If this is a freebie or developers edition, it only allows local connections originating from the same host. The express edition, I think does like 25 total connections
Actually that's not true at all. The freedie (developper or express) versions can be accessed from remote hosts just as any other Sybase servers.
The issue that the OP has is that the database server is listening on the loopback address (127.0.0.1). This happens when the hostname is listed in /etc/hosts along with the loopback (the default configuration on Red Hat systems) and /etc/hosts is read first when doing a hostname lookup.
The it gets tricky, unless the hostname actually maps to the dynamic IP address.
I guess you could do some scripting at startup to pull the ip address via /sbin/ifconfig and update the Sybase interfaces file, and then start the db server. But you would still have the problem of the client machine that needs to know where to connect to (i.e. what IP address the server has today...)