The message "INIT: Command is respawning too rapidly. Will try again in 5 minutes." means that the init process has started your command, but the command has exited almost immediately, so init had to restart it. This cycle has repeated a few times, so init concludes further restart attempts are not likely to be helpful just now. It stops trying for 5 minutes, to prevent a configuration mistake from consuming all the available CPU time.
You have redirected the error messages of your command to /dev/null, so there is no information about what is wrong.
Change the ">/dev/null 2>&1" part of the command to ">>/tmp/port_forward.log 2>&1" or something similar.
Then execute "init -q" to make init try again a few times, then read the file (/tmp/port_forward.log or whatever name you used).
As a matter of personal preference: I would not embed a complex command like that directly to /etc/inittab.
I would make it a small two-line script (the first line would be "#!/bin/sh", the second your command). After making the script executable and testing that it works, I might add an inittab entry to _execute that script_.
A wild guess about the cause of the error:
maybe the su command is returning an error because of strange quoting?
You have:
...su - eigsec "-c /usr/bin/ssh ...
Try this instead:
...su - eigsec -c "/usr/bin/ssh ...
MK
MK
