Tuesday, March 11, 2014

Certificate for courier esmtpd

To enable SSL/TLS support for the ESMTP, you need to have a server certificate. Usually, the installation process of the package in a Linux distribution will create a default, self-signed certificate for you. However, if you want to create a proper certificate for your site, following is some simple steps to do so.

First, you need to generate a key for your server if you don't already have one:
openssl genrsa -out server.key 2048
With that key, you can then generate a certificate request:
openssl req -new -key server.key -out server.csr
If you did not customize your openssl.cnf configuration file, the above command will prompt you for the details of identify for the server in the certificate. Answer all questions as you please except for the common name "CN", which should be the host name to connect to your server.

Now, you need to get a Certificate Authority to sign your request. For example, if you have a demoCA setup for your openssl installation, you can do:
openssl ca -config openssl.cnf -policy policy_anything -out server.crt -infiles server.csr
This results in the certificate file server.crt. You then can combine the server key and certificate files to create the certificate file for the courier mail server.
cat server.key server.crt > esmtpd.pem
This used to be sufficient. However, the newer version (0.73) of courier requires a "DH parameters" block in the certificate file. This can be generated and appended with:
openssl dhparam 1024 >> esmtpd.pem
Now, you can point the "TLS_CERTFILE" in all the configuration files to the certificate esmtpd.pem and restart your server.

Tuesday, January 7, 2014

Example: data preprocessing with BASH

Case situation

I have run some batch jobs on a cluster to process data files for different systems (msc, ms, sh, rd) and parameters (i and w). The files are in different subdirectories:
[cjj@gust pattern]$ ls d-*/*.spd
d-msc/i275w042526.spd  d-ms/i285w025017.spd  d-rd/i295w042812.spd
d-msc/i280w040241.spd  d-ms/i290w023034.spd  d-sh/i275w051138.spd
d-msc/i285w036791.spd  d-ms/i295w020787.spd  d-sh/i280w047315.spd
d-msc/i290w031925.spd  d-rd/i270w065151.spd  d-sh/i285w043415.spd
d-msc/i295w026791.spd  d-rd/i275w060475.spd  d-sh/i290w039589.spd
d-ms/i270w034433.spd   d-rd/i280w055777.spd  d-sh/i295w035791.spd
d-ms/i275w030644.spd   d-rd/i285w051257.spd
d-ms/i280w027133.spd   d-rd/i290w046948.spd
[cjj@gust pattern]$
While, the output files are in the current directory:
[cjj@gust pattern]$ ls *.o*
i270w034433.spd.o172489  i275w060475.spd.o172496  i285w036791.spd.o172486
i270w065151.spd.o172495  i280w027133.spd.o172491  i290w023034.spd.o172493
i275w030644.spd.o172490  i280w040241.spd.o172485  i290w031925.spd.o172487
i275w042526.spd.o172484  i285w025017.spd.o172492  i295w026791.spd.o172488
[cjj@gust pattern]$
The format of the output log files are as follows:
[cjj@gust pattern]$ cat i270w034433.spd.o172489
MinTemplateNumber =  3
JT =  5
JN =  1
spikeResolution =  2
Number of initial spike patterns have been found : 562
ans = Creating surrogate data
ans = Creating time jittering surrogate data
ans = Creating neuron jittering surrogate data
Number of spike patterns have been valid by checking with sorrogate : 542
Number of spike patterns have been ruled out because of having less complex : 205
Number of valid spike patterns have been found : 337
[cjj@gust pattern]$

Problem task

Gather the stats in the log files as those marked in red.

Solution 1

This is done with a one-liner:
[cjj@gust pattern]$ for i in d-*/*.spd;do n=${i%/*};n=${n#d-};s=${i#*/};if [ -f ${s}.o* ];then w=${s%.spd};w=${w#*w}; echo ${n} ${s:1:2}.${s:3:1} $((1${w:0:2}-100)).${w:2} `grep ':' ${s}.o* | awk '{print $NF}'`;fi;done > matching_stat.txt
which can be broken down to:
for i in d-*/*.spd;do
  if [ -f ${s}.o* ];then
    echo ${n} ${s:1:2}.${s:3:1} $((1${w:0:2}-100)).${w:2} `grep ':' ${s}.o* | awk '{print $NF}'`
done > matching_stat.txt
The data file generated is:
[cjj@gust pattern]$ cat matching_stat.txt 
msc 27.5 4.2526 81 75 22 53
msc 28.0 4.0241 237 217 103 114
msc 28.5 3.6791 393 371 156 215
msc 29.0 3.1925 335 322 132 190
msc 29.5 2.6791 445 437 144 293
ms 27.0 3.4433 562 542 205 337
ms 27.5 3.0644 1037 1006 331 675
ms 28.0 2.7133 1141 1093 341 752
ms 28.5 2.5017 1325 1274 462 812
ms 29.0 2.3034 1652 1609 747 862
rd 27.0 6.5151 1031 953 313 640
rd 27.5 6.0475 1042 963 345 618
[cjj@gust pattern]$