Support scanning with external ssh command

[kotakanbe]

-ssh-external option

Vuls supports different types of SSH.

By Defaut, using a native Go implementation from crypto/ssh.
This is useful in situations where you may not have access to traditional UNIX tools.

To use external ssh command, specify this option.
This is useful If you want to use ProxyCommand or chiper algorithm of SSH that is not supported by native go implementation.

[sbkg0002]

Can you provide an example of a .ssh/config with ProxyCommand?

I use a bastion host in my .ssh/config but I can't get it to work with vuls:

Host target
  Hostname 192.168.1.3
Host bastion
 ForwardAgent yes
Host * !bastion
  User vuls
  ProxyCommand ssh bastion -W %h:%p
  IdentityFile ~/.ssh/key.pem

If is use this as a config.toml, I get error 255 (Unable to connect via SSH)

[servers]
[servers.target]
host = "target"
port = "22"
user = "vuls"
keyPath = "~/.ssh/key.pem"

I use vuls -external-ssh.