Consultor Eletrônico

Status: Unverified

FACT(s) (Environment):

OpenEdge 10.x

SYMPTOM(s):

Delay when installing WebClient in a firewalled local network

A delay occurs when loading webclient.htm in a web browser

The installation control in webclient.htm takes a long time to load

Two minutes delay when installing WebClient

Installation proceeds normally after delay

Local network blocks connections to Internet hosts

Network packet analyzer shows attempts to connect to www.installengine.com

CAUSE:

The firewall does not report explicit connection refusals to WebClient installer when it attempts to connect to the site www.installengine.com.
When the WebClient installer is loaded, it will attempt to connect to www.installengine.com if an Internet connection seems to be available. If the local network advertises that the host is reachable (such as replying a valid IP address when the name www.installengine.com is queried by DNS) then the installation control will try to reach the host for two minutes before it abandons and continues with the installation.
In firewalled networks, usually the DNS would refuse to resolve external names into IP addresses, or the firewall would send explicit connection denials to the client application when it tries to connect outside the local network. In those cases, the WebClient installer would abandon immediately its attempt to connect to the outside host. When the firewall does not send connection denials, the WebClient installer cannot detect automatically that the connection is not possible and waits for two minutes before it bails out.

FIX:

Several workarounds are available:
- configure the firewall to return connection errors for unauthorized attempts
- add a special rule in the firewall to authorize connections to www.installengine.com
- configure the local DNS to refuse to resolve the name www.installengine.com
- configure the local DNS to return a local (invalid) address for the name www.installengine.com, such as 127.0.0.1