote DataSeqNum and OtherDataSeqNum fields are the last message
> numbers heard from the remote host. The Remote Ack fields are the last
> received Ack numbers from the remote host.
> 
> If you want to find out more details about the connection, and get at things
> such as connect/disconnect data, then you'll need to use the set/getsockopt()
> functions. With them you should be able to set/get any/all of the connect
> and disconnect data and access control fields in the messages.
> 
> I did consider putting the socket addresses to which sockets were bound in
> the /proc/net/decnet files. I deceided in the end that it was possibly
> a security risk, to allow people to read things this way.
> 
> Its probably not a good idea to write programs to parse the data from the
> /proc/net/decnet file directly. Its format will change and I consider that
> the main purpose of it is to provide debugging information at the moment.
> 
> Certainly when we start to support flow control with methods other than
> the flowsw switch, I'm intending to add some more fields to allow debuging
> of that.
> 
> Sorry this message turned out so long - I hope it answers your questions.
> I put the rest of the explanation in since the formst of the file is
> rather cryptic and probably needs some explanation :-)
> 

That file could do with formalising at some stage so someone can write a
"netstat" type program for DECnet. As you can see there is a demand!

Patrick
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