connection refused – checklist for the new oracle dba career





below is list of checks a new oracle dba can perform when he is troubleshooting the server connection refused error message.

Routing, name server, server that "should" be up isn’t?

First aid check list for "connection refused":

– Check host name in connect string.
– Check port number in connect string.
– Try numeric IP address of server host in connect string, in case name server is hosed.
– Are there any firewalls between client and server blocking the port.
– Check that the db server is running.
– Check that the db server is listening to the port. On the server, try: "telnet localhost the-port-number". Or "netstat -an", there should be a listening entry for the port. You need to configure the database to accept TCP connections; read the documentation or google.
– Try "telnet server-host-name the-port-number" from the client, to see if firewalls are blocking it.
– If "telnet" fails: try telnet with the numeric ip address.
– If "telnet" fails: does it fail immediately or after an obvious timeout? How long is the timeout?
– Does the server respond to "ping serverhost" or "telnet serverhost" or "ssh serverhost"?

Author: admin