CRDA(8) Linux CRDA(8)
NAME
crda - send to the kernel a wireless regulatory domain for a given ISO / IEC 3166 alpha2
SYNOPSIS
crda
Description
crda is the Linux wireless central regulatory domain agent. crda is intended to be used
by udev scripts and should not be run manually unless debugging udev scripts. crda is
triggered to run by the kernel by sending a udev event upon a new regulatory domain
change. Regulatory domain changes are triggered by the wireless kernel subsystem (upon
initialization and on reception of country IEs), wireless drivers, or userspace (see iw ).
Upon a regulatory domain change the kernel sends a udev change event for the regulatory
platform. The kernel ignores regulatory domains sent to it if it does not expect them. The
regulatory domain is read by crda from the regulatory.bin file.
RSA Digital Signature
If built with openssl or gcrypt support crda will have embedded into it an RSA digital
signature which will prevent it from reading corrupted or non-authored regulatory.bin
files. Authorship is respected by the RSA public key packed into crda. This specific crda
package has been built with an RSA public key from John Linville (the Linux wireless ker‐
nel maintainer) and as such will only read regulatory.bin files signed by him. For further
information see the regulatory.bin man page.
UDEV RULE
A udev regulatory rule must be put in place in order to receive and parse udev events from
the kernel in order to get udev to call crda with the passed ISO / IEC 3166 alpha2 country
code. An example udev rule which can be used (usually in /lib/udev/rules.d/85-regula‐
tory.rules ):
KERNEL=="regulatory*", ACTION=="change", SUBSYSTEM=="platform", RUN+="/sbin/crda"
Environment variable
Set the COUNTRY environment variable with a specific ISO / IEC 3166 alpha2 country code
and then run crda without arguments. This will send a regulatory domain for that alpha2 to
the kernel.
SEE ALSO
iw(8) regulatory.bin(5)
http://wireless.kernel.org/en/developers/Regulatory/
crda 23 January 2009 CRDA(8)
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