Apple - Which options exist for SSH tunneling clients on iOS?

iSSH supported opening tunnels. For example, I can set a tunnel on local port 4444 that points to an IP address and port 80. Opening localhost:4444 in Safari then loads that website through the tunnel. iSSH also has good support for saved configurations and public key authentication.

Under the App Store rules, iSSH is only allowed to keep the connection open for up to 10 minutes in the background, so after 9 minutes or so I'll get a notification and the tunnel will be closed if I don't switch back to iSSH quickly enough.

As of 2015, iSSH isn't available anymore. The same functionality likely exists in other iOS SSH clients, but I haven't tried any myself.

If you are looking for an application to setup local port forwarding like:

ssh -f -L 3000:talk.google.com:5222 home -N

You could check SSHTunnel, it allows you to easily manage and precisely control your ssh tunnels. Can create and share SOCKS5 proxy (aka Dynamic Port Forwarding) or setup a Local Port Forwarding.

Also, you can manually specify the local port to bind, configure connection timeout, see logs and statistics etc.

vSSH supports tunneling. You can setup tunneling in the "Port forwarding" section of the connection settings. Local, remote and dynamic (SOCKS proxy) forwarding are supported.

You are able to use tunneling even without opening SSH session (shell permissions are not necessary for ssh user in this case).

Due to iOS limitation the app can work in background only for 10 minutes (iOS 5,6) or 3 minutes (iOS 7). vSSH reminds you about this timeout through Notifications.