maximum simultaneous network connections

Hello Everybody...

I have a rare question, how much simoultaneous connections can linux
have, i know that linux has 655535 available ports, so i think 655535
connections at the same time, but, what if i have 10 network
interfaces.. do i have 655.350 possible concurrent connections?

Thanks in advance,
Mr. Boy
mrboy77-at-gmail.com

Mr. Boy wrote:

> Hello Everybody...
>
> I have a rare question, how much simoultaneous connections can linux
> have, i know that linux has 655535 available ports, so i think 655535
> connections at the same time, but, what if i have 10 network
> interfaces.. do i have 655.350 possible concurrent connections?

Generally, a TCP server (for example Apache HTTP server) only uses ONE port for
all incoming TCP connections. Each TCP connection requires memory for buffers
and a file handle, so you are only limited by memory and the max number of open
file handles.

> Thanks in advance,
> Mr. Boy
> mrboy77-at-gmail.com
>

--
Phil Frisbie, Jr.
Hawk Software
http://www.hawksoft.com

Phil Frisbie, Jr. <(E-Mail Removed)> wrote:
> Mr. Boy wrote:
>> I have a rare question, how much simoultaneous connections can
>> linux have, i know that linux has 655535 available ports, so i
>> think 655535 connections at the same time, but, what if i have 10
>> network interfaces.. do i have 655.350 possible concurrent
>> connections?

I presume you meant 65535 based on the port number being 16 bits?

> Generally, a TCP server (for example Apache HTTP server) only uses
> ONE port for all incoming TCP connections. Each TCP connection
> requires memory for buffers and a file handle, so you are only
> limited by memory and the max number of open file handles.

Yep. And that tends to be much lower than the theoretical limit based
on the number of remote IP addresses and 65535 ports per remote IP
address

I would probably include CPU overhead in the limitations, but perhaps
second order.

rick jones
--
Wisdom Teeth are impacted, people are affected by the effects of events.
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to raj in cup.hp.com but NOT BOTH...

>> I have a rare question, how much simoultaneous connections can
>> linux have, i know that linux has 655535 available ports, so i
>> think 655535 connections at the same time, but, what if i have 10
>> network interfaces.. do i have 655.350 possible concurrent
>> connections?

I think It's also related with the processes, like spawning child
processes which can handle the concurrent connections. That also
required the memory usage and max number of open files.


--
Raqueeb Hassan
Bangladesh

Rick Jones wrote:
> Yep. And that tends to be much lower than the theoretical limit based
> on the number of remote IP addresses and 65535 ports per remote IP
> address

That's obviusly not correct. You can have as much connections
as your system can support. Think about Apache, it uses only port 80
and can handle lots of connections at a time.

> rick jones

Regards.

--

Jose Maria Lopez Hernandez
Director Tecnico de bgSEC
(E-Mail Removed)
bgSEC Seguridad y Consultoria de Sistemas Informaticos
http://www.bgsec.com
ESPAÑA

The only people for me are the mad ones -- the ones who are mad to live,
mad to talk, mad to be saved, desirous of everything at the same time,
the ones who never yawn or say a commonplace thing, but burn, burn, burn
like fabulous yellow Roman candles.
-- Jack Kerouac, "On the Road"

Well guys, thanks to all for the quick response...

But i still have this doubt, you all are right about system resources,
and also reserved ports for services like http, pop, dns, etc... but
does the port limit number is directly related to the interfaces or to
the whole system !!!

Thanks Again!
Mr. Boy

Mr. Boy wrote:
> Well guys, thanks to all for the quick response...
>
> But i still have this doubt, you all are right about system resources,
> and also reserved ports for services like http, pop, dns, etc... but
> does the port limit number is directly related to the interfaces or to
> the whole system !!!

None of them. Services are bound to IPs, and an interface can have
multiples IPs, primary and secondary (aliases). So you can have 6
apache servers running in port 80 of 6 differents IPs with just
one interface and one system.

> Thanks Again!
> Mr. Boy

Regards.

--

Jose Maria Lopez Hernandez
Director Tecnico de bgSEC
(E-Mail Removed)
bgSEC Seguridad y Consultoria de Sistemas Informaticos
http://www.bgsec.com
ESPAÑA

The only people for me are the mad ones -- the ones who are mad to live,
mad to talk, mad to be saved, desirous of everything at the same time,
the ones who never yawn or say a commonplace thing, but burn, burn, burn
like fabulous yellow Roman candles.
-- Jack Kerouac, "On the Road"

Jose Maria Lopez Hernandez wrote:

> Rick Jones wrote:
>
>> Yep. And that tends to be much lower than the theoretical limit based
>> on the number of remote IP addresses and 65535 ports per remote IP
>> address
>
> That's obviusly not correct. You can have as much connections
> as your system can support. Think about Apache, it uses only port 80
> and can handle lots of connections at a time.

Reread what Rick said again.....He said that the theoretical limit is the number
of remote IP addresses (2^32 minus the multicast and other reserved addresses)
times 65535 ports, which is just under 2^48, or 281,474,976,710,656 connections!!!


--
Phil Frisbie, Jr.
Hawk Software
http://www.hawksoft.com

Phil Frisbie, Jr. wrote:
> Jose Maria Lopez Hernandez wrote:
>
>> Rick Jones wrote:
>>
>>> Yep. And that tends to be much lower than the theoretical limit based
>>> on the number of remote IP addresses and 65535 ports per remote IP
>>> address
>>
>>
>> That's obviusly not correct. You can have as much connections
>> as your system can support. Think about Apache, it uses only port 80
>> and can handle lots of connections at a time.
>
>
> Reread what Rick said again.....He said that the theoretical limit is
> the number of remote IP addresses (2^32 minus the multicast and other
> reserved addresses) times 65535 ports, which is just under 2^48, or
> 281,474,976,710,656 connections!!!
>
>
Yes, so lets try it out. Everybody on the internet, connect to his
machine, lets see if it works.

Jose Maria Lopez Hernandez <(E-Mail Removed)> wrote:
> Rick Jones wrote:
>> Yep. And that tends to be much lower than the theoretical limit
>> based on the number of remote IP addresses and 65535 ports per
>> remote IP address

> That's obviusly not correct. You can have as much connections
> as your system can support. Think about Apache, it uses only port 80
> and can handle lots of connections at a time.

I was being too concise. Server binds to a fixed port on a machine
with a single IP address. That means the theoretical limit to the
number of connections would be the number of remaining IP addresses
multiplied by the number of ports per remote IP address (65535). If
we constrain ourselves to IPv4 addressing, that means in broad terms
(not accounting for multicast IPs and whatnot) (2^32-1)* 65535, or a
very large number.

rick jones
--
No need to believe in either side, or any side. There is no cause.
There's only yourself. The belief is in your own precision. - Jobert
these opinions are mine, all mine; HP might not want them anyway...
feel free to post, OR email to raj in cup.hp.com but NOT BOTH...