Vulnerability Development mailing list archives
Re: A Strang bug using Ctrl-N, perhaps a way to deny service on a shell
From: Frank de Lange <secf-frank () unternet org>
Date: Sun, 16 Dec 2001 19:25:17 +0100
On Sun, Dec 16, 2001 at 02:22:27AM -0500, Ben Allen wrote:
(This is a post that I sent to BugTraq) I've found a bug. I'm not sure what the bug is in. Since it is so widely found I can't find out what it is. For an example telnet into any SMTP server you like from a unix prompt. I've only tested from OpenBSD 3.0 Current. Now enter this is: ^N^N^N <Return> ^N <Return> ^N
Those 'weird characters' are the result of your terminal switching to the 'alternate character set' (a.k.a. G1 character set) when it saw that ctrl-n (also known as 'shift-in') passing by. This is a VT100 feature. To go back to the normal (G0) character set, enter the following sequence: <ctrl-v><ctrl-o> <enter> The ctrl-o is also known as 'shift out'. Sometimes you also have to use: stty sane This will reset the terminal to a 'sane' state. It will not, however, change the character set. For that you need to enter the sequence mentioned above. You can provoke the switch to the G1 character set by entering: <ctrl-v><vtrl-n> <enter> //Frank -- WWWWW _______________________ ## o o\ / Frank de Lange \ }# \| / \ ##---# _/ <Hacker for Hire> \ #### \ +31-320-252965 / \ secf-frank () unternet org / ------------------------- [ "Omnis enim res, quae dando non deficit, dum habetur et non datur, nondum habetur, quomodo habenda est." ]
Current thread:
- A Strang bug using Ctrl-N, perhaps a way to deny service on a shell Ben Allen (Dec 16)
- Re: A Strang bug using Ctrl-N, perhaps a way to deny service on a shell Erik Fichtner (Dec 16)
- Re: A Strang bug using Ctrl-N, perhaps a way to deny service on a shell Frank de Lange (Dec 16)
- RE: A Strang bug using Ctrl-N, perhaps a way to deny service on a shell Ben Allen (Dec 16)