I stumbled across some SuperMicro servers refusing to let me connect to their graphical console via IPMI web interface with the meaningless error message “Connection failed”.

So I found a way to do this manually:

Requirements:

• stunnel (tested version: 5.38)
• java (tested version: openjdk 1.8.0_121, IcedTea 3.3.0, Alpine 8.121.13-r0)
• iKVM.jar from ftp://ftp.supermicro.com/utility/IPMIView/Linux/IPMIView_2.12.0_build.160804_bundleJRE_Linux_x64.tar.gz
• some stunnel.conf with following content (replace with your target IP):

[HOST_iKVM]
client = yes
accept = 127.0.0.1:12345
connect = 172.16.XX.XX:3520

• start:

stunnel /path/to/your/stunnel.conf

• replace user, pass and target IP and start:

java -Djava.library.path=. -jar iKVM.jar 127.0.0.1 adminuser 'adminpass' null 12345 623 0 0 --BMCIP172.16.XX.XX''