Pass VLAN traffic to KVM Guests

Recently, I was working on a setup where we need to use two IP ranges for KVM guests and we found that VLAN tagging is the best way to achieve this.
Refer the below diagram for more understanding:

To allow Linux host to be aware of VLAN’s we need to enable 802.1Q tagged queuing:

We can do that using modprobe command as:

modprobe 8021q

This should enable the 802.1Q tagged queuing.

To verify if it’s working you can use the command:

# lsmod | grep 8021q
8021q 21768 0

Now, we know that host can recognize VLAN’s.

Next step is to add network interfaces bind to specific VLAN  in our host.

We have eno1 interface in our host and it needs to use tagged network traffic for VLAN ID 1,2.

eno1 – regular network interface

eno1.1 – virtual interface that use untagged frame from VLAN 1

eno1.2 – virtual interface that use untagged frame from VLAN 2

Now we need to configure eno1.1 interface as:

# vi /etc/sysconfig/network-scripts/ifcfg-eno1.1

In this file we write:





Save and Quit.

For eno1.2 perform the same steps as above.

Now we need to create a bridge interface that will allow us to bridge network VLAN1 to our guest.

To create a bridge execute the below command:

# brctl addbr br1

Now associate br1 with VLAN1 which is configured on eno1.1

# brctl addif br1 eno1.1

Now, we need to edit the configuration  of our newly created bridge :

# vi /etc/sysconfig/network-scripts/ifcfg-br1






Save and quit

Now, we should associate eno1.1 to  br1

# vi /etc/sysconfig/network-scripts/ifcfg-eno1.1

and we add this line:


So, now it will look like






To apply changes in network configuration, we have to restart network service:

# /etc/init.d/network restart

That’s it, now you have successfully configured VLAN1, follow the same steps for VLAN 2.

Now, all you have to do is to assign br1 as network device to your guest machine and restart the guest machine.

Setting up Virtual user with VSFTPD with Different Permissions

If you want to  setup a virtual user with  VSFTPD and also want to  share the same directory across multiple users then you can refer the below simple steps to achieve this :

  • Install VSFTPD  server
yum install vsftpd
  • Open the /etc/vsftpd/vsftpd.conf file and add the below contents :

save and quit

Here pasv_address= is explicitly used to map the nat IP  to  public IP for passive port

  • Now go  to  directory /etc/vsftpd/vsftpd-virtual-user/ and create the file :: vsftpd_user
    cd /etc/vsftpd/vsftpd-virtual-user/

    Note :: You need to  create the directory : /etc/vsftpd/vsftpd-virtual-user/ if it doesn’t exist

  • In vsftpd_user file add the usernames for which you want to set per user  configuration
[email protected]~[#] cat vsftpd_user
  • Now create the usernames file as ::
[email protected]~[#] cat test

Here, deny_file will limit the access to specific files and folders for user test and same will be used for hiding the files

To use the benefit of share/common directory add the users as ::

First create a group called :  ftp_users

then add the users as ::

useradd -d /home/share-drive -s /sbin/nologin username

Once done that, use the command usermod -G ftp_users test this will facilitates all the files and folders creation with test:ftp_users .

To  add new user use :
 useradd -d /home/share-drive -s /sbin/nologin -g  ftp-users test1

Finally,  restart the VSFTPD service and you are done.


all FTP commands and save it on the system for reference:

# List of FTP commands
# ABOR - Abort an active file transfer.
# ACCT - Account information.
# ADAT - Authentication/Security Data (RFC 2228)
# ALLO - Allocate sufficient disk space to receive a file.
# APPE - Append.
# AUTH - Authentication/Security Mechanism (RFC 2228)
# CCC  - Clear Command Channel (RFC 2228)
# CDUP - Change to Parent Directory.
# CONF - Confidentiality Protection Command (RFC 697)
# CWD  - Change working directory.
# DELE - Delete file.
# ENC  - Privacy Protected Channel (RFC 2228)
# EPRT - Specifies an extended address and port to which the server should connect. (RFC 2428)
# EPSV - Enter extended passive mode. (RFC 2428)
# FEAT - Get the feature list implemented by the server. (RFC 2389)
# HELP - Returns usage documentation on a command if specified, else a general help document is returned.
# LAND - Language Negotiation (RFC 2640)
# LIST - Returns information of a file or directory if specified, else information of the current working directory is returned.
# LPRT - Specifies a long address and port to which the server should connect. (RFC 1639)
# LPSV - Enter long passive mode. (RFC 1639)
# MDTM - Return the last-modified time of a specified file. (RFC 3659)
# MIC  - Integrity Protected Command (RFC 2228)
# MKD  - Make directory.
# MLST - Lists the contents of a directory if a directory is named. (RFC 3659)
# MODE - Sets the transfer mode (Stream, Block, or Compressed).
# NLST - Returns a list of file names in a specified directory.
# NOOP - No operation (dummy packet; used mostly on keepalives).
# OPTS - Select options for a feature. (RFC 2389)
# PASS - Authentication password.
# PASV - Enter passive mode.
# PBSZ - Protection Buffer Size (RFC 2228)
# PORT - Specifies an address and port to which the server should connect.
# PWD  - Print working directory. Returns the current directory of the host.
# QUIT - Disconnect.
# REIN - Re initializes the connection.
# REST - Restart transfer from the specified point.
# RETR - Retrieve (download) a remote file.
# RMD  - Remove a directory.
# RNFR - Rename from.
# RNTO - Rename to.
# SITE - Sends site specific commands to remote server.
# SIZE - Return the size of a file. (RFC 3659)
# SMNT - Mount file structure.
# STAT - Returns the current status.
# STOR - Store (upload) a file.
# STOU - Store file uniquely.
# STRU - Set file transfer structure.
# SYST - Return system type.
# TYPE - Sets the transfer mode (ASCII/Binary).
# USER - Authentication username.