Re: Text based synchronous communication tool for Linux?

From	cross@spitfire.i.gajendra.net (Dan Cross)
Newsgroups	comp.unix.programmer
Subject	Re: Text based synchronous communication tool for Linux?
Date	2024-12-09 17:11 +0000
Organization	PANIX Public Access Internet and UNIX, NYC
Message-ID	<vj78c8$pka$1@reader2.panix.com> (permalink)
References	<vj44hq$3q2ag$1@dont-email.me> <vj69hi$asvu$1@dont-email.me> <vj6p0h$j5l$1@reader2.panix.com> <vj7839$g95f$1@dont-email.me>

Show all headers | View raw

In article <vj7839$g95f$1@dont-email.me>,  <Muttley@DastardlyHQ.org> wrote:
>On Mon, 9 Dec 2024 12:49:21 -0000 (UTC)
>cross@spitfire.i.gajendra.net (Dan Cross) wibbled:
>>In article <vj69hi$asvu$1@dont-email.me>,  <Muttley@DastardlyHQ.org> wrote:
>>>On Sun, 8 Dec 2024 18:36:35 -0000 (UTC)
>>>cross@spitfire.i.gajendra.net (Dan Cross) wibbled:
>>>>works is brittle and doesn't work well over the modern Internet.
>>>>In particular, it is de-facto limited to IPv4 and doesn't
>>>>play well with firewalls: it involves sending the contents of a
>>>>`sockaddr_in` across the network, and using that to set up a
>>>>(direct) TCP connection between processes.  One could imagine
>>>
>>>Huh? I don't get how that works.
>>
>>Yes.
>>
>>>You need a connection in the first place to
>>>send anything unless you use a broadcast UDP address. You can't just 
>>>automagically set up a connection without the OS network layer playing its 
>>>part.
>>
>>A `sockaddr_in` is just a data structure that names a socket
>>address.  For the Internet family, it's just got a few things in
>>it: an address, a port number, a family type, and length.
>>That's basically it.
>>
>>The walk `talk` works, the client sets up a TCP listening
>>socket, and then sends the address for that to the `talk` daemon
>>both locally and at the distant end; the talk daemon at the
>>distant end then alerts the destired user that someone wants to
>>talk to them.
>>
>>Assuming that person wants to respond, _they_ invoke their
>>talk client, which talks to the local talk daemon, sees the
>>pending request, retrieves the socket address structure, and
>>uses it to connect to the originating user's talk client's
>>TCP listening socket.
>>
>>The connection to the talk daemon isn't connection oriented
>>at all; it's done via a UDP packet.  That is, the talk client
>>creates a listening TCP socket, takes the (binary) address
>>of the listening socket, embeds that address in a UDP packet,
>>sends that over the network, and on the distant end that
>>informatio is used to create a (TCP) connection back to the
>>origin.
>
>What an idiotically complicated way to set up a simple TCP connection.

It wasn't the best protocol, but the complexity of setting up
the connection was not why.

	- Dan C.

Back to comp.unix.programmer | Previous | Next — Previous in thread | Next in thread | Find similar

Thread

Text based synchronous communication tool for Linux? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-08 13:47 +0100
  Re: Text based synchronous communication tool for Linux? Richard Kettlewell <invalid@invalid.invalid> - 2024-12-08 13:14 +0000
    ytalk (Was: Text based synchronous communication tool for Linux?) gazelle@shell.xmission.com (Kenny McCormack) - 2024-12-08 17:18 +0000
    Re: Text based synchronous communication tool for Linux? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-09 16:32 +0100
  Re: Text based synchronous communication tool for Linux? John McCue <jmccue@whitedwf.jmcunx.com> - 2024-12-08 14:15 +0000
    Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-08 16:25 +0000
      Re: Text based synchronous communication tool for Linux? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-08 18:06 +0100
        Re: Text based synchronous communication tool for Linux? cross@spitfire.i.gajendra.net (Dan Cross) - 2024-12-08 18:36 +0000
          Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-09 08:25 +0000
            Re: Text based synchronous communication tool for Linux? cross@spitfire.i.gajendra.net (Dan Cross) - 2024-12-09 12:49 +0000
              Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-09 17:06 +0000
                Re: Text based synchronous communication tool for Linux? cross@spitfire.i.gajendra.net (Dan Cross) - 2024-12-09 17:11 +0000
                Re: Text based synchronous communication tool for Linux? Nicolas George <nicolas$george@salle-s.org> - 2024-12-09 17:56 +0000
        Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-09 08:23 +0000
          Re: Text based synchronous communication tool for Linux? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-09 09:37 +0100
            Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-09 09:11 +0000
              Re: Text based synchronous communication tool for Linux? gazelle@shell.xmission.com (Kenny McCormack) - 2024-12-09 14:27 +0000
              Re: Text based synchronous communication tool for Linux? Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-09 16:21 +0100
                Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-09 17:13 +0000
                Re: Text based synchronous communication tool for Linux? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-12-10 17:57 -0500
                [meta] Harry Potter, Physics, Tools, Perception, etc. (was Re: Text based synchronous communication tool for Linux?) Janis Papanagnou <janis_papanagnou+ng@hotmail.com> - 2024-12-11 03:04 +0100
                Re: [meta] Harry Potter, Physics, Tools, Perception, etc. (was Re: Text Muttley@DastardlyHQ.org - 2024-12-11 08:37 +0000
                Re: [meta] Harry Potter, Physics, Tools, Perception, etc. (was Re: Text based synchronous communication tool for Linux?) cross@spitfire.i.gajendra.net (Dan Cross) - 2024-12-12 00:55 +0000
                Re: [meta] Harry Potter, Physics, Tools, Perception, etc. (was Re: Text Muttley@DastardlyHQ.org - 2024-12-12 08:39 +0000
                Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-11 08:35 +0000
                Re: Text based synchronous communication tool for Linux? James Kuyper <jameskuyper@alumni.caltech.edu> - 2024-12-11 19:47 -0500
        Re: Text based synchronous communication tool for Linux? scott@slp53.sl.home (Scott Lurndal) - 2024-12-09 14:02 +0000
      Re: Text based synchronous communication tool for Linux? Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2024-12-09 13:45 +0000
        Re: Text based synchronous communication tool for Linux? gazelle@shell.xmission.com (Kenny McCormack) - 2024-12-09 14:23 +0000
        Re: Text based synchronous communication tool for Linux? Richard Kettlewell <invalid@invalid.invalid> - 2024-12-09 14:27 +0000
          Re: Text based synchronous communication tool for Linux? Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2024-12-09 15:02 +0000
        Re: Text based synchronous communication tool for Linux? Nicolas George <nicolas$george@salle-s.org> - 2024-12-09 15:23 +0000
          Re: Text based synchronous communication tool for Linux? Geoff Clare <geoff@clare.See-My-Signature.invalid> - 2024-12-11 13:36 +0000
        Re: Text based synchronous communication tool for Linux? vallor <vallor@cultnix.org> - 2024-12-09 19:30 +0000
          Re: Text based synchronous communication tool for Linux? Muttley@DastardlyHQ.org - 2024-12-10 08:36 +0000

csiph-web