Re: Connect via odbc from Windows to Linux

Bruce Hyatt wrote:
> I am trying to set up an odbc connection from Windows 2000 to Postgresql running on Linux (CentOS 4.7).
>
> I have the appropriate Postgresql jdbc driver on the windows box as well as the hosts file with the linux host. Postgresql.conf has listen_addresses = '*'. The port is the same on both ends.
>
> Trying various configurations with the odbc datasource administrator, the most friendly response I can get from a test is that the connected party/host failed to respond ("properly after a period of time" in the case of the 'party').
>
> I do have portsentry running on the linux host but the windows box is not blocked.
>
> I'm afraid there must be a simple solution but I can't figure out what it is. Where should I look?
>

the postgres JDBC driver doesn't use ODBC at all. its a native Java
driver that speaks the Postgres protocol directly.

to use ODBC, you'd need the Windows ODBC Postgres stack, which is fairly
complex to get working right and has little to do with Postgres JDBC,
and would just serve to confuse things.

In your Java app, you specify jdbc:postgresql://host/database as the
connection string... I'd probably run tcpdump on hte linux side,
`tcpdump -n tcp port 5432` then try and connect, this will show you if
the windows/java app is attemping to connect and its packets are getting
through... ideally you should see a whole >SYN <ACK >... tcp
connection handshake.

it /should/ look something like...

20:56:01.930328 IP 10.0.0.100.34307 > 10.0.0.10.postgres: S
3335832814:3335832814(0) win 32792 <mss 16396,sackOK,timestamp 671638094
0,nop,wscale 7>
20:56:01.930393 IP 10.0.0.10.postgres > 10.0.0.100.34307: S
3338209742:3338209742(0) ack 3335832815 win 32768 <mss
16396,sackOK,timestamp 671638094 671638094,nop,wscale 7>
20:56:01.930439 IP 10.0.0.100.34307 > 10.0.0.10.postgres: . ack 1 win
257 <nop,nop,timestamp 671638094 671638094>
20:56:01.930556 IP 10.0.0.100.34307 > 10.0.0.100.postgres: P 1:9(8) ack
1 win 257 <nop,nop,timestamp 671638094 671638094
...... (many more packets should follow)

where 10.0.0.100 is the Windows PC's IP, 10.0.0.10 is the Postgres
server's IP, and 34307 is a random 'source' port (this can be almost
anything. if you're using a different port than 5432, then 'postgres'
would be replaced with this other port (and, of course, you should
specify this port on the tcpdump command instead of 5432...)

so... if you DO see this, the network is working and its some other
problem. if you don't see it, its a network problem. or the JDBC
client isn't specifying the host correctly, or somehting like that.