Telnet vs Netcat - OSGI Console

Question

I'm facing an issue where I have an OSGI console listening on port 55555, and a bash script that connects on such console using netcat (e.g.: echo "ss" | nc localhost 55555), to get the plugin list running on it.

From the time I've updated OSGI files to a new version, netcat has started received weird characters instead of the interactive console it used to receive. But, if I connect using windows Telnet (connecting on OSGI Console remotely), everything works fine just like before updating the OSGI files.

Does someone knows what telnet does that netcat doesn't when connects on that OSGI console?

As requested, below you can see how I executed both commands, windows em linux, and its returns:

c:/telnet server1 55555
osgi>_

user@server1: nc localhost 55555
ÿûÿûÿýÿýss

Piping through a cat -v: 
user@server1: nc localhost 55555 | cat -v
M-^?M-{^AM-^?M-{^CM-^?M-}^_M-^?M-}^X

Getting an hexadecimal return:     
user@server1: nc -x hexa.log -t localhost 55555
user@server1: cat hexa.log
[0000]   FF FB 01 FF FB 03 FF FD   1F FF FD 18  ........ ....

try adding `-t` option to `nc` to make it do telnet negociation. — meuh, Sep 17 '15 at 18:12
perhaps it is using a different character encoding to before. pipe some of the `nc` output through `cat -v` and edit your post to show what you are getting. — meuh, Sep 17 '15 at 18:56
Well that's unexpected. It looks a bit like telnet negociation, but not enough. It might be better in hex (`nc -x /tmp/x`), when I would expect some 3 byte commands like `ff fd 03 ff fb 18`. Don't you have telnet on the linux to try? And with `nc -t` do you get anything different? — meuh, Sep 18 '15 at 17:57
Hexa results added. With or without -t parameter the results are the same. I don't have telnet command, but I've tried using a java class that connects through telnet and it worked fine. — VeryNiceArgumentException, Sep 21 '15 at 13:24
I stopped searching for a solution at that time because I needed a quick solution, and then I created a java class to do the work. And it still doing the work so far :) — VeryNiceArgumentException, Feb 25 '16 at 12:16

score 0 · Answer 1 · answered Mar 23 '22 at 18:38

0

Try netcat -t from the manual:

-t           enable telnet negotiation

or try expect: How to automate telnet session using Expect?

answered Mar 23 '22 at 18:38

gabor.zed

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Telnet vs Netcat - OSGI Console

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