I have to run at the same time on the same windows host, 2 instances of stunnel : a client instance and a server instance I have 2 config files : stunnel-client.conf , stunnel-server.conf Each configuration works, but not at the same time. I can install 2 services (with differents service name), but i can't start both services at the same time. I have to stop the first one to start the second one stunnel.exe -install stunnel-client.conf stunnel.exe -install stunnel-server.conf stunnel.exe -start stunnel-client.conf stunnel.exe -start stunnel-server.conf --> error 1053 stunnel.exe -stop stunnel-client.conf stunnel.exe -start stunnel-server.conf stunnel.exe -start stunnel-client.conf --> error 1053 It is also not possible to start the both configurations directly (no service mode). test run with stunnel 4.42b2 on windows XPe and Win2008R2 -- Laurent LICOUR