To preface this I have full permission to do anything I want to any service I can find on this network as it's part of a course I'm doing in Ethical Hacking. I also want to mention that I'm quite the novice when it comes to information security and hacking in general but I'm familiar with a lot of the methods used on a beginner level.
Whilst exploring this network that has been set up I found multiple open telnet ports on different hosts in the network, but when trying to bruteforce my way in I noticed that they behave differently (some time out after 3 attempts, some don't time out at all but have very slow respose time etc). I've been trying to use Hydra to bruteforce this but it appears as if it returns false negatives constantly. From what I've been able to gather it is because Hydra doesn't automatically know whether a login failed or succeeded, in other words you have to tell Hydra what a bad login looks like (error message such as "login failed" etc.)
What I haven't been able to find however is how do I instruct Hydra what a bad telnet login looks like? I was able to find examples using HTTP-requests but haven't been able to translate this into telnet and would really appreciate any guidance!