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Old 10-06-2005, 09:50 AM   #1
Registered: Feb 2005
Location: Ottawa/Montréal
Distribution: Slackware + Darwin (MacOS X)
Posts: 468

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ssh login reverse mapping failed, should I worry?

Address maps to, but this
does not map back to the address - POSSIBLE BREAKIN ATTEMPT!
I just got this when logging in to my Slackware box from my campus wifi (first time I've used the campus wifi, new system). Could that be the culprit?

PS is the address of my server as reported by ifconfig | grep ppp0.
Old 10-06-2005, 05:44 PM   #2
Registered: Apr 2002
Posts: 498

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It just means that the reverse DNS for your campus wifi is not properly configured and SSH could not determine a hostname for the IP in question. Personally, I don't know why SSH gripes about this, but I'm sure there is a (somewhat) legitimate reason somewhere.
Old 10-06-2005, 06:34 PM   #3
Senior Member
Registered: Mar 2003
Location: Beautiful BC
Distribution: RedHat & clones, Slackware, SuSE, OpenBSD
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From the sshd_config manpages
UseDNS Specifies whether sshd should lookup the remote host name
and check that the resolved host name for the remote IP
address maps back to the very same IP address.
The default is "yes"

Last edited by ppuru; 10-06-2005 at 06:36 PM.
Old 10-16-2005, 10:27 AM   #4
Registered: Feb 2005
Location: Ottawa/Montréal
Distribution: Slackware + Darwin (MacOS X)
Posts: 468

Original Poster
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I had a feeling it was UseDNS, but I'm never sure whether it's the sshd or ssh that outputs those messages (i.e., I wasn't totally sure whether it was my end or the server end that was complaining about the DNS entry being wrong).



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