LinuxHostingSupport

On a VPS, there are 2 ways to mount OR secure /tmp and /var/tmp partitions with the noexec,nosuid option. One way is to mount these partitions from the Host Node (hosting provider can do this) and the other way is to mount them from within the VPS.

1) Login to the Node server and execute the following command:

# vzctl set VEID --bindmount_add /tmp,noexec,nosuid,nodev --save 
# vzctl set VEID --bindmount_add /var/tmp,noexec,nosuid,nodev --save

The “bindmount_add” option is use to mount the partition inside the VPS. The ‘VEID’ is the VPS ID you are working on.

2) The second option is to mount these partition from within the VPS itself. It is useful incase you don’t have access to the Node server. To mount /tmp and /var/tmp from within the VPS, execute:

# mount -t tmpfs -o noexec,nosuid,nodev tmpfs /tmp 
# mount -t tmpfs -o noexec,nosuid,nodev tmpfs /var/tmp

To check the mounted ‘tmp’ partitions, execute

# mount | grep tmp 
 tmpfs on /tmp type tmpfs (rw,noexec,nosuid) 
 tmpfs on /var/tmp type tmpfs (rw,noexec,nosuid,nodev) 

Related Links:

 How to Secure /tmp on Dedicated server?

An update/upgrade on the existing Drupal website may result in a following error message on the website:

"PHP Fatal error:  Call to undefined function user_access() 
 in /home/user/modules/ad/ad.module on line xxx"

The solution is to update a “status” entry in the Drupal Database. Access your Drupal database either from the Mysql prompt OR using a 3rd party application like phpMyAdmin.

1) Open the table called “System”.

2) Search for the entry “modules/user/user.module” in the “filename” column.

3) Change the value of ‘status’ variable from 0 to 1.

4) Save.

This is it.

Note: If the value of ‘status’ variable is already 1, change it to ‘0’ and then reset back to ‘1’. It should fix the issue.

What is Frame Forwarding and How it is set?

A few lines of Explanation:

Frame forwarding (redirection) of a domain is different than normal forwarding of a domain.

In Frame Forwarding, the visitors are redirected to another site, but the destination address is not displayed in the address bar, so they are not aware of the redirection as opposed to “Normal Forwading” (also called Parked domain).

In Normal Forwading the web site visitors are redirected to another site and the destination address is displayed in the address bar, so the visitor is aware about the redirection.

For example, suppose the main website is abc.com and we frame forwarded xyz.com to it. When we access xyz.com, the URL in the address bar of the browser will stay as it is and the contents will be fetched from abc.com. The user won’t notice the redirection.

Solution:

Using the above domain names as example, in order to set Frame Forwarding for xyz.com, first add the domain on the server as we normally do and add the following code in the index.html file

<frameset rows="100%", *' frameborder=no framespacing=0 border=0> 
<frame src="http://www.abc.com/"></frame> 
</frameset>

This is it.

A Drawback of the above method and a Solution for it:

As you will be setting up a redirection in the index.html file, any other file/directory accessed using a direct URL ( i.e. for example: xyz.com/anyfilename) will result in a “404 Not Found” error.This is because the request will bypass the redirection set in the index.html file and will search for the file under the xyz.com itself.

To overcome this problem, add xyz.com as a “ServerAlias” in the VirtualHost entry of abc.com. Edit the Apache configuration

vi /etc/httpd/conf/httpd.conf

Search for the VirtualHost entry of abc.com and make sure the “ServerAlias” line look like the following

ServerAlias www.abc.com xyz.com www.xyz.com

Save the file and restart the Web server

service httpd restart

Now, directly accessing a file or directory of a target domain using the alias domain name will also work.

Sometimes SSH won’t allow you to login though correct login credentials has been submitted and the SSH access logs says the following:

sshd: PAM _pam_load_conf_file: unable to open /etc/pam.d/system-auth 
sshd: PAM unable to dlopen(<*unknown module path*>) 
sshd: PAM [error: <*unknown module path*>: cannot open shared object 
file: No such file or directory] 
sshd: PAM adding faulty module: <*unknown module path*>

The SSH access logs are saved in the /var/log/secure file. The logs clearly indicates that the file “system-auth” is missing from the “/etc/pam.d/” directory. This file is responsible for calling the PAM modules and is very much needed for authentication.

root@server [~]# ls -la /etc/pam.d/system-auth 
 /bin/ls: /etc/pam.d/system-auth: No such file or directory

In order to fix the issue, copy over the ‘system-auth’ file from another server and you should be able to SSH in immediately.