Networks Guru

Month: December 2017

Parsing a list of IPs and/or Networks with Prefix-Length or Subnet Masks

A very simple script that uses ipcalc capabilities to parse a list of IPs or networks an outputs a list of readable Network IDs with their subnet masks.

#!/bin/bash

AUTHOR=AHMED
Blog=”Networks.Guru”

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The Impact of License Expiry on F5 BIG-IP VE

When a license “Support Contract” expires on an F5 appliance whether if it’s a Physical or a Virtual appliance, there’s no effect/disruption to the production environment configured on the device itself.
When the support contract is expired the impact is described below,

– If you come across a software issue or bugs, then you will not be able to upgrade
– No support/assistance will be provided by the vendor related to the appliance.

It’s usually advised to contact the support in case of any doubts.

Changing the Wireless Card’s Transmission Power

The current value of the wireless card’s TX-Power can be verified using the below command

user@pc:~ $ iwconfig
wlan0 IEEE 802.11 ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=22 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on

user@pc:~ $ iw reg get
country GB: DFS-ETSI
(2402 - 2482 @ 40), (N/A, 20), (N/A)
(5170 - 5250 @ 80), (N/A, 20), (N/A)
(5250 - 5330 @ 80), (N/A, 20), (0 ms), DFS
(5490 - 5710 @ 160), (N/A, 27), (0 ms), DFS
(57000 - 66000 @ 2160), (N/A, 40), (N/A)

The Tx-Power value is in dBm “Decibel (referenced to milliwatts)” This value can be converted to milliwatts using this function

P(mW) = 1mW ⋅ 10(P(dBm)/ 10)

Before changing the value of the Tx-Power, You need to make sure that you comply with the legal limits within your country and you’ll not end up frying the wireless card

The below commands can be used to change the current value of the transmission power

The max value cannot be set over the limit specified by the assigned country’s regulations

So, for education Purpose only the country may be set to a country allowing higher Transmission power “ex: Bolivia <BO>”

 

ifconfig wlan0 down
iw reg set BO
ifconfig wlan0 up
iwconfig wlan0 txpower 30

 

So,  By verifying the results of the last commands, we see that the values have been set successfully

user@pc:~ $ iwconfig wlan0
wlan0 IEEE 802.11 ESSID:off/any
Mode:Managed Access Point: Not-Associated Tx-Power=30 dBm
Retry short limit:7 RTS thr:off Fragment thr:off
Power Management:on

user@pc:~ $ iw reg get
country BO: DFS-JP
(2402 - 2482 @ 40), (N/A, 20), (N/A)
(5250 - 5330 @ 80), (N/A, 30), (0 ms), DFS
(5735 - 5835 @ 80), (N/A, 30), (N/A)

 

 

 

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