How to monitor all outgoing requests/connections from your GNU/Linux machine

netstat -nputw;

The “netstat” command is a network utility tool used to display information about active network connections, including the protocol used (TCP or UDP), the local and remote addresses and port numbers, and the current state of the connection.

The options used in this command are as follows:

  • “n” displays addresses and port numbers in numerical form rather than converting them to hostnames and service names.
  • “p” shows the process ID (PID) and program name using the connection.
  • “u” displays UDP connections.
  • “t” displays TCP connections.
  • “w” displays raw sockets.
  • “;” separates the command from other commands that may follow.

Therefore, the command netstat -nputw; will display all current network connections on the machine, including the corresponding processes and raw socket connections, in a numerical format without resolving hostnames and service names.

Mount a Windows share on a GNU/Linux server

sudo mount -t cifs //$WINDOWS_FILE_SERVER/$SHARED_FOLDER /var/www/bytefreaks.net/shared/ -o username=remoteUser,password='123abc',domain=bytefreaks.net,file_mode=0777,dir_mode=0777;

The command sudo mount -t cifs //$WINDOWS_FILE_SERVER/$SHARED_FOLDER /var/www/bytefreaks.net/shared/ -o username=remoteUser,password='123abc',domain=bytefreaks.net,file_mode=0777,dir_mode=0777 is used to mount a shared folder from a Windows file server onto a Linux system.

To break down the command further, here is a detailed explanation of each component:

sudo – this command is used to run the following command as a superuser or root. It is required in this instance as mounting requires administrative privileges.

mount – the mount command is used to mount a file system onto a directory in the Linux file system hierarchy.

-t cifs – this option specifies the type of file system that is being mounted. In this case, it is the Common Internet File System (CIFS), which is used for file sharing between Windows and Linux systems.

//$WINDOWS_FILE_SERVER/$SHARED_FOLDER – this is the network path to the shared folder on the Windows file server. The $WINDOWS_FILE_SERVER and $SHARED_FOLDER are placeholders for the actual Windows file server name and shared folder name, respectively.

/var/www/bytefreaks.net/shared/ – this is the mount point, or the location in the Linux file system hierarchy where the shared folder will be mounted.

-o username=remoteUser,password='123abc',domain=bytefreaks.net,file_mode=0777,dir_mode=0777 – these are the mount options that are specified when mounting the shared folder.

The username option specifies the username of the remote user that has access to the shared folder. In this case, the remote user is named remoteUser.

The password option specifies the password for the remote user.

The domain option specifies the domain or workgroup that the Windows file server belongs to. In this case, the domain is bytefreaks.net.

The file_mode and dir_mode options specify the permissions that should be set on the files and directories within the mounted shared folder. In this case, both are set to 0777, which means that all users have full read, write, and execute permissions on all files and directories within the mounted shared folder.

In summary, the sudo mount -t cifs //$WINDOWS_FILE_SERVER/$SHARED_FOLDER /var/www/bytefreaks.net/shared/ -o username=remoteUser,password='123abc',domain=bytefreaks.net,file_mode=0777,dir_mode=0777 command is used to mount a shared folder from a Windows file server onto a Linux system with the specified mount options.

Do SFP transceivers have a MAC address or does the address belongs to the SFP port?

SFP (Small Form-factor Pluggable) transceivers do not have a MAC address. The MAC address is assigned to the network interface controller (NIC) or network adapter, which is the hardware component responsible for connecting a device to a network.

The SFP transceiver is a hot-swappable input/output device that plugs into a port on a network switch, router, or other networking devices and allows the device to transmit and receive data over fiber optic or copper cables. The SFP port to which the SFP transceiver is connected is typically assigned a unique MAC address by the device manufacturer.

Therefore, the MAC address belongs to the device’s network interface using the SFP port, not the SFP transceiver itself.

A solution to running out of memory while executing mysqldump

Are you trying to perform a mysqldump on a large table and running out of memory every time? This can be a frustrating experience. Even if you try to use the –quick parameter, you may still run out of memory. In this blog post, we will discuss a solution to this problem.

One option is to create a swap file to add more swap space. A swap file differs from a swap partition but can be accessible and dynamic. In the following steps, we will show you how to create a swap file.

First, create an empty file. This file will contain virtual memory contents, so make sure to create a file big enough for your needs. The following command will create a 1GiB file, which means +1GiB swap space for your system:

dd if=/dev/zero of=/media/tux/bigdisk/swapfile.img bs=1024 count=1M;

If you want to create a 3GiB file, change the count value to count=3M. Refer to the man dd for more information.

Next, make a “swap filesystem” inside your new swap file using the following command:

mkswap /media/tux/bigdisk/swapfile.img;
chmod 600 /media/tux/bigdisk/swapfile.img;
chown root:root /media/tux/bigdisk/swapfile.img;

To ensure that your new swap space is activated while booting up your computer, add it to the filesystem configuration file /etc/fstab. Add the following line to the end of the file:

/media/tux/bigdisk/swapfile.img swap swap sw 0 0

This is recommended because other filesystems (at least one that contains a swap file) must be mounted in read-write mode before we can access any files.

Finally, you can either reboot your computer or activate the new swap file manually with the following command:

swapon /media/tux/bigdisk/swapfile.img;

If everything goes well, you should see that more swap space is available for use. You can use the following commands to check your new swap and confirm that it is active:

cat /proc/swaps;

This should display something like:

Filename                           Type       Size    Used    Priority
/swapfile                          file       16777212 1048796    -2
/media/tux/bigdisk/swapfile.img    file       67108860 0          -3

You can also use the following command to check your swap usage:

grep 'Swap' /proc/meminfo;

This should display something like:

SwapCached:         132456 kB
SwapTotal:        83886072 kB
SwapFree:         82837276 kB

Creating a swap file can be an effective solution to running out of memory while performing a mysqldump on a large table. It is a simple, dynamic solution that can be implemented easily on most Linux systems. Following the steps outlined in this post, you should be able to create a swap file and add more swap space to your system.