SQL Server Performance Forum – Threads Archive
Port 1434
I have an analytical application that uses ADO to access sql server 2000. My client is getting multiple denials (see below) on their firewall on port 1434 from the same users but the sql server that they are connecting to is not a named instance. <br /><br />Why else would port 1434 be used?<br /><br />Deny udp src outside<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.92/1803 dst CssMachRm<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.102/1434<br />Deny udp src outside<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.92/1809 dst CssMachRm<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.102/1434<br />Deny udp src outside<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.92/1813 dst CssMachRm<img src=’/community/emoticons/emotion-12.gif’ alt=’:x’ />xx.xx.xx.102/1434<br /><br />Thanks<br /><br />Daniel Reber<br /><br /><br />When a client makes a connection dbnetlib.dll will try to open a connection to port 1434. The SQL 2000 server that always listen on this port will respond with a list of instances available, which ports they listen on and the network protocols that can be used to communicate. It then finds the first common protocol and use that. 1434 is not needed for things to work. If it’s blocked it works as with SQL 7.0 and you can always connect to the default instance. If you want to use a different SQL port or network library (tcp/ip, named pipes etc) you can always specify them in your connection string. Not sure if a request will be sent on 1434 if you specify full connection details in your connection string. Try specifying instance name, port (even if it is 1433) and network library and check if it still show up in the logs.
Thanks for the insight, that was helpful. Is there a protocol that is faster than the others? Thanks Dan Reber
You most likely will never notice any performance difference. There are other considerations in server/application/database/index design etc that will have much more impact than the choice of network library. It’s more a question of functions and in what environment they work (internet, local lan etc). TCP/IP is probably the most common. Check:
http://www.databasejournal.com/features/mssql/article.php/3334851
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