I'm aiming to start up a second sshd
instance on a non-privileged port (e.g. 2222) with my own configuration file.
Obviously, the sshd
process can't setuid
so logging in as users other than the one who is running the sshd
daemon is clearly impossible.
However, is it possible to have a working sshd
daemon that will work for the currently running user? For my use case, this would be fine.
I tried booting up an sshd
instance with my own config file and host key and the sshd
process starts up (no complaints about not being root, like some commands), however when I try to connect to that port, the sshd
process dies.
$ /usr/sbin/sshd -dD -h .ssh/id_rsa -p 2222
debug1: sshd version OpenSSH_5.6p1
debug1: read PEM private key done: type RSA
debug1: private host key: #0 type 1 RSA
debug1: setgroups() failed: Operation not permitted
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-dD'
debug1: rexec_argv[2]='-h'
debug1: rexec_argv[3]='.ssh/id_rsa'
debug1: rexec_argv[4]='-p'
debug1: rexec_argv[5]='2222'
debug1: Bind to port 2222 on 0.0.0.0.
Server listening on 0.0.0.0 port 2222.
debug1: Bind to port 2222 on ::.
Server listening on :: port 2222.
debug1: fd 6 clearing O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug1: rexec start in 6 out 6 newsock 6 pipe -1 sock 9
debug1: inetd sockets after dupping: 5, 5
Connection from ::1 port 57670
debug1: Client protocol version 2.0; client software version OpenSSH_5.6
debug1: match: OpenSSH_5.6 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.6
debug1: list_hostkey_types:
No supported key exchange algorithms
debug1: do_cleanup
debug1: do_cleanup
debug1: audit_event: unhandled event 12
The debug1: setgroups() failed: Operation not permitted
line obviously sticks out, but it doesn't die until it tries to accept a connection.