correctly parse "+" in config files

[RyanJarv]

Running the following with "HostkeyAlgorithms +ssh-dss" set in ~/.ssh/config will result in a "Net::SSH::Exception: could not settle on host_key algorithm" error when connecting to an ubuntu14.04 instance (haven't tested against any other nodes).

Net::SSH.start('1.2.3.4', 'ubuntu', {:timeout=>10, :auth_methods=>["publickey"], :keys_only=>true, :host_key_alias=>"host_key_alias", :key_data=> ["ssh_private_key"]})

This is only an issue with net-ssh version 3.0.2, when using 2.9.2 or using OpenSSH I am able to connect without issue. Removing the "HostkeyAlgorithms +ssh-dss" from my ssh config also fixes the issue as long as you are using a rsa key, dss is deprecated on newer versions of OpenSSH which makes this line necessary in some cases.

[mfazekas]

Can you please add a :verbose=>:debug and post log?

[RyanJarv]

Yep, here you go.

irb(main):006:0> Net::SSH.start('host.name', 'user', {:timeout=>10, :auth_methods=>["publickey"], :keys_only=>true, :host_key_alias=>"host_key_alias", :key_data=> ["ssh_private_key"], :verbose => :debug})
D, [2016-02-28T16:44:27.680672 #64621] DEBUG -- net.ssh.transport.session[3fc4ca1480ec]: establishing connection to host.name:22
D, [2016-02-28T16:44:27.917419 #64621] DEBUG -- net.ssh.transport.session[3fc4ca1480ec]: connection established
I, [2016-02-28T16:44:27.917546 #64621]  INFO -- net.ssh.transport.server_version[3fc4ca145694]: negotiating protocol version
D, [2016-02-28T16:44:28.010825 #64621] DEBUG -- net.ssh.transport.server_version[3fc4ca145694]: remote is `SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.3'
D, [2016-02-28T16:44:28.010926 #64621] DEBUG -- net.ssh.transport.server_version[3fc4ca145694]: local is `SSH-2.0-Ruby/Net::SSH_3.0.2 x86_64-darwin12.0'
W, [2016-02-28T16:44:28.011104 #64621]  WARN -- net.ssh.transport.algorithms[3fc4ca144104]: unsupported host_key algorithm: `["+ssh-dss"]'
D, [2016-02-28T16:44:28.094146 #64621] DEBUG -- socket[3fc4ca145ce8]: read 1240 bytes
D, [2016-02-28T16:44:28.094236 #64621] DEBUG -- socket[3fc4ca145ce8]: received packet nr 0 type 20 len 1236
I, [2016-02-28T16:44:28.094268 #64621]  INFO -- net.ssh.transport.algorithms[3fc4ca144104]: got KEXINIT from server
I, [2016-02-28T16:44:28.094351 #64621]  INFO -- net.ssh.transport.algorithms[3fc4ca144104]: sending KEXINIT
D, [2016-02-28T16:44:28.094441 #64621] DEBUG -- socket[3fc4ca145ce8]: queueing packet nr 0 type 20 len 1548
D, [2016-02-28T16:44:28.094492 #64621] DEBUG -- socket[3fc4ca145ce8]: sent 1552 bytes
I, [2016-02-28T16:44:28.094512 #64621]  INFO -- net.ssh.transport.algorithms[3fc4ca144104]: negotiating algorithms
Net::SSH::Exception: could not settle on host_key algorithm
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/algorithms.rb:328:in `negotiate'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/algorithms.rb:303:in `negotiate_algorithms'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/algorithms.rb:199:in `proceed!'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/algorithms.rb:191:in `send_kexinit'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/algorithms.rb:146:in `accept_kexinit'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:202:in `block in poll_message'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:180:in `loop'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:180:in `poll_message'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:217:in `block in wait'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:215:in `loop'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:215:in `wait'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh/transport/session.rb:87:in `initialize'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh.rb:225:in `new'
    from /opt/chefdk/embedded/lib/ruby/gems/2.1.0/gems/net-ssh-3.0.2/lib/net/ssh.rb:225:in `start'
    from (irb):6
    from /opt/chefdk/embedded/bin/irb:11:in `<main>'

[mfazekas]

The issue is that we don't understand the "+" in HostkeyAlgorithms
The user-provided string may begin with '+' to indicate that it should be appended to the default.