Hiding instances on the n/w (Port 1434)

12 May 2005 9:32 AM

Pmcg

Hi,
I tried to hide an instance of MSSQL2000 SP3 on the n/w by first removing
all the enabled protocols using the server network utility which worked fine,
i then renabled the TCP/IP protocol and selected hide server which seemed to
switch the port number to 2433, which i understand has an implication for
clients regarding connection strings including port numbers, aliasing etc.
I then switched the port number back to 1433 and de-selected the hide server
option but now i can connect to the machine using query analyzer when i know
the machine name but if i try to hit the button which lists all servers on
the n/w the server does not appear. I believe this list is populated based on
a n/w port scan which builds the list based on machines that respond to a
request on UDP port 1434.

If anyone knows why the server will not appear i would appreciate a pointer,
i have also attempted to find help about blocking on port 1434 but cannot
find help on how to do so, keep getting instructions on blocking at the
firewall, i just want to understand how this works.

Thanks in advance
Pat

12 May 2005 3:46 PM

Mark Allison

Pmcg,

You cannot prevent SQL Server listening on port 1434. If you want to prevent
clients accessing this port, you have no choice but to use a firewall.

SQL Server's enumeration mechanism can only list servers that are registered
in Enterprise Manager, and ones that are on your subnet - the broadcast does
not work across routers or firewalls. Perhaps this is the problem.

--
Mark Allison, SQL Server MVP
http://www.markallison.co.uk

Looking for a SQL Server replication book?
http://www.nwsu.com/0974973602m.html

Show quote

"Pmcg" wrote:

> Hi,
> I tried to hide an instance of MSSQL2000 SP3 on the n/w by first removing
> all the enabled protocols using the server network utility which worked fine,
> i then renabled the TCP/IP protocol and selected hide server which seemed to
> switch the port number to 2433, which i understand has an implication for
> clients regarding connection strings including port numbers, aliasing etc.
> I then switched the port number back to 1433 and de-selected the hide server
> option but now i can connect to the machine using query analyzer when i know
> the machine name but if i try to hit the button which lists all servers on
> the n/w the server does not appear. I believe this list is populated based on
> a n/w port scan which builds the list based on machines that respond to a
> request on UDP port 1434.
>
> If anyone knows why the server will not appear i would appreciate a pointer,
> i have also attempted to find help about blocking on port 1434 but cannot
> find help on how to do so, keep getting instructions on blocking at the
> firewall, i just want to understand how this works.
>
>
> Thanks in advance
> Pat