siebns file cannot and MUST NOT be modified by hand using any text editor as it is CRC checked by an Oracle algorithm, e.g. vi, and what used to happen is that you should send the file to Oracle Support and they’ll clean it up for you, but this is only supported for versions earlier than Siebel 8, and so you should follow the following easy steps in case the siebns.dat file is messed up (many unused enterprises in my case):

1. Make sure that you shutdown the Siebel Server
2. DO NOT shutdown the Gateway server, it must be up to correctly modify the siebns.dat
3. Navigate to /$SIEBEL_ROOT/gtwysrvr and run cfgenv.sh to prepare some environment variables (. ./cfgenv.sh)
4. Navigate to /$SIEBEL_ROOT/gtwysrvr/bin and run ./ssincfgw to start the Gateway configuration
5. Choose “Remove Existing Configuration” and then “Remove an Enterprise From an existing gateway server”
6. Type the name of the enterprise you want to remove (unluckily there is no list to choose from, so you have to know them, and if you don’t, you can open the siebns.dat file using a text editor such as vi, you’ll find all your enterprises there, DON’T MODIFY ANYTHING BY HAND!)
7. Execution Successfull 🙂
8. Restart your Gateway and Siebel Server.

That’s my first Siebel 8 subject and it’s pretty strange for a first post I guess, hope it’s useful 🙂