[rc5] RC5 for Mac--which settings?

Rebecca and Rowland rebecca at astrid.u-net.com
Sat Jul 19 02:06:41 EDT 1997


>Sorry to add to the growing list of Mac users who are (justly)
>complaining about the lack of
>support, but I can't figure out what Network Settings to use. I seem to
>be getting by with
>the trial and error method, but I can't find a setting that consistently
>works. The "help"
>page didn't shed much light on the issue. As you can see,
>
>>    These options, in english are:

>>       1. I can communicate freely to the Internet on all ports.

>>       2. I can communicate freely on telnet ports

>>       3. I can communicate freely on telnet ports, but need uuencoding

>>       4. I have a local HTTP proxy that I can go through

>>       5. Let me specify my own things (expert mode)

>I have a serial port, but what the blazes is a telnet port? Or a normal
>port? Or a standard port? Or a port filter?

The ports referred to above aren't hardware ports like a serial port -
they're a software thing.

As Steve Langasek explained to me (and I've just pasted it here because it
seems that more people than me need to know about it).  Perhaps someone
might consider including this information in the documentation?

As you may or may not know, the packets (bundles) that are used to
transmit information across the Internet are themselves tagged with
several pieces of information which tell the network how to handle the
packet.  It tells, first of all, the destination in the form of an IP
address, which tells the network in what direction to send it; it tells
the protocol, providing instructions for unwrapping the packet once it
arrives there; and it specifies the port.  The term 'port' is a
convention, of course; what in computerspeke isn't? :)  But it is
analagous to the way a computer can have multiple peripherals, each
attached to its own port on the back of the system.  The virtual software
ports used in Internet transactions are what let the tcp/ip software on
your end separate the email packets from the news packets, or the web
packets; they're also what lets a computer be both a web server and an ftp
server, for instance.  Although the port number doesn't tell what kind of
information is inside the packet, it does tell which program is
responsible for the packet, a task which is made easier by the assignment
of standard port numbers to common applications.  Telnet, for example,
runs on port 23; mail is sent out on port 25.  Bovine has been chosen to
run on port 2056.  There are 65536 available ports in all, on any system;
normally only the first 1024 ports, the so-called "reserved" ports, are
used for listening (serving), for reasons which are tied to user
permissions in unix.  These are the same ports which are sometimes
screened out by firewalls for security reasons, especially in a corporate
setting.  Sometimes, machines behind firewalls can only talk to the
outside world by going through the telnet port on a gateway machine;
sometimes they have to go through the http port.  The bovine clients are
designed to work with these standard types of firewalls.

In the case of an ISP, very rarely are any ports blocked.  You can confirm
this by using any telnet program that lets you specify a remote port (if I
remember correctly, NCSA telnet does) and telnetting to
rc5proxy.distributed.net on port 2056.  If you get a connection (though
probably not any intelligible information), then you know the client can
do the same.
>
>As far as I know, I have no firewall, draconian or otherwise, and I'm
>not sure how http
>tunneling or proxies could be relevant to my situation.
>
>I'm just a normal guy with a mac and a modem who wants to participate in
>this thing. Can
>someone please contact me, off-list if necessary, and walk me through
>this procedure in
>*real* english?
>

The easiest thing to do is give the client your email address and let it
run - if it contacts the server, fetches blocks, checks them, and sends
them back, then everything's working okay.  If you're not sure that it's
working okay, have a look at the log file and see if it claims that the
client's doing all of those things - if it doesn't you've got problems.

I'm a bit in the dark myself, because the v2 client's not working properly
on my Mac, so anything I tell you from my own experience is of doubtful use.

Hope this helps
Rowland.


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