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WebMO Support Forum » Administering WebMO » Remote Server Manager (Pro) » Could not contact remote server: verify passwordless SSH/RSH « Previous Next »

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Byron Millet
Unregistered guest
Posted on Friday, December 30, 2011 - 2:27 pm:   

Hello,

I am trying to set up remote servers on Webmo Enterprise using several Slackware Linux boxes and keep running into the same message as in the subject line.

I checked the ssh logs (/var/messages) and the main server shows no logs, but the remote server I am trying to connect to shows the following message:

Did not receive identification string from xxx.xxx.xxx.xxx (where this is the ip of the main server).

I changed the log level to verbose and got 2 extra lines that dont seem to tell me much:

Set /proc/self/oom_adj to 0
Connection from xxx.xxx.xxx.xxx port xxxxx
Did not receive identification string from xxx.xxx.xxx.xxx


where the ip numbers were from the main server and the port number changes each time.
That is to say the port number from the last 5 log messages was 54349, 54350, 54351, 54352, and 54353.

I'm really not sure what is causing this as I am able to ssh to and from these machines without a password using the username where we installed webMO.

If anyone has any suggestions, I would be very grateful.


Byron
JR Schmidt
Moderator
Username: Schmidt

Post Number: 218
Registered: 11-2006
Posted on Saturday, December 31, 2011 - 10:32 am:   

I have never seen this one before.

You might verify if WebMO is actually running under the UID of the account on which it is installed, e.g. is suEXEC functioning. I'm not sure if suexec is enalbed / compiled by default for slackware (not familiar with that distro). There should be an suexec log file along with the normal Apache (httpd.conf) log files.

If suexec is NOT enabled, then WebMO will be running as user 'www' or 'apache', etc. As such, the passwordless SSH will fail (since no keys are set up for that account).

All the references to the "did not receive identification string from.." SSH errors talk about proxies, etc. Does this apply to you?
Byron Millet
Unregistered guest
Posted on Saturday, December 31, 2011 - 3:30 pm:   

Suexec is not enabled by default in Slackware, but I recompiled apache with suexec.

From /var/log/httpd/error_log and suexec_log I have verified that it is running as the proper username (chemlab).

However, in the process I noticed that the uid is slightly different from one server to the other.
The name is the same (chemlab), but the nubmer is different (1002 and 1004); could that cause a problem.

I also noticed that the date/time is not correct on the main server and is different on the other machines so I need to fix that.


Also, will I need suexec running on all of the remote servers as well? I currently only have it enabled on the main server.



Thanks,

Byron
Byron Millet
Unregistered guest
Posted on Saturday, December 31, 2011 - 3:31 pm:   

I forgot to answer your question above...

We are not using proxies in this setup.

Byron
JR Schmidt
Moderator
Username: Schmidt

Post Number: 219
Registered: 11-2006
Posted on Monday, January 02, 2012 - 9:43 am:   

Just to clarify:

1) Login to the web server machine on the 'chemlab' account.
2) Do an "ssh -l chemlab <compute_server>"

and it logs in, no password required. Note that for purposes of SSH passwordless login, the fully qualified server name (server.domain.edu) is different than the short name (server).

Please also check the "/var/log/secure.log" file for more details about why / if the remote login failed. You might also check the WebMO error log, in <webmo_cgi_base>/errors.
Byron Millet
Unregistered guest
Posted on Monday, January 02, 2012 - 1:16 pm:   

Your clarification is correct.
I can log into the web server machine on the 'chemlab' account.
Then I am able to do 'ssh -l chemlab <compute_server>'

and it logs in with no password required or asked for.
I have verified that this works both to and from the web server and compute servers using both the full server name and the short names.

When setting up the remote server in webmo, I am using the full server name in the Hostname field.


I checked /var/log/secure and saw only messages regarding my recent use of the su command from my terminal.

I checked the /home/chemlab/webmo/errors log file and there doesn't appear to be any relevant messages there.
This log file has several lines of the same error:
Array @atoms missing the @ in argument 1 of push() at parse_gamess.cgi line 525

This error appears to originate from several of the webMO cgi scripts such as jobmgr.cgi, choose_engine.cgi, as well as servermgr_admin.cgi
A new instance of this error is logged each time I click the "Add" button in the Remote Server Manager.


I just finished changing the uid number for the chemlab user to the same number across all the machines and it did not help.


I still need to set up a proper time server on the main machine and set the other compute servers to get their time/date from the main server. Hopefully that will help the situation.


I have been checking all the log files I can to see if any of them log anything after I click the Add button and noticed that /var/log/httpd/error_log logs the following each time it is clicked:

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] $# is no longer supported at (eval 33) line 1, <interfacefile> line 33., referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] Bareword found where operator expected at (eval 33) line 1, near "$# added", referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] \t(Missing operator before added?), referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] $# is no longer supported at (eval 33) line 1, <interfacefile> line 33., referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] Bareword found where operator expected at (eval 33) line 1, near "$# added", referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

[Tue Jan 03 01:13:05 2012] [error] [client <web_server_ip>] \t(Missing operator before added?), referer: http://<web_server>/~chemlab/cgi-bin/webmo/servermgr_admin.cgi

I believe that these messages may be pointing to something, but I haven't yet looked at the servermgr_agmin.cgi script.

You can see from the date stamp that the date/time are incorrect.
And I added <web_server_ip> and <web_server> in place of the actual server ip and server name.

Byron
Byron Millet
Unregistered guest
Posted on Wednesday, January 04, 2012 - 1:25 pm:   

I believe I may have found some more info regarding this error.
I think it may be related to some other errors we are getting with our webMO implementation.

I recently moved the webMO files from one server to the other using the guide found on this site in the FAQ: https://www.webmo.net/support/faq.html

We had previously been using webMO with cgi-wrap because when I initially set everything up I was unable to get suexec to work.

After moving webMO to the new server, I removed the cgi-wrap files, recompiled httpd with suexec included, and got everything working (or at least appearing to work) with suexec enabled.

Now we have some additional errors where we are unable to view molecular vibrations or molecular orbitals with webMO.
The implementation on the original server still allows viewing of MOs and vibrational modes, but the new one does not.

For the frequency jobs, we get all of the thermodynamic data as well as the rotational constants, but the view job page does not even show the table with the vibrational modes.

For the molecular orbitals, we do get the table with the molecular orbitals, but we do not get any energy values.
The first orbital energy shows as ARRAY(0xb95c58) Hartree while the rest simply show Hartree.

It appears that webMO is no longer able to read the output files from gaussian properly.
I verified that it is just the webMO on our main server by importing the same output files into the webMO on the old main server and everything works fine there.

the webmo error log shows nothing
but the /var/log/httpd/error_log shows similar errors as above with the (Mising operator before added?) and Bareword found where operator expected. but shows them for the view_job.cgi and import_job.cgi scripts.

The only difference between the two webMO implementations is that the old server is still using cgi-wrap and the new server is using suexec.
Both servers are using webMO with G09 that was installed with all of the same directories and permissions.

Hopefully someone knows something that could help

Thank you,

Byron Millet
JR Schmidt
Moderator
Username: Schmidt

Post Number: 220
Registered: 11-2006
Posted on Wednesday, January 04, 2012 - 1:28 pm:   

I would recommend doing a fresh install of WebMO. You can always migrate over your "user" directory containing the jobs, users, etc. after you get things working. This might simple eliminate the issues.

Lots of things get setup during installation: paths to various programs, etc. If these are different from one server to another it could create issues.

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