compare the tnsnames.ora on the win box with that on the linux box and make necessary changes (see in bold below) in the later.

TST.WORLD =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = sun101)(PORT = 1521))
)
(CONNECT_DATA =
(SERVICE_NAME = tst)
)
)
Check the docs for more info...Configuring the Local Naming Method

http://download-west.oracle.com/docs...gcf.htm#448222

HTH.