Connecting to remote database with VPN, running queries hang when more than 15 rows. (4251134)

User connects to remote network using VPN. The user tries to run a query in Toad but it hangs when trying to return more than 15 rows. This issue only happens on some databases. If the user goes into the Schema Browser and clicks on the table, then clicks on the data tab, Toad will also hang.

Running the same query in SQL Plus does not produce any issues. Connecting to an in house or local database does not have any issues in Toad.

Issue was found to be caused by VPN firewall. The setting Denial of service attack detection was turned on in the firewall. Turning this off Toad continued to work like normal.

Please contact your network administrators regarding the VPN. Check to see if there are any firewalls or antivirus systems that may be blocking Toad. See if Toad needs to be added to any kind of network permission. Check to see if there is any limit to what data or size of data that can be sent through the VPN. Also check with the your Oracle DBA to find if there are any Oracle settings limiting the connection.

Heres an excerpt from Doc ID 742535.1 from Metalink that may also explain the problem:

Note: If you cannot find a setting for SQL Inspection, please try looking for and disable "Support for Oracle SQL Net" (sonicwall firewall setting)

Problem was isolated to use of port 1521 over a VPN Tunnel that utilizes Cisco 5400/5500 Series
Adaptive Security Appliances (ASA) where the Cisco SQLnet fixup protocol/Sql Inspector was
enabled. However, on port 1522 where this Sql packet Inspection was not enabled, the problem did
not reproduce. Note: The Cisco 5400/5500 Series Adaptive Security Appliances (ASA) have this SQLnet fixup protocol/Sql Inspection enabled by default for port 1521.

If you are using a port other than 1521,disable SQL inspection.