Tip

Sometimes deployment process or other heavy task may cause some Nagios checks to rise below normal levels and bother admin1. If this is expected and you want to add downtime on host/service during this task you may use this script: #!/bin/bash function die { echo $1; exit 1; } if [[ $# -eq 0 ]] ; then die "Give hostname and time in minutes as parameter!" fi if [[ $# -eq 1 ]] ; then MINUTES=15 else MINUTES=$2 fi HOST=$1 NAGURL=http://nagios.example.com/nagios/cgi-bin/cmd.cgi USER=nagiosuser PASS=nagiospassword SERVICENAME=someservice COMMENT="Deploying new code" export MINUTES echo "Scheduling downtime on $HOST for $MINUTES minutes..." # The following is urlencoded already STARTDATE=`date "+%d-%m-%Y %H:%M:%S"` # This gives us the date/time X minutes from now ENDDATE=`date "+%d-%m-%Y %H:%M:%S" -d "$MINUTES min"` curl --silent --show-error \ --data cmd_typ=56 \ --data cmd_mod=2 \ --data host=$HOST \ --data-urlencode "service=$SERVICENAME" \ --data-urlencode "com_data=$COMMENT" \ --data trigger=0 \ --data-urlencode "start_time=$STARTDATE" \ --data-urlencode "end_time=$ENDDATE" \ --data fixed=1 \ --data hours=2 \ --data minutes=0 \ --data btnSubmit=Commit \ --insecure \ $NAGURL -u "$USER:$PASS"| grep -q "Your command request was successfully submitted to Nagios for processing." || die "Failed to con tact nagios"; echo Scheduled downtime on nagios from $STARTDATE to $ENDDATE Threat this script as template with some tips: ...

From the first moment I heard about Let’s Encrypt I liked it and wanted to use it as fast as possible. But the more I read how they want to implement it, the more I dislike it. Current project with automatic configuration is not what I want to use at all. I have many very complicated configs and I do not trust such tools enough to use them. I like UNIX’s single purpose principle, tools should do one thing and do it well - nothing more. ...

Lately I had a lot of brute force attacks on my WordPress blog. I used basic auth to /wp-admin part in nginx configuration to block this and as a better solution I wan’t to block source IPs at all on firewall. To do this, place this filter code in /etc/fail2ban/filter.d/wp-login.conf: # WordPress brute force wp-login.php filter: # # Block IPs trying to authenticate in WordPress blog # # Matches e.g. # 178.218.54.109 - - [31/Dec/2015:10:39:34 +0100] "POST /wp-login.php HTTP/1.1" 401 188 "-" "Mozilla/5.0 (Windows NT 6.0; rv:34.0) Gecko/20100101 Firefox/34.0" # [Definition] failregex = ^<HOST> .* "POST /wp-login.php ignoreregex = Then edit your /etc/fail2ban/jail.local and add: ...

I have some Ansible roles to configure my vps, Raspberry Pi, etc. I like to test them before I broke something on my real, not clustered machines - I use Vagrant for that. But with it I had one problem - in playbooks I define hosts as groups of severs ex. web for my vps: Example Ansible playbook - hosts: web gather_facts: True sudo: True ... But testing machine wasn’t in this group and when I run vagrant I could only see: ...

Normally you want dynamic content to be fresh and not catchable. But sometimes it may be useful to cache it, like when you have website behind reverse proxy. To do this try something like this: <filesmatch "\.(php|cgi|pl)$"> Header unset Pragma Header unset Expires Header set Cache-Control "max-age=3600, public" </filesmatch> Sources http://www.askapache.com/htaccess/speed-up-your-site-with-caching-and-cache-control.html  external link

It will happen from time to time, that you’re on alien machine and have to brutally update things in db without knowing credentials. Example is for root (quite secure candidate to change because it shouldn’t be used in app 😃 ) but will work for any user. shutdown db service mysql stop create text file with command like this (update user accordingly) ex. in /tmp/pwchange.txt SET PASSWORD FOR "root"@"localhost" = PASSWORD("HereYourNewPassword"); start mysqld with --init-file param mysqld_safe --init-file=/tmp/pwchange.txt sometimes you may require to point configuration file ex. --defaults-file=/etc/mysql/my.cnf ...

I hate movies recorded on phone in vertical position. This just short tip how I dealt with with it last time: for m in *.mp4 do avconv -i $m -vf "transpose=1" -codec:a copy -codec:v libx264 -preset slow -crf 23 rotated-$m done Other examples: http://stackoverflow.com/questions/3937387/rotating-videos-with-ffmpeg  external link http://superuser.com/questions/578321/how-to-flip-a-video-180  external link °-vertical-upside-down-with-ffmpeg ...

I had some passwords saved in remmina but like it always happen, I wasn’t been able to remember them when needed. Trying to restore them I found that they’re encrypted in .remmina directory. Then I used this script to decrypt them 1: Extract script import base64 from Crypto.Cipher import DES3 secret = base64.decodestring("<STRING FROM remmina.prefs>") password = base64.decodestring("<STRING FROM XXXXXXX.remmina>") print DES3.new(secret[:24], DES3.MODE_CBC, secret[24:]).decrypt(password) http://askubuntu.com/questions/290824/how-to-extract-saved-password-from-remmina  external link  ↩︎ ...

Allow from IP without password prompt, and also allow from any address with password prompt Order deny,allow Deny from all AuthName "htaccess password prompt" AuthUserFile /web/askapache.com/.htpasswd AuthType Basic Require valid-user Allow from 172.17.10.1 Satisfy Any Sources http://www.askapache.com/htaccess/apache-authentication-in-htaccess.html  external link

When configuring RAID it’s quite important to have the same partition tables on every disk. I’v done this many times on msdos partition tables like this: sfdisk -d /dev/sda | sfdisk /dev/sdb but it’s not working any more on GPT partition tables. Hopefully it still can be done but with different toolstack 😄 Install gdisk: apt-get install -y gdisk Then use sgdisk like this: sgdisk -R /dev/sd_dest /dev/sd_src sgdisk -G /dev/sd_dest First command will copy partition from /dev/sd_src to /dev/sd_dest. Second will randomize partition UUID’s - needed only if you want to use disks in same machine (this is my case). ...