# cd usr/sbin/
# ls
IGMPProxy  brctl      dhcp-fwd   dropbear   ggsip      lightbox   pppd       routed     tftpu      thttpd     udhcpc     udhcpd     updatedd   upnpd
# dropbear --help
Unknown argument --help
Dropbear v
Usage: dropbear [options]
Options are:
-b bannerfile     Display the contents of bannerfile before user login
                  (default: none)
-d dsskeyfile     Use dsskeyfile for the dss host key
                  (default: /etc/dropbear/dropbear_dss_host_key)
-r rsakeyfile     Use rsakeyfile for the rsa host key
                  (default: /etc/dropbear/dropbear_rsa_host_key)
-F                Don't fork into background
-E                Log to stderr rather than syslog
-w                Disallow root logins
-p port           Listen on specified tcp port, up to 10 can be specified
                  (default 22 if none specified)