SSH port forwarding with automatic reconnect, script executing at startup

Question

In short, every time my computer boots, I would like to start a ssh port-forwarding connection that will reconnect with the server if the connection drops. Computer is Debian Wheezy x64.

An initial and successful connection can be made as follows:

screen -dmS autossh autossh -M 29000 -N -v -p 22 -l user -i /path/to/.ssh/id_rsa -L port:my-computer:port my-server.com

How can this be made to run at startup? (preferably by user, not root). Here is currently how I have been starting programs at boot:

rc.local calls my startup script as follows:

su -c "/home/username/scripts/startup" username

Currently, /home/username/scripts/startup contains the following:

screen -dmS program1 python my-python-program
screen -dmS program2 python my-python-program2
screen -dmS autossh autossh -M 29000 -N -v -p 22 -l user -i /path/to/.ssh/id_rsa -L port:my-computer:port my-server.com

Once booted, all three programs appear to be running (by list screen -ls). There is no problem with program1 or program 2. However, autossh is not actually forwarding the port.

The difference between a successful connection run by me, and an unsucessful connection run at startup is that a successful connection has the line:

debug1: channel 4: free: direct-tcpip: listening port 8082 for 192.168.1.104 port 80, connect from ::1 port 59681, 
nchannels 5

While the unsuccessful connection keeps trying like so:

debug1: Connection to port 8082 forwarding to 192.168.1.104 port 80 requested.
debug1: channel 4: new [direct-tcpip]
debug1: Connection to port 8082 forwarding to 192.168.1.104 port 80 requested.
debug1: channel 5: new [direct-tcpip]
debug1: Connection to port 8082 forwarding to 192.168.1.104 port 80 requested.
debug1: channel 6: new [direct-tcpip]
debug1: Connection to port 8082 forwarding to 192.168.1.104 port 80 requested.
debug1: channel 7: new [direct-tcpip]
debug1: Connection to port 8082 forwarding to 192.168.1.104 port 80 requested.
debug1: channel 8: new [direct-tcpip]

Any idea what is wrong? Why would a program work fine when I run it manually, but not inside my startup script?

Answer 1

Check out the program autossh for automatic reconnection. screen will not mess up because you always specify external commands and flags for those commands after screen specific flags.