[resolved]iwconfig not running as before on TP-Link 841N v9

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numerci
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Joined: 02 May 2012
Posts: 74

PostPosted: Tue Sep 12, 2017 18:02    Post subject: [resolved]iwconfig not running as before on TP-Link 841N v9 Reply with quote
On my TP-Link 841N v9 I used to have some cron scripts to lower the WiFi power during the night when I do not need it to be at full power:

00 22 * * * root iwconfig ath0 txpower 5
00 07 * * * root iwconfig ath0 txpower 20

This has used to work fine till the 33xxx versions. Also still works well on Archer C7 on builds 33xxx, but not with 841N.

I do not think that the cron jobs are at fault but the commands are not accepted anymore. If I try to run them from the run command the following error is displayed:

Command: iwconfig ath0 txpower 5
Error: sh: eval: line 1: iwconfig: not found

Any hints how to get around this error?


Last edited by numerci on Thu Sep 14, 2017 17:16; edited 2 times in total
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mwchang
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Joined: 26 Mar 2013
Posts: 138
Location: Hung Hom, Hong Kong

PostPosted: Wed Sep 13, 2017 14:27    Post subject: Re: Cron scripts not running as before Reply with quote
numerci wrote:
...
00 22 * * * root iwconfig ath0 txpower 5
00 07 * * * root iwconfig ath0 txpower 20
....
I do not think that the cron jobs are at fault but the commands are not accepted anymore. If I try to run them from the run command the following error is displayed:

Command: iwconfig ath0 txpower 5
Error: sh: eval: line 1: iwconfig: not found

Any hints how to get around this error?

Try specifying full path to iwconfig, for example,
Code:
00 22 * * * root /sbin/iwconfig ath0 txpower 5

A Google search (keywords: "iwconfig not found") result that might interest you:
https://www.reddit.com/r/debian/comments/3eadkg/wirelesstools_installed_iwconfig_not_found/

_________________
Router: Asus RT-N18U

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numerci
DD-WRT User


Joined: 02 May 2012
Posts: 74

PostPosted: Wed Sep 13, 2017 16:00    Post subject: Reply with quote
Thanks for the hint but this does not help. There is still the same message:

DD-WRT v3.0-r33006 std (c) 2017 NewMedia-NET GmbH
Release: 08/03/17

DD-WRT login: root
Password:
==========================================================

___ ___ _ _____ ______ ____ ___
/ _ \/ _ \___| | /| / / _ \/_ __/ _ __|_ / / _ \
/ // / // /___/ |/ |/ / , _/ / / | |/ //_ <_/ // /
/____/____/ |__/|__/_/|_| /_/ |___/____(_)___/

DD-WRT v3.0
http://www.dd-wrt.com

==========================================================


BusyBox v1.27.1 (2017-08-03 05:02:44 CEST) built-in shell (ash)

root@DD-WRT:~# /sbin/iwconfig ath0 txpower 5
-sh: /sbin/iwconfig: not found
root@DD-WRT:~#


I am afraid that not the entire Wireless tools package is installed anymore on this router. Could be that they have tried to save the space.
mwchang
DD-WRT User


Joined: 26 Mar 2013
Posts: 138
Location: Hung Hom, Hong Kong

PostPosted: Wed Sep 13, 2017 16:17    Post subject: Reply with quote
numerci wrote:
Thanks for the hint but this does not help. There is still the same message:
....
Code:
BusyBox v1.27.1 (2017-08-03 05:02:44 CEST) built-in shell (ash)

root@DD-WRT:~# /sbin/iwconfig ath0 txpower 5
-sh: /sbin/iwconfig: not found
root@DD-WRT:~#


I am afraid that not the entire Wireless tools package is installed anymore on this router. Could be that they have tried to save the space.

Maybe iwconfig was deprecated?? Google-d "iwconfig replacement" and this result looks interesting:

https://dougvitale.wordpress.com/2011/12/21/deprecated-linux-networking-commands-and-their-replacements/

_________________
Router: Asus RT-N18U

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numerci
DD-WRT User


Joined: 02 May 2012
Posts: 74

PostPosted: Wed Sep 13, 2017 16:20    Post subject: Reply with quote
Ok, it seem that iwconfig command is deprecated and was replaced by iw. On this command the router seem to respond but I need to see how it can be correctly used.
mwchang
DD-WRT User


Joined: 26 Mar 2013
Posts: 138
Location: Hung Hom, Hong Kong

PostPosted: Wed Sep 13, 2017 16:21    Post subject: Reply with quote
numerci wrote:
Ok, it seem that iwconfig command is deprecated and was replaced by iw. On this command the router seem to respond but I need to see how it can be correctly used.

Glad to know it helps.

BTW, some Linux distributions might put iwconifg in directories other than /sbin. So don't just assume the locations of certain commands. Search for it using find or ls.

_________________
Router: Asus RT-N18U

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numerci
DD-WRT User


Joined: 02 May 2012
Posts: 74

PostPosted: Wed Sep 13, 2017 17:49    Post subject: Reply with quote
For iw these would be the options:

Setting TX power

You can set the txpower by using either the device interface name of the respective phy.

iw dev <devname> set txpower <auto|fixed|limit> [<tx power in mBm>]
iw phy <phyname> set txpower <auto|fixed|limit> [<tx power in mBm>]
(Note that the value this commands takes is in millibel-milliwatts (mBm) instead of the commonly used decibel-milliwatts (dBm). <power in mBm> = 100 * <power in dBm>)


The command was accepted but has not changed anythig.

iw dev ath0 set txpower fixed [500]

Maybe I have misunderstood the 500 value.
mwchang
DD-WRT User


Joined: 26 Mar 2013
Posts: 138
Location: Hung Hom, Hong Kong

PostPosted: Wed Sep 13, 2017 19:48    Post subject: Reply with quote
numerci wrote:
For iw these would be the options:

Setting TX power

You can set the txpower by using either the device interface name of the respective phy.

iw dev <devname> set txpower <auto|fixed|limit> [<tx power in mBm>]
iw phy <phyname> set txpower <auto|fixed|limit> [<tx power in mBm>]
(Note that the value this commands takes is in millibel-milliwatts (mBm) instead of the commonly used decibel-milliwatts (dBm). <power in mBm> = 100 * <power in dBm>)


The command was accepted but has not changed anythig.

iw dev ath0 set txpower fixed [500]

Maybe I have misunderstood the 500 value.

Or maybe DD-WRT doesn't understand iw but iwconfig? Need expert opinions! Smile

BTW, you might wanna update the subject of your post. It's no longer about cron but iwconfig!

_________________
Router: Asus RT-N18U

May the Force and farces be with you! Live long and proper!

Facebook: https://zh-hk.facebook.com/changmanwai
Website: https://sites.google.com/site/changmw
SETI@Home profile: http://setiathome.berkeley.edu/view_profile.php?userid=211832
numerci
DD-WRT User


Joined: 02 May 2012
Posts: 74

PostPosted: Wed Sep 13, 2017 20:04    Post subject: Reply with quote
It used to work fine with iwconfig on TP_link 841N v9 and it still works fine on Archer C7 v2. Is not a big issue but would be nice to have this working again.

Problem is that I do not understand what is wrong.

PS: the subject of the thread was updated.
numerci
DD-WRT User


Joined: 02 May 2012
Posts: 74

PostPosted: Thu Sep 14, 2017 17:05    Post subject: Reply with quote
Problem solved!

Old entry that was needed on the Cron jobs that is not working anymore:
00 22 * * * root iwconfig ath0 txpower 5
00 07 * * * root iwconfig ath0 txpower 20

Needs to be replaced with:
00 22 * * * root iw dev ath0 set txpower fixed 500
00 07 * * * root iw dev ath0 set txpower fixed 2000

And it works as before. Smile
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