Blocking social networks on Cisco

On the test I use the Cisco Catalyst 6509-E switch.
Suppose we need to block access to users to a certain site, a network node, or for example a social network VKontakte.

First, we know the range of IP addresses on which the site is located, for example, we search VKontakte on, here is for example the list of subnets for one of the AS belonging to VKontakte “”.

And create an extended ACL for example with the name BLOCKSOCIAL:

ip access-list extended BLOCKSOCIAL
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
permit ip any any

The rule above indicates that you want to block traffic to the specified networks coming from all (any) sources.
You can specify as a source a specific network or for example one address to deny access to another address:

deny ip host host

The line “permit ip any any” should be necessary at the end.

Instead of a subnet mask, you need to specify the Wildcard, for example, for the mask /24, specify, for /22 –, etc., you can look at and count on any IP calculator.
/17 –
/18 –
/19 –
/20 –
/21 –
/22 –
/23 –
/24 –

If you want to block more sites, we’ll add the addresses to the same ACL, since only one can be applied to the ACL interface.

Apply the created ACL to the port looking towards the clients:

interface GigabitEthernet1/1
ip access-group BLOCKSOCIAL in

Or, to write less only to the server’s server port on the Internet, if there is one:

interface TenGigabitEthernet3/2
ip access-group BLOCKSOCIAL in

You can cancel the ACL interface as follows:

no ip access-group BLOCKSOCIAL in

Delete the ACL like this:

no ip access-list extended BLOCKSOCIAL

If you block sites on the port from the server to the clients, then in the ACL rule we will change the addresses in the following places:

ip access-list extended BLOCKSOCIAL
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
deny ip any
deny ip host any
permit ip any any

See also my articles:
Blocking social networks on Mikrotik routers
Blocking social networks using iptables

How to convert audio files to ulaw, alaw, gsm, g722, etc. for Asterisk

After ordering the voice acting from a professional announcer and cutting in the sound editor, it was necessary to save the sounds in different formats, the original was in wav, so I’ll give an example of converting through sox (it already was in the system with Asterisk):

sox -V vm-intro.wav -r 8000 -c 1 -t ul vm-intro.ulaw
sox -V vm-intro.wav -r 8000 -c 1 -t al vm-intro.alaw
sox -V vm-intro.wav -r 8000 -c 1 -t gsm vm-intro.gsm

The codec g722 does not seem to support it, at least in man sox did not find it, so it installed ffmpeg (on the Ubuntu Server system):

sudo apt-get install ffmpeg

And performed the conversion:

ffmpeg -i vm-intro.wav -ar 16000 -acodec g722 vm-intro.g722

Standard directory with Asterisk sounds – /usr/share/asterisk/sounds

The solution to the error “Virtual machine could not be started because the hypervisor is not running”

I noticed once on one HP server, after installing Hyper-V, that virtual workstations are not being launched, giving the following error:

Hyper-V Manager
An error occurred while attempting to start the selected virtual machine(s).

Virtual machine could not be started because the hypervisor is not running.

As it turned out, the problem was in the Intel (R) Virualization Tech not activated in BIOS, after changing from “Disabled” to “Enabled” and start the system, the virtual workstations were successfully launched.

Backup configuration of TP-Link switches

I wrote a script for backup configuration of TP-Link switches.
The script runs on Linux where the TFTP server is running, it is connected via telnet to the switch and the configuration command is sent to the specified TFTP, when the telnet connection is closed, the file is moved to the desired directory, and the last command deletes files longer than 30 days, as more of them I do not need to store.
You can also make a copy of all the files in the cloud every month.
As you can see, before entering a password in the script, you can not pause.

echo "PASSWORD";
echo "enable";
echo "PASSWORD";
echo "copy startup-config tftp ip-address filename tplink";
sleep 2;
echo "exit";
sleep 1;
echo "exit";
} | telnet

mv /srv/tftp/tplink.cfg /backups/devices/tplink/`date +%Y-%m-%d`_tplink.cfg
find /backups/devices/tplink/ -type f -mtime +30 -exec rm {} \;

The reboot script of Wi-Fi routers TP-Link

Below is an example of the TP-Link router reboot script, I will test it on TL-WR720N 2.0 from Ubuntu Server.


# exit if router is down
ping -q -c 1 "$ROUTER_IP" > /dev/null || exit

curl --basic --user "$USERNAME:$PASSWORD" -A "Mozilla/4.73 [en] (X11; U; Linux 2.2.15 i686)" --refer "http://$ROUTER_IP" "$ROUTER_IP/userRpm/SysRebootRpm.htm?Reboot=reboot"

The contents of the script will be placed in a new file, for example, using the nano editor (“CTRL+X” to exit and “y” to save the changes):


And make it executable:

chmod 777

After this, we execute:


Similarly, you can perform other functions instead of rebooting.