InterClient/InterServer 1.1x for InterBase 4.0 Linux does not exist.
InterClient is an all Java JDBC compliant driver for InterBase. Currently, there is
no InterClient/InterServer with InterBase 4.0 Linux. The Linux version of InterServer
is available with the InterBase 5.6 Linux product, which is not a free download like the
InterBase 4.0 for Linux. InterBase 5.6 Linux includes InterClient 1.5, which can be
used to interact with InterBase 4.x and 5.x databases.
As you probably seen, InterClient 1.5 for Linux is available on our website, but this
version must be used with InterBase 5.x Linux. So, if you want to use InterClient
with InterBase on Linux, you'll either need to run InterServer on a different platform,
upgrade to InterBase 5.6 Linux, or wait for the InterBase 6.0 release.