Reserving sockets

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Roedy Green - 21 Oct 2007 13:02 GMT

Is there a mechanism either in Java or in Windows to reserve a socket?

Is there a mechanism to find out if a socket is in use by some other
program?

If you are a programmer, how do you go about deciding what socket to
use for some non-standard protocol?

Is this just something you expect the user to configure?

It turns out JetBrains IntelliJ Idea and something else that I have
not yet determined are fighting over the same sockets in the 6944
range.

PS. what is the best PCI Ethernet card, fast, rock solid drivers for
Vista and Ubuntu?

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Roedy Green - 21 Oct 2007 13:33 GMT

On Sun, 21 Oct 2007 12:02:34 GMT, Roedy Green
<see_website@mindprod.com.invalid> wrote, quoted or indirectly quoted
someone who said :

>Is there a mechanism to find out if a socket is in use by some other
>program?

I found this tool for Windows:

REM find out who is using which TCP/IP sockets
netstat -o

rem you might get a result like this:
rem Proto Local Address Foreign Address State PID
rem TCP 192.168.0.101:49181 209.34.241.67:http ESTABLISHED
4908

Rem you can then get more information about what that PID means
TaskList /o

too see without wrap, see http://mindprod.com/jgloss/tcpip.html

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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RedGrittyBrick - 21 Oct 2007 14:36 GMT

> Is there a mechanism either in Java or in Windows to reserve a socket?

Without binding to it?

> Is there a mechanism to find out if a socket is in use by some other
> program?

You already know about netstat. Another tool is SysInternals TCPView.
The obvious way from Java is to attempt to bind to it.

> If you are a programmer, how do you go about deciding what socket to
> use for some non-standard protocol?

AIUI, a "socket" is the combination of a transport level protocol (e.g.
UDP or TCP), an IP-address and a port number. Therefore I'm assuming you
mean "how do I choose a TCP or UDP port number for my application?"

I'd read this, especially the first few paragraphs:
http://www.iana.org/assignments/port-numbers
It may also be interesting to grep it for "any private"?

If I was in a huge corporation planning a product I expected to become
very widely used (i.e. by millions of computers on the Internet) then I
suppose I'd try applying to IANA for a reserved port.

> Is this just something you expect the user to configure?

I'd have a carefully chosen default but allow the user to configure it.

> It turns out JetBrains IntelliJ Idea and something else that I have
> not yet determined are fighting over the same sockets in the 6944
> range.

IRC? Good luck!

> PS. what is the best PCI Ethernet card, fast, rock solid drivers for
> Vista and Ubuntu?

No idea, I'd pick a popular and well-known brand. E.g. Intel Gigabit.

I feel I have probably added nothing to your existing knowledge, sorry
about that :-)

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Roedy Green - 23 Oct 2007 08:34 GMT

On Sun, 21 Oct 2007 14:36:55 +0100, RedGrittyBrick
<RedGrittyBrick@SpamWeary.foo> wrote, quoted or indirectly quoted
someone who said :

>No idea, I'd pick a popular and well-known brand. E.g. Intel Gigabit.

that's what I got. Intel has a feature that appeals, a common driver
for all its models. That strikes me then as more likely the card will
be supported for a long time to come and the driver will be bug-free.

Now to see if it clears up the weird TCP/IP locking problems.

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Martin Gregorie - 21 Oct 2007 15:37 GMT

> Is there a mechanism either in Java or in Windows to reserve a socket?

I look at my /etc/services file, but then I run Linux. There's a
regularly updated list of port numbers at

http://www.iana.org/assignments/port-numbers

This replaces RFC 1700, which formerly contained the definitive list.

> Is there a mechanism to find out if a socket is in use by some other
> program?

netstat

It is available for *NIX systems and NT-based Windows systems, so it
should be available from Win 2K onwards. Use the -n option to see port
numbers: otherwise it shows the service name. Use -p to see the program
name and PID.

> If you are a programmer, how do you go about deciding what socket to
> use for some non-standard protocol?

I've noticed that the low 16000s are unused and tend to use those in
sequence so my servers don't clash.

> Is this just something you expect the user to configure?

I assign a default port but make the port number configurable, via a
configuration file, command line option or both. If both, the command
line option overrides the config file.

Many common programs, both open source and proprietary, are written with
a default and configurable override. This includes most database and web
servers. Its essential for these to have configurable ports because its
not uncommon to run multiple copies on a server. Their clients must also
use configurable port assignments.

> It turns out JetBrains IntelliJ Idea and something else that I have
> not yet determined are fighting over the same sockets in the 6944
> range.

According to the IANA database 6944 is unassigned, so imagine my
surprise. I hope their port assignments are configurable.

> PS. what is the best PCI Ethernet card, fast, rock solid drivers for
> Vista and Ubuntu?

I used to swear by 3COM and at Linksys. My only, seldom used,
Windows/Linux dual boot box has still got a 10 year old 3COM 10mb card
in it which has never given trouble.

This laptop has a D-Link DFE-670TXB PCMCIA card and my house server has
a RealTek RTL8139 installed. The D-Link and Realtek are both dual speed
10/100 devices and both have been trouble free for 2-3 years. My LAN is
based on a D-Link hub which has 'just run' for about 8 years.

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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

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Lew - 21 Oct 2007 16:15 GMT

Roedy Green wrote:

>> PS. what is the best PCI Ethernet card, fast, rock solid drivers for
>> Vista and Ubuntu?

> I used to swear by 3COM and at Linksys. My only, seldom used,
> Windows/Linux dual boot box has still got a 10 year old 3COM 10mb card
[quoted text clipped - 4 lines]
> 10/100 devices and both have been trouble free for 2-3 years. My LAN is
> based on a D-Link hub which has 'just run' for about 8 years.

Realtek makes the motherboard-embedded NIC on my machine, an AMD-64-based
machine. No worries, but then, I'm dual-booting Fedora Core 7 and Win XP, not
the OSes of Roedy's concern.

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Lew

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Martin Gregorie - 22 Oct 2007 13:52 GMT

> Roedy Green wrote:
>>> PS. what is the best PCI Ethernet card, fast, rock solid drivers for
[quoted text clipped - 12 lines]
> AMD-64-based machine. No worries, but then, I'm dual-booting Fedora
> Core 7 and Win XP, not the OSes of Roedy's concern.

My IBM Netvista (866 MHz, PIII) has a Realtek card in it which is
slightly surprising. I would have expected it to be on the motherboard.
It runs FC6 +J2SE 1.4 and will be upgraded to FC7 + JSE 6 when I get a
round tuit.

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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

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Lew - 22 Oct 2007 14:11 GMT

> My IBM Netvista (866 MHz, PIII) has a Realtek card in it which is
> slightly surprising. I would have expected it to be on the motherboard.
> It runs FC6 +J2SE 1.4 and will be upgraded to FC7 + JSE 6 when I get a
> round tuit.

I don't remember mobos with integrated NICs being very common, or even extant,
in P3 days. They started being more common only in the last couple or few years.

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Lew

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Martin Gregorie - 22 Oct 2007 19:45 GMT

>> My IBM Netvista (866 MHz, PIII) has a Realtek card in it which is
>> slightly surprising. I would have expected it to be on the
[quoted text clipped - 4 lines]
> extant, in P3 days. They started being more common only in the last
> couple or few years.

Its an ATX mobo and had I assumed that integrated NICs came in with the
ATX format. Shows how long it is since I bought a new system: the last
new one I bought has a baby-AT board.

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martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

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Christopher Benson-Manica - 22 Oct 2007 15:15 GMT

>> It turns out JetBrains IntelliJ Idea and something else that I have
>> not yet determined are fighting over the same sockets in the 6944
>> range.
>
> According to the IANA database 6944 is unassigned, so imagine my
> surprise. I hope their port assignments are configurable.

According to the in-house IntelliJ guru, it's possible that IntelliJ
is using 6944 for its licensing enforcement, which might be why it
isn't documented anywhere. It also sounds like it's not configurable,
unfortunately.

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C. Benson Manica | I appreciate all corrections, polite or otherwise.
cbmanica(at)gmail.com |
----------------------| I do not currently read any posts posted through
sdf.lonestar.org | Google groups, due to rampant unchecked spam.

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Christopher Benson-Manica - 22 Oct 2007 16:06 GMT

> Is there a mechanism either in Java or in Windows to reserve a socket?

ITYM "port".

> Is this just something you expect the user to configure?

That's been my general strategy, but I don't write the type of
application where that might be a real concern.

> It turns out JetBrains IntelliJ Idea and something else that I have
> not yet determined are fighting over the same sockets in the 6944
> range.

As a data point, Intellij 7 on this XP box seems not to be interested
in that port.

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Roedy Green - 23 Oct 2007 20:28 GMT

On Sun, 21 Oct 2007 12:02:34 GMT, Roedy Green
<see_website@mindprod.com.invalid> wrote, quoted or indirectly quoted
someone who said :

>It turns out JetBrains IntelliJ Idea and something else that I have
>not yet determined are fighting over the same sockets in the 6944
>range.

I did a clean reinstall of Windows Vista and the problem has gone
away. An update install did not help.

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Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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