At 02:51 PM 9/13/01, Tony van Ree wrote:
>Hi,
>
>Here is what I found at
>
>http://perlfect.com/articles/sockets.shtml
>
>Perl, Sockets and TCP/IP Networking.
>
>An oversimplified introduction to sockets
>
>Sockets are a mechanism that allows programs to communicate, either on the
>same machine or across a network. The way it works is
>pretty simple: Each machine on a network is identified by some address. In
>this tutorial we will talk about tcp/ip networking, so by
>network address we mean an IP address. (like 192.168.4.4) Apart from the
>IP address that specifies a machine, each machine has a
>number of ports that allow handling multiple connections simultaneously.
>
>A program that wishes to receive a connection from another program, asks
>the operating system to create a socket and bind it to some
>port. Then the program sits and listens on the socket it has created to
>receive incoming connections. The other program also creates a
>socket for communicating witht he receiver. The caller needs to specify
>the IP address and the port number of the receiving end.
Ah hah. Now that makes sense! ;-) And that's how AppleTalk sockets work
too, which explains why the AppleTalk specification uses that term. Of
course, AppleTalk also uses "socket" for the field in the packet that
identifies the next layer up, which TCP and UDP would call a port.
Thanks to everyone who responded!
Priscilla
>If all
>goes well, and as we will see shortly, the two programs establish a
>communication through the network using their sockets. The two
>programs may exchange information, each by writing to and reading from the
>socket it has created.
>
>++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
>Just to add a bit to all of this
>
>Teunis
>Hobart, Tasmania
>Australia
>
>
>On Wednesday, September 12, 2001 at 09:53:44 PM, Priscilla Oppenheimer
wrote:
>
> > Ports are used by TCP and UDP to identify the next layer up in the
packet.
> >
> > IP has a Protocol field that has a similar function.
> >
> > Ethernet II has EtherType. IEEE 802.3 has the 802.2 Service Access Point
> > (SAP). IPX and AppleTalk have sockets.
> >
> > Almost every protocol has some way of specifying what the next layer up
> is.
> > The recipient uses it to pass the data to the right process. The sender
> > also uses it to identify itself.
> >
> > Socket has another meaning in the Unix world which I have never quite
> > understood. Perhaps someone else can explain that.
> >
> > Priscilla
> >
> > At 08:25 PM 9/12/01, Dennis Laganiere wrote:
> > >Hopefully this will start a new conversation. I've tried to describe
the
> > >difference between Ports and Sockets. Your thoughts are welcome...
> > >
> > >Port Numbers are used by IP to pass information to the upper layers;
they
> > >provide the mechanism for cooperating applications to communicate.
Numbers
> > >below 1024 are well known ports, and above 1024 are dynamically assigned
> > >ports. You will usually find registered ports are for vendor specific
> > >applications in the range above 1024.
> > >
> > >Here are some common IP Ports:
> > >20/21 FTP
> > >23 Telnet
> > >25 SMTP
> > >37 Time Service
> > >49 TACACS
> > >53 DNS
> > >67 BootP Server
> > >68 BootP Client
> > >69 TFTP
> > >110 POP3
> > >161 SNMP
> > >
> > >IPX sockets are part of the IPX stack, and are used much like port
numbers
> > >in IP; they direct data encapsulation in the IPX Header to the
appropriate
> > >upper layer protocols. There are well-known ones, others that are
> assigned
> > >to proprietary applications, and a series of numbers used randomly by
> > >clients, just like in IP. Also like IP ports, they identify the process
on
> > >the server or client that needs to get the data in the packet.
> > >
> > > Here are some common IPX sockets:
> > > 0x451 NCP
> > > 0x452 SAP
> > > 0x453 RIP
> > > 0x455 NetBios
> > > 0x456 Diagnostic
> > > 0x457 Serialization
> > > 0x85be IPX EIGRP
> > > 0x9001 NLSP
> > > 0x9004 IPXWAN
> > > 0x9086 IPX Ping
> > >
> > >
> > >The AppleTalk protocol suite also uses sockets. Socket numbers 1-127
are
> > >statically assigned (RTMP uses 1, ZIP uses 6, etc).
> > ________________________
> >
> > Priscilla Oppenheimer
> > http://www.priscilla.com
>--
>www.tasmail.com
________________________
Priscilla Oppenheimer
http://www.priscilla.com
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