1
When a TELNET session is initialised using PuTTY, I see that PuTTY is sending the following characters to the server at the beginning of the connection:
..... .....'.........
I was able to capture this using WireShark. The hex characters are as follows:
ff fb 1f ff fb 20 ff fb 18 ff fb 27 ff fd 01 ff fb 03 ff fd 03
Can you please help me understand why PuTTY sends these characters? I assumed it is something with the connection, but then, these characters are found in the DATA category of the WireShark capture.
Here is a video: https://www.youtube.com/watch?v=WGZru4KPmsM
Note that many "telnet clients" change their behavior depending on what port you use. For example, if you connect to a server on port 23 (the regular Telnet port) they perform active negotiation, but if you connect on some other port (e.g. SMTP or HTTP) they accept passive negotiation but do not send anything on their own. This can be a source of confusion. – user1686 – 2019-10-31T21:34:36.180
And if you use PuTTY to connect to a non-Telnet server... just don't use the Telnet mode at all. That's what the "Raw" mode in PuTTY is for! – user1686 – 2019-10-31T21:35:08.553