How To Block Email Using Subject Headers In Postfix

Author: erics, December 7th, 2021

I needed to block email based on the Subject header. The solution is simple: Edit main.cf as root and uncomment or add:

header_checks = regexp:/etc/postfix/header_checks

1	header_checks = regexp:/etc/postfix/header_checks

Next, creaate or edit /etc/postfix/header_checks as root and add the following line:

/subject:\sbad subject text here/        REJECT  header_checks NO SPAM ALLOWED
/subject:\stest subject text here/        DISCARD  header_checks NO SPAM ALLOWED

1 2	/subject:\sbad subject text here/ REJECT header_checks NO SPAM ALLOWED /subject:\stest subject text here/ DISCARD header_checks NO SPAM ALLOWED

Finally, run sudo postfix reload NOTE: Do NOT add the “i” after the regular expression! It is case-insensitive by […]

Categories: How-To's, Technology Tags: Block, Check, Checks, Discard, Header, header_checks, headers, howto, PostFix, Reject, Spam, Subject, tips | No comments

How To Install/Update CPAN on MacOS Mojave with fatal error: ‘EXTERN.h’ file not found

Author: erics, June 12th, 2019

The Problem Tried to install the latest version of cpan and got stuck. Tracked it down to the dependency module Mac::SystemDirectory which was failing to build:

cpan[1]> install Mac::SystemDirectory                                                                                                                                                                                                                                                    
Reading '/var/root/.cpan/Metadata'
  Database was generated on Sun, 09 Jun 2019 07:17:02 GMT
Running install for module 'Mac::SystemDirectory'
Running make for E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz
Checksum for /var/root/.cpan/sources/authors/id/E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz ok
Scanning cache /var/root/.cpan/build for sizes
............................................................................DONE

  CPAN.pm: Building E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz

HASCOMPILEREZFt/TESTUSSI.c:2:10: fatal error: 'EXTERN.h' file not found
#include "EXTERN.h"
         ^~~~~~~~~~
1 error generated.
Couldn't execute cc  -g -pipe -fno-common -DPERL_DARWIN -fno-strict-aliasing -fstack-protector -Os "-I/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE"   -c HASCOMPILEREZFt/TESTUSSI.c -o HASCOMPILEREZFt/TESTUSSI.o: Inappropriate ioctl for device at Makefile.PL line 14.
Requires a compiler
Warning: No success on command[/usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE]
  ETHER/Mac-SystemDirectory-0.10.tar.gz
  /usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE -- NOT OK
Running make test
  Make had some problems, won't test
Running make install
  Make had some problems, won't install
Failed during this command:
 ETHER/Mac-SystemDirectory-0.10.tar.gz        : writemakefile NO '/usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE' returned status 6400

cpan[1]> install Mac::SystemDirectory

Reading '/var/root/.cpan/Metadata'

Database was generated on Sun, 09 Jun 2019 07:17:02 GMT

Running install for module 'Mac::SystemDirectory'

Running make for E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz

Checksum for /var/root/.cpan/sources/authors/id/E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz ok

Scanning cache /var/root/.cpan/build for sizes

............................................................................DONE

CPAN.pm: Building E/ET/ETHER/Mac-SystemDirectory-0.10.tar.gz

HASCOMPILEREZFt/TESTUSSI.c:2:10: fatal error: 'EXTERN.h' file not found

#include "EXTERN.h"

^~~~~~~~~~

1 error generated.

Couldn't execute cc -g -pipe -fno-common -DPERL_DARWIN -fno-strict-aliasing -fstack-protector -Os "-I/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE" -c HASCOMPILEREZFt/TESTUSSI.c -o HASCOMPILEREZFt/TESTUSSI.o: Inappropriate ioctl for device at Makefile.PL line 14.

Requires a compiler

Warning: No success on command[/usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE]

ETHER/Mac-SystemDirectory-0.10.tar.gz

/usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE -- NOT OK

Running make test

Make had some problems, won't test

Running make install

Make had some problems, won't install

Failed during this command:

ETHER/Mac-SystemDirectory-0.10.tar.gz : writemakefile NO '/usr/bin/perl Makefile.PL INC=-I/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk/System/Library/Perl/5.18/darwin-thread-multi-2level/CORE' returned status 6400

The Solution Use the MacOS installer command to deploy the needed files:

xcode-select --install
sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /
installer: Package name is macOS_SDK_headers_for_macOS_10.14
installer: Installing at base path /
installer: The install was successful.

xcode-select --install

sudo installer -pkg /Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg -target /

installer: Package name is macOS_SDK_headers_for_macOS_10.14

installer: Installing at base path /

installer: The install was successful.

The, rerunning the cpan install works:

cpan[1]> install Mac::SystemDirectory                                                                                                                                                                                                                                                    
...
Running make install
Files found in blib/arch: installing files in blib/lib into architecture dependent library tree
Installing /Library/Perl/5.18/darwin-thread-multi-2level/auto/Mac/SystemDirectory/SystemDirectory.bs
Installing /Library/Perl/5.18/darwin-thread-multi-2level/auto/Mac/SystemDirectory/SystemDirectory.bundle
Installing /Library/Perl/5.18/darwin-thread-multi-2level/Mac/SystemDirectory.pm
Installing /usr/local/share/man/man3/Mac::SystemDirectory.3pm
Appending installation info to /Library/Perl/Updates/5.18.2/darwin-thread-multi-2level/perllocal.pod
  ETHER/Mac-SystemDirectory-0.10.tar.gz
  /usr/bin/make install  -- OK

cpan[1]> install Mac::SystemDirectory

...

Running make install

Files found in blib/arch: installing files in blib/lib into architecture dependent library tree

Installing /Library/Perl/5.18/darwin-thread-multi-2level/auto/Mac/SystemDirectory/SystemDirectory.bs

Installing /Library/Perl/5.18/darwin-thread-multi-2level/auto/Mac/SystemDirectory/SystemDirectory.bundle

Installing /Library/Perl/5.18/darwin-thread-multi-2level/Mac/SystemDirectory.pm

Installing /usr/local/share/man/man3/Mac::SystemDirectory.3pm

Appending installation info to /Library/Perl/Updates/5.18.2/darwin-thread-multi-2level/perllocal.pod

ETHER/Mac-SystemDirectory-0.10.tar.gz

/usr/bin/make install -- OK

Categories: How-To's, Technology Tags: 10.14, CPAN, Error, extern.h, Fatal, Fatal Error, File not found, Header, headers, howto, Install, installer, Libraries, Library, MacOS, Mojave, not found, Package, perl, pkg, System, tips, update, upgrade, XCode | No comments

How To Allow Cross-Site Javascript Using Apache

Author: erics, September 24th, 2015

The key is to send a response header like this: Access-Control-Allow-Origin: * In the Apache web server, one enables this via the following directive: Header set Access-Control-Allow-Origin * This requires the use of mod_headers, which is enabled by default in Apache. For example:

LoadModule headers_module modules/mod_headers.so
...
<VirtualHost *:80>
    ServerName www.your.domain
    ServerAlias *your.domain
    DocumentRoot /var/www/yourdomain
    DirectoryIndex index.php index.html
    Header set Access-Control-Allow-Origin *
</VirtualHost>

LoadModule headers_module modules/mod_headers.so

...

ServerName www.your.domain

ServerAlias *your.domain

DocumentRoot /var/www/yourdomain

DirectoryIndex index.php index.html

Header set Access-Control-Allow-Origin *

</VirtualHost>

Categories: How-To's, Technology Tags: Access-Control-Allow-Origin, ajax, apache, cross, cross-site, cross-site javascript, headers, howto, http, javascript, Load, mod_headers, tips, xsite | No comments

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How To Block Email Using Subject Headers In Postfix

How To Install/Update CPAN on MacOS Mojave with fatal error: ‘EXTERN.h’ file not found

How To Allow Cross-Site Javascript Using Apache

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