I'm trying to login to a telnet server that prompts for username then password and it is randomly failing after entering the correct username with the error for either "invalid username" or "invalid password". It always works from linux terminal running
telnet though.

Wireshark revealed that the only difference is that putty sends the username in one frame and then follows that with a frame containing only /r/n. Linux terminal always sends "username/r/n" in the single frame. I've since confirmed that sending all in
one frame works and not doing this fails most of the time (sometimes it is quick enough the server accepts it).

There appears to be no configuration option that succeeds in making putty send the username and /r/n in a single frame. This issue exists in both the latest windows and latest Linux(debian) versions. It is also in the latest version of Kitty.

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Isaac Brown <isaac.a.brown@gmail.com> wrote:

I'm trying to login to a telnet server that prompts for username then passw= >ord and it is randomly failing after entering the correct username with the=
error for either "invalid username" or "invalid password". It always works= from linux terminal running telnet though.

Wireshark revealed that the only difference is that putty sends the usernam= >e in one frame and then follows that with a frame containing only /r/n. Lin= >ux terminal always sends "username/r/n" in the single frame. I've since con= >firmed that sending all in one frame works and not doing this fails most of=
the time (sometimes it is quick enough the server accepts it).

This is an RFC violation. The server should not care where the frame boundaries are. What server is it that is having this problem?

Are you sure it's not using line mode here? Putty does not support line mode very well.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

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