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Possible bug with SSH banner?

Randy
2018-05-08
2018-05-11
  • Randy

    Randy - 2018-05-08

    HI,
    I've recenlty come upon putty-nd, and started using it .. so far I like it. I've noticed, however, that when I connect to certain systems that I know have banner's defined in ssh, they are not being presented to the me .. just the password prompt.

    This doesn't seem to stop anything from working, but in our environment the banners tend to provide pretty important info when logging in .. so I'd like to see them. :) (In my case, I'm specifically connecting to ubuntu 16 servers)

    The "Display pre-authentication banner (SSH-2 only)" option IS checked for the session.

    Putty renders these messages, so not seeing them is a departure from putty that I didn't expect or even notice at first. Perhaps there is just another setting that I need to enable somewhere, or something silly I just missed?

    Thanks

     
  • Noodle

    Noodle - 2018-05-09

    fixed in the attachment. If everything is fine, it will be release in next release.
    The attachment also provides flow control on the server output, which means the cmd with lots of output can't make putty-nd dead. I got a crash on exit once, but it don't shown again. Maybe you can help to test.

     
  • Noodle

    Noodle - 2018-05-09

    And I took some time to see if the banner can be shown before the login prompt.
    The Answer is NO.
    The server only sends the banner message after SSH_MSG_USERAUTH_REQUEST is received, which must specified a user name.
    https://www.ietf.org/rfc/rfc4252.txt
    byte SSH_MSG_USERAUTH_REQUEST
    string user name
    string service name

    The openssh can make it because it use the os user name as the user name.

     
  • Randy

    Randy - 2018-05-09

    At first glance, this did it ... the banners are working to targets where they weren't yesterday. It even restored the lack of login user name "echo" when passing the username via a command line launch.

    Thanks!

     
    • Noodle

      Noodle - 2018-05-10

      OK. It is verbose mode actually. It can make it by -v in command line with previous version.

       
      • Randy

        Randy - 2018-05-10

        Are you saying that the -v switch would have shown the banner on the previous version?, or that it would have just echo'd the username?

         
        • Noodle

          Noodle - 2018-05-11

          yes, the -v switch would have shown the banner on the previous version.

           

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