The bug is located in shellinabox/service.c Removing the flags:
-oRhostsRSAAuthentication=no -oRhostsRSAAuthentication=no and recompiling solves this issue.
- Bug#873019: shellinabox: ssh unsupported option ... Leonardo Marino-Ramirez
- Bug#873019: Located the bug in shellinabox/... Leonardo Mariño-Ramírez
