Solved

Allow userok@ip_good, Deny userok@any_other_ip and Allow *@*

Posted on 2010-08-25
5
383 Views
Last Modified: 2013-11-17
Is it possible? I'm running sshd on Aix6.1

Scenario:
ALLOW only access from: userok@ip_good
DENY access from userok@*
and
ALLOW acces from *@*

Thanks
0
Comment
Question by:sminfo
  • 2
  • 2
5 Comments
 
LVL 77

Accepted Solution

by:
arnold earned 250 total points
ID: 33521779
I've not used AIX, but do not think it is possible.
You can use the hosts.allow/hosts.deny if your SSH has tcp_wrappers to deny based on IP.

If sshd with tcp_wrappers handles the user@ip,
The other issue is that deny supersedes allows such that an entry in Allow userok@ip_good will be ignored because of the entry in DENY: sshd:userok@*  

I've not tested whether username@ is even an option which seems rather problemativ as it will be a nightmare to track down. i.e. user is active everywhere except the user can not connect.
0
 
LVL 68

Assisted Solution

by:woolmilkporc
woolmilkporc earned 250 total points
ID: 33521801
Hello again,
I fear this will not be feasible.
All "DenyUsers user@host" directives in sshd_config are processed before the "Allow..." directives, and once a user's access is denied it will not be granted back to them depending on a particular host.
wmp
0
 

Author Comment

by:sminfo
ID: 33522281
Hi wmp and arnold,

The fact is I have a user 'userok' who uses to connect all my servers and run certain commands via sshd. I want to block access in my servers  from userok@* but let only access to sshd to userok@ip_good. :-)
Am I asking too much? I've searched a lot but can find a solution to make this possible.
0
 
LVL 68

Expert Comment

by:woolmilkporc
ID: 33522424
I think we understood your question and we answered it: No, it is not possible to achieve what you desire.
0
 
LVL 77

Expert Comment

by:arnold
ID: 33522523
You are trying to combine two separate functions into working in tandem.
I.e. TCP based access list (tcp_wrappers) allows access control to SSHD.
You can use the hosts.allow and hosts.deny to deny sshd:all and in the hosts.allow add the SSHD: IPrange, ips, etc. that you want to allow.

The SSH level restriction for user and group access will handle that side using AllowGroups, AllowUsers, DenyGroups, DenyUsers will process the deny first.

The problem is you seemingly want to limit access of a specific user to a specific IP.

An option you could have is to replace the shell configured for userok.
instead of /bin/bash, you could have an intermediary shell which is a script that will check whether the user is connecting from ip_good by checking the SSH_client env source. If it is, the script runs bash. If it is not, the script exits which will terminate the ssh session.

You would need to add this overlay/wrapper script on every system as well as modify the userok /etc/passwd entry if it is not centrally managed using NIS, NIS+, LDAP, etc.
0

Featured Post

Master Your Team's Linux and Cloud Stack!

The average business loses $13.5M per year to ineffective training (per 1,000 employees). Keep ahead of the competition and combine in-person quality with online cost and flexibility by training with Linux Academy.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Java performance on Solaris - Managing CPUs There are various resource controls in operating system which directly/indirectly influence the performance of application. one of the most important resource controls is "CPU".   In a multithreaded…
It’s 2016. Password authentication should be dead — or at least close to dying. But, unfortunately, it has not traversed Quagga stage yet. Using password authentication is like laundering hotel guest linens with a washboard — it’s Passé.
In a previous video, we went over how to export a DynamoDB table into Amazon S3.  In this video, we show how to load the export from S3 into a DynamoDB table.
This demo shows you how to set up the containerized NetScaler CPX with NetScaler Management and Analytics System in a non-routable Mesos/Marathon environment for use with Micro-Services applications.

809 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question