From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Woods Subject: Re: Is it possible to trace back from where a user comes Date: Wed, 29 Oct 2003 00:50:12 -0800 Sender: linux-c-programming-owner@vger.kernel.org Message-ID: <5.2.1.1.0.20031029004509.0194e350@no.incoming.mail> References: Mime-Version: 1.0 Return-path: In-Reply-To: List-Id: Content-Type: text/plain; charset="us-ascii"; format="flowed" Content-Transfer-Encoding: 7bit To: Holger Kiehl Cc: linux-c-programming@vger.kernel.org At 10/29/2003 08:29 AM +0000, Holger Kiehl wrote: >I have written a small program that allows a user to do some >configuration. Now everytime the user does configure something it gets >logged to a log file. Usually when someone comes from a remote machine I >took the environment variable DISPLAY and if that is not there the output >from "who am i", to determine from where the user comes. However this does >not work reliably since DISPLAY is set to localhost when the user is using >ssh, also "who am i" does not always tell me from where a user comes. >Another problem is when the user first logs in on say host1 then to host2 >and then to host3. Is there a way to determine that the user comes from >host1? The SSH_CLIENT environment variable is always set to the last host, >so this can not be used. SSH_CONNECTION is not set so this can also not be >used. I also looked at struct utmp it to does not provide the information, >it is also not very portable since the structure differs a lot from system >to system. > >So is there a way to determine from where a user comes? In short, no. The practical answer to what I think you want is "authentication". That authentication can come from a variety of mechanisms (e.g. password, Kerberos token, client certificate, smart card, etc.) but they all boil down to some form of userid and password (i.e., a shared secret). -- Jeff Woods "Errors creep into everything, and the only way to expunge them is to have any bit of work reviewed by a few others." -- Wirt Atmar, 10-27-2001 "The great thing about Open Source software is that you can have any color screen of death that you want." -- Gavin Scott, 08-22-2000