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Re: tnsping succeeds, client connect does not, error 12545

From: Paul Drake <paled_at_home.com>
Date: Sat, 18 Aug 2001 20:03:49 GMT
Message-ID: <3B7ECA11.E8D69AD@home.com>


wayne wrote:
>
> Hi List,
> Got Oracle 8.1.6 running on Solaris 7 with W2k clients.
> When the Clients (this is a clarify client not sqlplus) try to
> connect, an ORA-12545 Connect failed because target host or object
> does not exist.
> tnsping succeeds, as do client connects from clients on a different
> subnet, and the IP address, rather than name, of the server is
> specified in tnsnames.ora.
>
> So maybe it's the firewall? Does anyone know what is required at the
> network level for successfull Oracle client-server operation?
> Also, if some of these network facilities are missing, due to firewall
> problemettes, could that lead to an error 12545?
>
> Tia
>
> Wayne

Wayne,

tnsping sends packets only to the listener port, hence, a reply would most likely be allowed by the firewall. a client connection to an oracle instance (dedicated server) requires the use of non-privileged ports in the range 1025-65536.

There is a wealth of information w.r.t this up on Metalink.

You're going to have to mention the firewall (which you may not want to do) if you want specific info.

The simplest way to get this to work is to simply have the firewall route the traffic - meaning - exposed the listener on a public IP address - and have the firewall limit incoming requests by ip address. This removes the problems assocatied with masquerading and Network Address Translation.
It also means that the server is susceptible to a large number of attacks.

A more difficult way is to use shared servers with a fixed ip address for the dispatchers.

Another more difficult means is to use Oracle's Connection Manager (CMAN). The packets sent via Net8 have the source and destination IP addresses embedded - hence NAT without a proxy fails to establish connections. Connection Manager is a method via which NAT can be supported.

start here:
http://otn.oracle.com/docs/products/oracle8i/doc_library/817_doc/network.817/a76933/glossary.htm#433789

hth,

Paul Received on Sat Aug 18 2001 - 15:03:49 CDT

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