Setting UseDNS in sshd_conf

[JustSomeGuy]

I was wondering if anyone could shed some light on this issue.
In cPHulk, it says "UseDNS was detected as being enabled for SSHD which causes problems with whitelisting IPs for cPHulkd. UseDNS has been set to "no" to prevent issues."
My problem is that inside sshd_conf, it sets it to: UseDNS no
When I try to restart sshd, I get the following:
/etc/ssh/sshd_config: line 99: Bad configuration option: UseDNS
/etc/ssh/sshd_config: terminating, 1 bad configuration options

At that time, sshd will not restart.
Any ideas???
Thanks in advance

 

[cPanelMichael]

Hello

I have seen some cases where custom entries to the /etc/ssh/sshd_config file have resulted in the error message that you reported. Could you let us know what Operating System you are using? You can check this with a command such as:

# cat /etc/redhat-release

Also, you may want to try using a known default /etc/ssh/sshd_config file and then making the change again to see if it allows SSH to restart normally.

Thank you.

 

[JustSomeGuy]

CentOS release 5.9 (Final)
The only change that I have done is:
Port ??? I've set the port to a different one to hide
Protocol 2

As for the default file, do you know where I could fine one?

 

[cPanelMichael]

You could simply remove the "UseDNS" line completely, as it appears your version of OpenSSH does not support it.

Thank you.

 

[JustSomeGuy]

Yes I do remove it but at times, when updates are done, it will add that line to the config file and I can not login. Just frustrating

 

[cPanelMichael]

Could you open a support ticket so we can address this issue and open an internal case if necessary?

Submit A Ticket

Please post the ticket number here so we can track the issue.

Thank you.

 

[JustSomeGuy]

Thank you.
Ticket #4171527

 

[cPanelMichael]

To update, it was determined in the ticket that the OpenSSH RPMs installed on this server were not the standard ones provided on CentOS machines. The error message reported appears to have been related to that, as it was not reproducible in a similar test environment.

Thank you.

 

[Data 1]

OK I have the same issue on one server. Ticket or can you post the fix?

 

[cPanelMichael]

OK I have the same issue on one server. Ticket or can you post the fix?

Which OS is installed on this system? Are you using the standard OpenSSH RPM provided by your OS?

Thank you.

 

[georgeb]

You can simply do: (until you have a solution from cPanel):

chattr +i /etc/ssh/sshd_config

and updates can't change anymore this

or add a line to /scripts/postupcp and remove the line containing UseDNS (using sed command, and restart sshd service)

Regards

 

[cPanelPeter]

Hello,

I do not recommend setting the immutable bit on any files. This can cause all kinds of problems within cPanel/WHM.
As cPanelMichael already stated, this usually means your OS is running a version of OpenSSH that does not understand the UseDNS option.

We know CentOS uses RPM's for OpenSSH that will accept UseDNS configuration options, so if you're running another OS, you need to make sure that the UseDNS option is available. (it is in most modern operating systems).