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From: Karthik Balaguru on 19 Feb 2010 14:16
Hi,
While looking for some valid port configurations,
i came across that in Solaris 2.2 by default the
ephemeral ports for TCP and UDP start at 32768.
Just eager to know the reason of why does it
start at 32768 (2 to the power of 15) ?
And i wonder why does it not follow the IANA range ?

Interestingly, many linux kernels also use the
same and why do not they stick towards IANA range ?

BSD and Windows stick towards 1024 to 4999
and 1025 to 5000 respectively, while Vista and
FreeBSD stick towards IANA range !

Any ideas ?

Thx in advans,
Karthik Balaguru
From: Andrew Gabriel on 21 Feb 2010 04:30
In article <f7c30ddb-5f3e-4cc2-8419-bebec2c14799(a)g28g2000prb.googlegroups.com>,
Karthik Balaguru <karthikbalaguru79(a)gmail.com> writes:
> Hi,
> While looking for some valid port configurations,
> i came across that in Solaris 2.2 by default the
> ephemeral ports for TCP and UDP start at 32768.
> Just eager to know the reason of why does it
> start at 32768 (2 to the power of 15) ?
> And i wonder why does it not follow the IANA range ?
>
> Interestingly, many linux kernels also use the
> same and why do not they stick towards IANA range ?
>
> BSD and Windows stick towards 1024 to 4999
> and 1025 to 5000 respectively, while Vista and
> FreeBSD stick towards IANA range !
>
> Any ideas ?

Solaris systems are often used for servers with hundreds of thousands
of network connections. Hence it is also often used for testing these
servers supporting a million or so network connections. By doubling
the number of ephemeral ports available, you can create twice as many
connections from a testing system to the server per IP address.
Solaris allows the tcp_smallest_anon_port (and tcp_largest_anon_port)
to be changed whilst system is running, and on testing systems, the
tcp_smallest_anon_port is sometimes lowered to make even more anon/
ephemeral ports available. Same can be done for UDP.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
From: David Schwartz on 21 Feb 2010 04:58
On Feb 19, 11:16 am, Karthik Balaguru <karthikbalagur...(a)gmail.com>
wrote:
> Hi,
> While looking for some valid port configurations,
> i came across that in Solaris 2.2 by default the
> ephemeral ports for TCP and UDP start at 32768.
> Just eager to know the reason of why does it
> start at 32768 (2 to the power of 15) ?
> And i wonder why does it not follow the IANA range ?

Two reasons. First, there aren't enough low ports in cases where
applications make large numbers of outgoing TCP connections like web
crawlers do. Second, there tend to be a lot of quasi-reserved ports
below 32,768 (such as 6666, 7000, 8000, 8080, and many others) and it
could cause some inconvenience if these ports were used accidentally.

DS
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