Category Archives: Operating Systems

Linux : Issue with mail aliases “database /etc/aliases.db is older than source file /etc/aliases”

If you are experiencing issues with your local mail aliases, make sure there is no syntax error in /etc/aliases file and have a look at the mail log file :

/var/log/mail.log

1	/var/log/mail.log

You most likely will encounter a message like this one :

postfix/local[15083]: warning: database /etc/aliases.db is older than source file /etc/aliases

1	postfix/local[15083]: warning: database /etc/aliases.db is older than source file /etc/aliases

In that case, simply run the command to rebuild the aliases database… Read More »

Linux : Mail issues after renaming server hostname

If you changed the hostname/FQDN of a Linux server, you may end up with some issues, especially with mailing if some areas were forgotten with that change. Here is a quick procedure involving all the steps you should be looking for. (The following example is based on a Debian Linux system running Postfix MTA.) 1.… Read More »

Windows : Nmap error dnet: Failed to open device eth0

This symptom occurred all of a sudden with Nmap 7.80 and Windows 10 version 1909 (OS build 18363.836), where nmap tries to query using interface “eth0” : Starting Nmap 7.80 ( https://nmap.org ) at 2020-06-30 11:28 Eastern Daylight Time dnet: Failed to open device eth0 QUITTING! It seems that latest Windows updates is involved in… Read More »

Windows : Remote Desktop “The requested session access is denied.”

Having the following login error attempting to establish a RDP session to a Windows server or workstation? The requested session access is denied. The following behavior apply to your case: The user you are using is a part of the Remote Desktop Users group (or allowed to the RDP users) The user is a non-administrator… Read More »

macOS : Where does iTunes store iPhone and iPad backups

Beside the iCloud service, iTunes is the way to go when you need to backup your Apple mobile devices such as iPhone and iPad. If you want to secure the backups taken by iTunes on your computer file system, this article will show you where it is stored on your macOS computer file system. Before… Read More »

Windows : How to configure VLans on Intel network adapter with PowerShell

If you have an Intel card and the necessary “Advanced Network Services (ANS)”, that is bundled with the Intel driver, you have the capability to manage VLans for your network interface with PowerShell. 1. Use the “ipconfig” command to find out the name of your adapter. Example :

PS C:\WINDOWS\system32> ipconfig

Windows IP Configuration

Ethernet adapter Ethernet0:

   Connection-specific DNS Suffix  . :
   IPv4 Address. . . . . . . . . . . : 10.1.1.50
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 10.1.1.1

PS C:\WINDOWS\system32> ipconfig

Windows IP Configuration

Ethernet adapter Ethernet0:

Connection-specific DNS Suffix . :

IPv4 Address. . . . . . . . . . . : 10.1.1.50

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 10.1.1.1

In that case, our adapter name… Read More »

Linux : nfs4_discover_server_trunking unhandled error -512. Exiting with error EIO

Experiencing the following behavior with RHEL/CentOS 7.2 and NFS? NFS folder mount hang and the following output can be observed in logs and dmesg : NFS: state manager: lease expired failed on NFSv4 server 0.0.0.0 with error 10082 NFS: nfs4_discover_server_trunking unhandled error -512. Exiting with error EIO nfsd: last server has exited, flushing export cache… Read More »

Windows : Where does iTunes store iPhone and iPad backups

Linux : How to run Google Chrome as root

By design, Google Chrome cannot be started as root on Linux systems for security reason, which totally make sense. However, there might be some exceptions where it is required. Here is how to make it work. If you need to run it once or really occasionally, you may start it with the following command using… Read More »

macOS : configure: error: C compiler cannot create executables

Having some issues using the GCC compiler? The problem may show up under different circumstances, such as : – Invoking the GCC compiler trying to compile an application manually using “sudo ./configure”. In such case, an output similar as below will be shown :

checking for gcc... gcc
checking whether the C compiler works... no
configure: error: in `/path/to/some/source/folder':
configure: error: C compiler cannot create executables

checking for gcc... gcc

checking whether the C compiler works... no

configure: error: in `/path/to/some/source/folder':

configure: error: C compiler cannot create executables

– Trying to upgrade outdated packages after updating MacPorts (which… Read More »