Red Hat Bugzilla – Bug 53551
telnet update to 0.17.6x-18 changes default "mode" behaviour
Last modified: 2008-05-01 11:38:00 EDT
Description of Problem:
When using the updated telnet client to connect to a Bianca/BrickXL (a ISDN dialin router), the default linemode has changed from the behaviour of telnet-0.16-6 (RH 6.2 default).
When using 0.16-6, linemode is negotiated as follows:
Connected to xxxxxxxxxxxxx
Operating with LINEMODE option
Connected to xxxxxxxxxxx
Operating in obsolete linemode
Unfortunately, the router in question does not like the obsolete linemode (this is how I noticed the problem).
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Use telnet to connect to the router in question
2. Issue a telnet escape sequence
3. use "status" to check linemode
telnet is using "obsolete linemode"
telnet should use "LINEMODE"
Looking at a tcpdump output of the connection I noticed that telnet-0.16-6 (the old one) sends one packet more than telnet-0.17 (the new one).
The packet in question is sent from the client to the server, and contains option negotiations.
The options negotiated in 0.16 but not in 0.17 are:
- Do suppress go ahead
- will Terminal Type
- will negotiate about window size
- will Terminal Speed
- will Remote Flow Control
- will Linemode (sic!)
- will New Environment Option
- Do Status
This is almost certainly the same bug as that associated with BugZilla ID
56679, namely that all telnet option negotiation is effectively disabled by
default. Please see my comments and suggested patch and possible workround in
that BugZilla ID for more information.
*** This bug has been marked as a duplicate of 56679 ***