I shelled out for SSHDroid Pro and am quite disappointed that it can't be configured to allow connections over the Wifi Hotspot interface without also allowing connections from the mobile data interface (i.e. the open Internet). Is there another SSH server app that can do this and is otherwise relatively feature-complete?
I use Servers Ultimate Pro to limit my server's (SSH/FTP/WebDAV) accessibility to Wifi hotspot's subnet (I use it on wlan0 or rndis0). The server cannot be mapped from internet in this way. Its very easy to use, even a newbie can setup a server on it.
About Servers Ultimate Pro
★★Run over 60 servers with over 70 protocols!★★
Now you can run a CVS, DC Hub, DHCP, UPnP, DNS, DDNS, eDonkey, Email (POP3 / SMTP), FTP Proxy, FTP, FTPS, FTPES, Flash Policy, Git, Gopher, HTTP Snoop, ICAP, IRC Bot, IRC, ISCSI, Icecast, LPD, Load Balancer, MQTT, Memcached, MongoDB, MySQL, NFS, NTP, NZB Client, Napster, PHP, Lighttpd, PXE, Port Forwarder, RTMP, Remote Control, Rsync, SIP, SMB/CIFS, SMPP, SMS, Socks, SFTP, SSH, Server Monitor, Styx, Syslog, TFTP, Telnet, Time, Torrent Client, Torrent Tracker, Trigger, Unison, UPnP Port Mapper, VNC, VPN, Wake On Lan, Web, WebDAV, WebSocket, X11 and/or XMPP server!
Start a server easily on the 'Simple' tab or go advanced and add users, allowed IP's, start/stop rules and more! Multiple servers can be run at the same time! No root needed
SSHelper provides a standard openssh server in a mini linux environment. I can specify which network interfaces to allow ssh access on by connecting via ssh and editing the configuration file at
/data/data/com.arachnoid.sshelper/etc/sshd_config. The change to make is pretty straightforward. If you don't know how to use
vi you might have some issues making the change, but I guess you could edit it on a computer over
sshfs or by copying the file back and forth or what have you.
As an added bonus, this app solved my problem with not being able to connect to my phone from my Mac using
sshfs. The solution (or workaround) is to use openssh as the ssh server rather than Dropbear, and SSHelper is one of the few apps for Android that does this.