https://tech.snathan.org/ 2026-04-14T11:34:49+00:00 https://tech.snathan.org/ https://tech.snathan.org/_media/wiki/dokuwiki.svg text/html 2017-12-20T12:26:18+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/account_locked?rev=1513772778&do=diff Redhat Account locked If the Linux user account is locked in Redhat, a brute way to remove the lock for all accounts is: cat /dev/null > /var/log/faillog Keywords: password failed login attempts text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/adodb?rev=1416064423&do=diff adodb on home unbuntu server FIXME When installing some app (I believe it was mantis) got the following warning: libphp-adodb is no longer installed in /usr/share/adodb. New installation path is now /usr/share/php/adodb. Please update your php.ini file. Maybe you must also change your web-server configuraton. text/html 2022-02-13T12:28:45+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/apache_configuration?rev=1644755325&do=diff Apache Configuration (Ubuntu 18.04 Bionic Beaver) Enable the below /usr/sbin/a2enmod headers rewrite socache_shmcb /etc/apache2/apache2.conf Original vs Modified (Original < and Modified >) 175a176,181 > <Directory /data/www/> > Options Indexes FollowSymLinks > AllowOverride None > Require all granted > </Directory> > 213a220 > LogFormat "%{X-Forwarded-For}i %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" proxycomb 216a224,227 > LogFormat "%h %t %>s %B %D %k"… text/html 2020-01-27T12:27:27+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/apache_old_config?rev=1580128047&do=diff Apache Configuration (Ubuntu 12.04 Precise Pangolin) Apache configuration for Ubuntu are at /etc/apache2 httpd.conf file is an empty file by default. Update as, Where xxxxxx is the short unqualified host name such as abc01 ServerName xxxxxx ExtendedStatus On text/html 2020-01-26T12:27:29+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/apt_update_resource_overload?rev=1580041649&do=diff Disable updates (Bionic) systemctl disable apt-daily.timer systemctl disable apt-daily-upgrade.timer APT update resource overload apt has a daily and weekly update on Ubuntu servers. On servers with limited CPU and Memory this could pose an issue. If the servers are inside the firewall and do not require any updates, security or otherwise, it helps to disable this. text/html 2020-06-21T11:27:33+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/apt_upgrades?rev=1592738853&do=diff Automatic apt upgrades Recently noticed the following on my daily cron output: /etc/cron.daily/apt: Package 'mysql-common' has conffile prompt and needs to be upgraded manually It turns out automatic upgrade of packages is turned on by default in Ubuntu LTS 12.04 Precise Pangolin!!! text/html 2017-12-03T12:26:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/aptitude_undo?rev=1512304013&do=diff Aptitude Undo Operation While in the Aptitude interactive mode, what can you do to undo an accidentally operation. For e.g. a press of the minus key on a large package group! Aptitude does now allow you do perform a mass undo of the action you just initiated. To undo do the following: text/html 2018-09-10T11:27:46+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/backup_directory_script?rev=1536578866&do=diff Bash script to backup Directory Bash script to backup regular files in current directory. The default backup directory is archive inside the current directory. Or you may specify a backup directory as the 1st argument to the script. #!/bin/bash # # Backup Regular files to archive/timestamp # NOW=$(date +"%Y-%m-%d-%H-%M-%S") # # if [[ -z $1 ]] then BACKUPDIR=archive/$NOW else BACKUPDIR=$1/$NOW fi mkdir -p $BACKUPDIR # for file in $(ls -p | grep -v /$) do cp -p $file $BACKUPDIR/ done… text/html 2015-06-24T11:55:38+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/bash_commands?rev=1435146938&do=diff Advanced bash scripting <http://www.tldp.org/LDP/abs/html/index.html> Bash Commands Finding a size of a file file_size=$(stat -c%s "$FILENAME") Wait for user to strike a key read -p "Press [Enter] key to start backup..." Filename from Filepath Extracting File Name with extension and without extension given full file path text/html 2015-04-09T11:46:34+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/bash_date?rev=1428579994&do=diff Date formatting in bash shell #!/bin/bash TS=$(date +%Y%m%d_%H%M%S); # if [[ ! ("$#" == 1) ]]; then echo "Usage for $0 : <xxxxxx> required as argument." exit 1 fi text/html 2020-09-29T11:27:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/bash_loops?rev=1601378863&do=diff bash loops while counter #!/bin/bash # SLEEPTIME=5 MAXCOUNT=5 URL="https://www.example.com/xys" # COUNTER=0 while [ $COUNTER -lt $MAXCOUNT ]; do let COUNTER=COUNTER+1 echo "Iteration: $COUNTER " curl -k $URL echo " Status: $? " # Don't execute for last iteration if [ $COUNTER -lt $MAXCOUNT ]; then sleep $SLEEPTIME fi done text/html 2022-12-26T12:29:19+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/bash_script_skeleton?rev=1672057759&do=diff Bash Script Skeleton Getting Script Directory SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd ) Processing Arguments and Help function help { echo "Usage: $0 <domain> <acme-string> [type] [name]" echo "Pass both type and name or neither." echo "Default: type=TXT and name=_acme-challenge" echo echo "E.g.:" echo "Setting a TXT record for _acme-challenge:" } if [ "$#" -lt 2 ]; then help exit 1 else domain=$1 acme=$2 fi if [ "$#" -eq 3 ]; the… text/html 2019-08-11T11:26:57+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/bionic?rev=1565522817&do=diff Notes about Bionic Beaver, Ubuntu LTS 18.01 Disable cloud-init sudo touch /etc/cloud/cloud-init.disabled sudo echo "network: {config: disabled}" > /etc/cloud/cloud.cfg.d/99-disable-network-config.cfg Also update this FCheck for the existence of /etc/cloud/cloud.cfg configuration. If the file exists edit the file and change the settings within: FROM: preserve_hostname: false TO: preserve_hostname: true text/html 2014-12-05T12:43:39+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/build_add_raid?rev=1417783419&do=diff Building an additional raid My box already had two hard disks in raid10. Wanted to add two more disks in a second raid. Here is what I did. This was on Ubuntu Trusty. * Boot with Ubuntu install CD * Go into recover mode * Navigate until you hit the partition disk option (had to go forward and backward in the wizard to end up here!) text/html 2015-06-09T11:43:41+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/check_disk?rev=1433850221&do=diff Check Linux Disk / Filesystem The below will use e2fsck to check with the options of * Use badblocks ( c ) * force check, even if system seems clean (f) * Optimize directories in filesystem (D) * Automatically repair (“preen”) the file system (p) text/html 2015-02-10T12:51:13+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/check_swap?rev=1423572673&do=diff Check pswpin and pswpout Script to check pswpin and pswpout for non-zero values and log/email. #!/bin/bash cd /home/senthil/temp_files/pswp TS=$(date +%Y%m%d_%H%M%S); cat /proc/vmstat|grep pswp > log/pswp_${TS}.txt PSZ=`grep -c "^pswpin 0$" log/pswp_${TS}.txt` if [ $PSZ -eq 0 ]; then cat log/pswp_${TS}.txt | mailx -s "Non-zero pswpin" system@example.org fi text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/chmod_on_directories?rev=1416064423&do=diff Use this example to chmod only directories ls -R <path to some directory> |grep ":$"|sed 's/:$//'|xargs chmod g+x ls -R <path to some directory> |grep ":$"|sed 's/:$//'|xargs chmod o+x text/html 2021-12-06T12:28:39+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/commands_to_add_users_and_groups?rev=1638793719&do=diff Linux Users and Groups Commands Simple Example useradd user007 -m -s /bin/bash passwd user007 adduser user007 www-data Adding Group Adding group someusername with a specific gid of 5001 groupadd -g 5001 someusername Adding User Addding user someusername with a specific id, assign to gid 5001, etc text/html 2020-12-16T12:28:05+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/cpu_usage?rev=1608121685&do=diff CPU Usage Top Processes with CPU usage - alternative to top ps -eo pid,ppid,cmd,%mem,%cpu --sort=-%cpu | head text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/creating_wordpress_websites_on_ub1?rev=1416064423&do=diff Creating WordPress Websites This is different from creating wordpress websites in general. Why? Because this is a single install with single database (a set of tables for each website) approach. This reduces the number of installs and locations and keeps maintenance simple across all wordpress websites. There is a different application for wordpress farm that does this - however I am making my own cup of tea here because I like it that way. text/html 2014-12-03T12:36:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/cron?rev=1417610213&do=diff Crontab Check all Cron As root, to check all crontabs #!/bin/bash cat /etc/crontab cat /etc/cron.d/* cat /etc/cron.daily/* cat /etc/cron.hourly/* cat /etc/cron.monthly/* cat /etc/cron.weekly/* cat /var/spool/cron/crontabs/* text/html 2025-01-27T12:28:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/debian_release_upgrade?rev=1737980929&do=diff Upgrading Debian to a new release These are the steps to upgrade from Bullseye to Bookworm. # Regenerate SSH Kyes /bin/rm /etc/ssh/ssh_host_* /sbin/dpkg-reconfigure openssh-server # # Uninstall VirtualBox Guest Additions /opt/VBoxGuestAdditions-*/uninstall.sh # # Perform the upgrade aptitude unhold linux-image-amd64 aptitude update aptitude upgrade aptitude full-upgrade reboot aptitude update aptitude full-upgrade cat /etc/os-release > ~/before-uprade-os-release.txt hostnamectl # # Release up… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/delete_files_but_not_directories?rev=1416064423&do=diff Command to delete files but not directories (folders) find . -type f -exec rm {} \; -print ---------- Keyword: Unix, Linux, ubuntu text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/delete_files_using_find?rev=1416064423&do=diff Deleting files with a certain extension across directories This will delete all *.txt.gzip files find . -name “*.txt.gz” -exec rm -rf “{}” \; text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/disk_space?rev=1416064423&do=diff Get Disk Space One liner to get total, used and available disk space df -Pk|awk '{ sum2 += $2 ; sum3 += $3 ; sum4 += $4} END { print sum2/1024/1024 " G, " sum3/1024/1024 " G, " sum4/1024/1024 " G"}' text/html 2015-04-09T11:46:34+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/dns_validate?rev=1428579994&do=diff Validate DNS with nslookup To validate that the correct DNS entries are in the DNS Validate script (nsvalidate) #!/bin/bash HOSTN=$1 HOSTI=$2 RHOST=`nslookup -type=A $HOSTN|grep Address|grep -v "#53$"|cut -d" " -f2` if [ $HOSTI != $RHOST ]; then echo "Mismatch: $HOSTN expected $HOSTI but returned $RHOST" fi text/html 2021-05-03T11:27:58+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/doveadm_scripting?rev=1620041278&do=diff Doveadm scripting Below is an approach to scripting automatic processing of the Inbox. Delete old emails The script below is to purge emails from certain senders, and/or certain subject and after a certain number of days. The scripts are installed on text/html 2023-09-24T11:30:14+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/etc_skel?rev=1695555014&do=diff Update /etc/skel Set the default user parameters as follows dot toprc Below are the manual settings in the order of * Refresh every 1 second * Show individual CPUs * Color * Save settings permanently s 1 1 z SHIFT+W Setup top to custom specifications by create a .toprc file in /etc/skel text/html 2015-02-27T12:58:21+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/failed_login?rev=1425041901&do=diff Too many failed logins cat /dev/null > /var/log/faillog text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/find_command_to_ignore_svn_directories?rev=1416064423&do=diff Ignore svn directories but list all other directories that are not empty This one works to ignore svn directories but list all other directories that are not empty find <dome diretory path> -depth -type d -empty -name .svn -prune text/html 2014-12-04T12:45:37+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/find_command?rev=1417697137&do=diff find command Common uses Deleting old files with find command Below is an example of deleting MySQL backups older than 7 days BACKUPLOC="/path/to/backups" MYSQLBACKUPLOC="$BACKUPLOC/mysql" find $MYSQLBACKUPLOC/backup*.sql.gz -mtime +7 -exec rm {} \; text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/gnutls?rev=1416064423&do=diff HTTPS Virtual Hosts on Ubuntu 8.04 LTS Server Using gnutls for https virtual hosts Resources Extensible Development » HTTPS Virtual Hosts on Ubuntu 8.04 LTS Server OutOfOrder.cc mod_gnutls NameBasedSSLVHostsWithSNI - Httpd Wiki Steps done based on itwarlocks.com ftp://ftp.gnupg.org/gcrypt/libgpg-error/libgpg-error-1.9.tar.gz ftp://ftp.gnupg.org/gcrypt/libgcrypt/libgcrypt-1.4.6.tar.gz ftp://gnutls.hellug.gr/pub/gnutls/gnutls-2.10.0.tar.bz2 http://www.outoforder.cc/downloads/mod_gnutls/m… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/install_nagios_plugin_nrpe_redhat?rev=1416064423&do=diff Install Nagios Plugin and NRPE on Redhat Prerequisite install * xinetd * openssl-devel Redhat 3rd party libraries if added to yum can let you install nrpe via yum. However, below is an explanation of now to compile this locally. Download and Extract files text/html 2023-10-19T11:33:08+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/mail_server_setup?rev=1697715188&do=diff Mail Server Setup This is how I set up my mail server on * Ubuntu Ubuntu 14.04.5 LTS * Dovecot 2.2.9 (dovecot --version) * Postfix 2.11.0 (postconf mail_version) * Postfix Admin 2.3.5 * Squirrel Mail 1.4.22 * MySQL Ver 14.14 Distrib 5.5.57 (mysql text/html 2021-04-20T11:28:01+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/memory_check?rev=1618918081&do=diff Check High Memory usage and restart Apache Script to check memory usage and take the following actions if memory is high. Uses nagios plugin to get check memory usage. * Sends email to Admin * Restarts Apache * Saves process list in timestamped file in /tmp directory for reference text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/memory_usage?rev=1416064423&do=diff Find Memory Usage System memory used and free Total Used and Free Memory in MBytes (in that order) free -m|grep "buffers/cache"|cut -d":" -f2 Memory by Process Raw ps -e -orss=,args= | sort -b -k1,1n | pr -TW$COLUMNS Human readable ps -e -orss=,args= | sort -b -k1,1n | awk '{ split( "KB MB GB" , v ); s=1; while( $1>1024 ){ $1/=1024; s++ } print int($1) " " v[s] " " $2 }' text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/mime?rev=1416064423&do=diff MIME Information Resources Using PEAR's mimeDecode module evolt.org Using PEAR (Ubuntu) PHP MIME Decoder class MIME-tools - search.cpan.org PEAR path issue on Ubuntu Using PHP PEAR Manual generation and sending of a MIME mail Manual perform decoding Mail_mimeDecode - Example seeking optimal way to parse an email sent to my PHP script via PIPE php, email, parse Processing an email with attachment(s) using PHP and PEAR Mail class text/html 2020-06-22T11:27:28+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/most_common_packages_v2?rev=1592825248&do=diff Most Common Packages (v2) Below is the list of most common packages that are usually required by a Linux/Ubuntu server and is best to install it right away. Use aptitude command line option aptitude -y install <package_name> * mailutils * apache2-utils text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/most_common_packages?rev=1416064423&do=diff Most Common Packages Below is the list of most common packages that are usually required by a Linux/Ubuntu server and is best to install it right away. Use aptitude command line option aptitude -y install <package_name> * apache2-utils * backuppc text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/mount_samba_linux_share?rev=1416064423&do=diff Mounting Linux (Ubuntu) Shares in Windows (7) Allowing a directory in Linux to be accessible in Windows. Let's assume the Linux box is called ulin1 Initial steps * First choose the Linux Directory to mount. In this case it is /xyvol/ * Change the file permissions on this volume to be 770 and group to be root:<your user id> text/html 2015-01-02T12:56:58+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/mount_samba_windows_share?rev=1420203418&do=diff Mounting Windows Shares in Linux (Ubuntu) List what fstab has for reference later # cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid -o value -s UUID' to print the universally unique identifier # for a device; this may be used with UUID= as a more robust way to name # devices that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosui… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/nagios_nrpe_redhat?rev=1416064423&do=diff Steps to Install Nagios Remote Plug-ins Execution (NRPE) daemon The Monitored (target) host was running Redhat and the Monitoring (source) host was running Ubuntu. Install (Target) * yum -y install nagios-nrpe.x86_64 Configure (Target) * Edit /etc/nagios/nrpe.cfg text/html 2015-12-05T12:27:57+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/new_disk?rev=1449318477&do=diff Add New Disk in Linux Check Disk is installed fdisk -l|grep Disk Partition Disk Assuming new disk is sdc fdisk /dev/sdc Commands p - to print the partition table n - to create new w - to write Make file system Assume you created a single partition on sdc1 text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/new_network_card?rev=1416064423&do=diff Installing/Configuring New Network Adapter Linux (unlike Windows) has all of it's hardware adapters on the Kernel. When new hardware is installed it should show up in the lshw command. In this case if this is a new network card connected to PCI-E slot, it should show up under PCI-E. text/html 2016-06-22T11:28:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/new_server?rev=1466594927&do=diff Things to setup on a New (Ubuntu/Linux) server * Mail * Setup postfix * Setup alias such that local mail gets forwarded (/etc/aliases) * SSH * Generate SSH private and public keys * Tuning * Change swapiness and other parameters based on server needs - text/html 2015-12-05T12:27:57+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/nice?rev=1449318477&do=diff CPU Priority Nice is used to set CPU priority. Niceness runs from * -20, the highest priority, lowest niceness, to * 19, the lowest priority, highest niceness and * Zero is the default Yes, this is a bit counter-intuitive. To reduce to text/html 2022-03-28T11:28:49+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/php_ini?rev=1648466929&do=diff Recommended php.ini Settings The default php.ini settings are quite narrow. Considering today's server's memory, CPU, storage, etc, the first thing in a default install is to improve upon these. None of these should affect existing application, especially if you are increasing the resources (which is the case here) text/html 2020-11-30T12:27:56+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/php_server?rev=1606739276&do=diff PHP Server Variables <?php print_r($_SERVER); ?> text/html 2016-03-03T12:28:33+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/ping_test?rev=1457008113&do=diff Ping / TCP Ping Test Script to check for ping or TCP in a loop and email a limited number of times an error occurs #!/bin/bash # TIMEOUT=2 PORT=443 MAXEMAILS=40 IP=xxx.xxx.xxx.xxx EMAIL=someone@example.com SUBJECT=ping_test # errcnt=0 while true; do /usr/lib/nagios/plugins/check_tcp -H $IP -p $PORT -t $TIMEOUT if [ $? -ne 0 ] then (( errcnt += 1 )) if [ $errcnt -lt $MAXEMAILS ] then echo "Error Count: $errcnt"|mailx -s $SUBJECT $EMAIL … text/html 2017-01-04T12:25:42+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/pnp4nagios_averages?rev=1483532742&do=diff pnp4nagios extracting averages Extract average for previous month for given server, metric #!/bin/bash HN=$1 DB=$2 CF=$3 if [ "$DB" = "" ]; then DB="Memory_Usage" fi rrd1="${DB}.rrd" if [ "$CF" = "" ]; then CF="AVERAGE" fi PERFDATA_DIR=/var/lib/pnp4nagios/perfdata cd $PERFDATA_DIR # stime=$(date -d "`date +%Y%m01` -1 month" +%s) etime=$(date -d "`date +%Y%m01`" +%s) rrdtool fetch $PERFDATA_DIR/$HN/${DB}.rrd $CF -s $stime -e $etime | \ grep -v nan | \ awk '{sum+=$2; ++n} END {avg=s… text/html 2017-01-04T12:25:42+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/pnp4nagios_graphs?rev=1483532742&do=diff pnp4nagios extracting graphs Bash script to extract graphs for previous month #!/bin/bash # WDIR=/path/to/script OUTDIR=$WDIR/output/monthly_graphs mkdir -p $OUTDIR INPFILE=$WDIR/month_graphs.txt GRZIP=$WDIR/month_graphs.zip # # 1st day of last month stime=$(date -d "`date +%Y%m01` -1 month" +%s) # 1st day of this month etime=$(date -d "`date +%Y%m01`" +%s) # while read HN DB; do GURL="http://localhost/pnp4nagios/image?host=${HN}&srv=${DB}&view=1&start=${stime}&end=${etime}" PNGF="$OUTDIR… text/html 2018-12-06T12:27:55+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/pnp4nagios?rev=1544099275&do=diff Setting up pnp4nagios on Ubuntu 12.04 LTS Precise Pangolin Prerequisites nagios3 is installed. Install aptitude install pnp4nagios Configuring Bulk Mode with NPCD nagios.cfg In /etc/nagios3/nagios.cfg, update process_performance_data=1. Use the sed command or just edit the file! text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_autoresponder?rev=1416064423&do=diff Resources <http://nefaria.com/project_index/autoresponse/> <http://www.howtoforge.com/how-to-set-up-a-postfix-autoresponder-with-autoresponse> text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_client_tls?rev=1416064423&do=diff Postfix Client TLS Support Resource <http://www.postfix.org/TLS_README.html#client_tls> Instructions Generating SSL Key Run the following commands: cd /etc/postfix mkdir ssl cd ssl openssl genrsa -rand /etc/passwd:/etc/resolv.conf 2048 > smtpd.key chmod 400 smtpd.key openssl req -new -key smtpd.key > smtpd.csr # Enter the certificate information. # The "common name" is the mail server DNS name. text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_important_settings?rev=1416064423&do=diff Important Postfix Settings When using as SMTP relay for other servers on LAN Make sure to set inet_interfaces = all Sometimes this is set to localhost and will not allow relays Make sure to set mynetworks = 127.0.0.0/8 192.168.0/28 So the Local text/html 2015-01-09T12:47:51+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_relay_on_recipient_domain?rev=1420807671&do=diff Choose relay based on recipient domain To choose an SMTP relay server based on the recipient domain. /etc/postfix/main.cf #relayhost = #Remove any relayhost entry smtp_sender_dependent_authentication = yes transport_maps = hash:/etc/postfix/transport text/html 2014-12-04T12:45:37+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_report?rev=1417697137&do=diff Setting up daily mail reporting using pflogsumm pflogsumm is a perl script used for postfix mail reporting. Setup * Create directory /var/log/postfixrep * Copy pflogsumm into directory /usr/local/bin/pflogsumm * Create file /etc/cron.daily as below - change hard-coded email text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfix_spam_control?rev=1416064423&do=diff Resources to control spam using postfix * Text file of postfix configuration to reduce spam * <http://en.linuxreviews.org/HOWTO_Stop_spam_using_Postfix> * <http://www.howtoforge.com/block_spam_at_mta_level_postfix> * <http://www.akadia.com/services/postfix_uce.html> * Postfix configuration: reject_rbl_client * <http://www.yolinux.com/TUTORIALS/Postfix.html> * Postfix Configuration Parameters * HowTos-postfix restrictions - CentOS Wiki * Slamming Spam: A Guide for System Admini… text/html 2025-09-12T11:25:50+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/postfixadmin?rev=1757676350&do=diff Postfix Admin Install and Configure * Create web domain (or sub-domain) * Download stable release (not latest) * Extract files to domain root directory * Create database and user * Update Apache configuration to point to public directory text/html 2016-08-17T11:26:02+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/purge_linux_images?rev=1471433162&do=diff Purge Old Linux Headers/Images with aptitude If there is limited space on /boot, this becomes a necessity. Identify what packages are installed and what is current with the following commands: dpkg -l linux-image-\* | grep ^ii uname -a Sample output text/html 2015-03-10T11:51:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/redhat_epel?rev=1425988275&do=diff How to Enable EPEL Repository for RHEL Resources * How to Enable EPEL Repository for RHEL/CentOS 7.x/6.x/5.x * EPEL - FedoraProject * Index of /pub/epel/6Server/x86_64 * CentOS / RHEL: Delete Old Yum Repositories and Configuration Files Steps wget https://dl.fedoraproject.org/pub/epel/RPM-GPG-KEY-EPEL-6 wget http://mirror.us.leaseweb.net/epel/6/i386/epel-release-6-8.noarch.rpm cp RPM-GPG-KEY-EPEL-6 /etc/pki/rpm-gpg/ rpm -ivh epel-release-6-8.noarch.rpm yum repolist text/html 2025-02-10T12:29:17+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/resize_partition?rev=1739190557&do=diff Resize Partition (with preserving data) Steps to resizing partition without losing data PARTNUM=1 MPNAME=/dev/sda # MPNAME1=${MPNAME}${PARTNUM} # # Unmount partition umount $MPNAME1 # Check file system fsck -n $MPNAME1 # fdisk -l $MPNAME1 fdisk $MPNAME # Inside fdisk, do the below # p - print partition table # d - delete said partition # n - create new partition # w - to write changes back # # Check file system e2fsck -f $MPNAME1 # To resize to full partition size resize2fs $MPNAME1 # Get siz… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/reverse_tunnel?rev=1416064423&do=diff Creating a reverse tunnel – Use for creating your own VPN to a network behind firewall with no incoming ports open Setup for the SSH server that is connected to the internet (this is the server in the Home Network) * Establish a SSH server that is always ON. text/html 2015-08-03T11:46:31+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/rotate_logs?rev=1438602391&do=diff Log Rotation script Short of using logrotate, below is a quick and simple script to do the same. Script Example of haproxy log rotation #!/bin/bash # LOGDIR=/var/log LOGFILE=haproxy.log TARDIR=/data/log # LOGDIRFILE=${LOGDIR}/${LOGFILE} cp $LOGDIRFILE ${TARDIR}/${LOGFILE}.`date +%Y%m%d_%H%M%S` cat /dev/null > $LOGDIRFILE exit text/html 2025-12-06T12:26:24+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/screen?rev=1765023984&do=diff Screen Usage Practical screen usage notes Screen Commands List of more important screen commands to effectively operate screen When NOT in screen Command Description screen -D Power Detach - Close everything but keep the screens running in background. This is when you are done working! text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/scripted_email?rev=1416064423&do=diff Scripted Email Used to send email to list of people from flat file. Usually when sending from server you want the reply-to set correctly so the replies go to a proper email account. Input File The input file is cre.txt and has the following format text/html 2020-09-29T11:27:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/setup_network_groovy?rev=1601378863&do=diff Network Settings on Ubuntu Focus Location: /etc/netplan/00-installer-config.yaml # This is the network config written by 'subiquity' network: ethernets: enp0s3: addresses: - 192.168.1.60/24 gateway4: 192.168.1.1 nameservers: addresses: - 192.168.1.39 - 192.168.1.1 search: - example.org enp0s8: addresses: - 192.168.56.60/24 gateway4: 192.168.56.1 nameservers: {} version: 2 text/html 2023-02-12T12:30:07+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/setup_new_box?rev=1676205007&do=diff Setting up a new Linux box This page goes through the various settings that take place to setup a new Ubuntu box. In this case I was setting Ubuntu 12.04 Precise Pangolin. Install Configuration / Steps * Hardware details * AMD 3 core CPU * text/html 2026-01-22T12:26:21+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/setup_new_vm?rev=1769084781&do=diff Setting up a new Linux VM This is similar to Setup New Liux (Physical) Box This page goes through the various settings that take place to setup a new Ubuntu VM. In this case I was setting Ubuntu 20.10 Groovy Gorilla. Debian / Bookworm Specific steps for Debian/Bookworm Add non-free repositories text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/setup_postfix_relay?rev=1416064423&do=diff Setup Postfix to function as relay host Setup Postfix to function as relay host with authentication * Create a password maps file * You can create multiple entries in the sasl_passwd file for multiple domains echo "mailserver.example.com username:password" >> /etc/postfix/sasl_passwd chown root:root /etc/postfix/sasl_passwd chmod 600 /etc/postfix/sasl_passwd postmap /etc/postfix/sasl_passwd text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/sound_recording_in_linux?rev=1416064423&do=diff Sound Recording in Linux GUI - gnome sound recorder Application --> Sound & Video --> Sound Recorder Command line sound recorder To record in stereo (option -c 2), wav format (option -t), for 10 seconds (option -d) to file ed.wav arecord -d 10 -t wav -c 2 ed.wav text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/sq_config?rev=1416064423&do=diff Squirrel Mail Config - Postfix & Dovecot Below is the full configuration file (config.php) for Squirrel Mail with Postfix and Dovecot. Make sure * $data_dir = '/var/squirrelmail/data/'; * $attachment_dir = '/var/squirrelmail/attach/'; text/html 2019-07-07T11:25:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/squirrelmail?rev=1562498715&do=diff Squirrelmail Notes Squirrelmail back-end login The 1st invocation of Squirrelmail is slow for reasons I could not figure out. Also I have a number of filters setup on Squirrelmail that I want it to execute periodically - this allows my other IMAP clients to already have the mail in the correct folders. Setup this cronjob to take care of this. text/html 2015-03-10T11:51:15+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/ssh_filesystem?rev=1425988275&do=diff SSH Filesystem SSH Filesystem is a tool you would wonder why no one ever told you about. Instead of battling with Samba share or NFS, here is an easy solution that uses traditional SSH! You do need to install sshfs, but that is only a few seconds. text/html 2015-03-11T11:46:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/start_stop_script?rev=1426074407&do=diff Script to start/stop jobs Startup scripts samples. Start THIS DOES NOT QUITE WORK! The job starts but the pid is not the real pid! So the stop is also bad because of this. #!/bin/bash RUN_FILE=/var/run/somejob.pid nohup some-job > /dev/null 2>&1 & echo $! >> $RUN_FILE exit text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/starting_and_stopping_services_in_ubuntu_linux?rev=1416064423&do=diff Starting and Stopping Services in Ubuntu Linux sysv-rc-conf sysv-rc-conf is a great tool for the job Example: The following services were disabled using the tool â service 1 2 3 4 5 0 6 S â â ----------------------------------------------------------------------------â â db2exc [ ] [X] [X] [X] [X] [ ] [ ] [ ] â â clamav-da$ [ ] [X] [X] [X] [X] [ ] [ ] [ ] â â clamav-fr$ … text/html 2015-03-11T11:46:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/startup_run?rev=1426074407&do=diff Run command on startup This was tested on Redhat Append the below line to /etc/rc.local /sbin/runuser -s /bin/sh -l nobody -c '/etc/haproxy/start-hap' where * s - run in shell * l - run as user * c - command to run text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/startup_script_for_shellinabox?rev=1416064423&do=diff Start up script for Shell in a Box This is running on Ubuntu 12.04 #!/bin/sh # Start/stop the shellinaboxd daemon. # ### BEGIN INIT INFO # Provides: shellinaboxd # Required-Start: $syslog $time # Required-Stop: $syslog $time # Default-Start: 2 3 4 5 # Default-Stop: 0 1 6 # Short-Description: Shell in web browser # Description: Shell In A Box implements a web server that can export arbitrary # command line tools to a web based terminal emulato… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/stop_services?rev=1416064423&do=diff Stop Services on Ubuntu Below is the list of services that will pretty much bring the server to idle and do nothing. /etc/init.d/anacron stop /etc/init.d/cron stop /etc/init.d/apache2 stop /etc/init.d/mysql stop /etc/init.d/postfix stop /etc/init.d/courier-authdaemon stop /etc/init.d/courier-imap stop /etc/init.d/courier-imap-ssl stop /etc/init.d/dovecot stop /etc/init.d/privoxy stop /etc/init.d/rsync stop /etc/init.d/shellinaboxd stop text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/sudo_without_password?rev=1416064423&do=diff sudo without password Enable /etc/sudoers file for editing chmod 640 /etc/sudoers To enable edit /etc/sudoers as: 26c26 < %sudo ALL=(ALL:ALL) NOPASSWD: ALL --- > %sudo ALL=(ALL:ALL) ALL ---------- Keyword: visudo text/html 2016-06-22T11:28:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/sysctl_config?rev=1466594927&do=diff Settings for /etc/sysctl.conf For VM Host vm.swappiness = 0 vm.overcommit_memory = 2 vm.overcommit_ratio = 50 text/html 2015-04-22T11:42:47+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/throttle_process?rev=1429702967&do=diff Throttle background processes Example to throttle the number of unzips running when a large number of files need to be unzipped #!/bin/sh cd /data/somefolder/rzips TARD=/data/somefolder/anotherfolder LOGF=/data/somefolder/unziplog COUNTER=0 for z in *.zip; do LOGFILE=$LOGF/${z}.log CNTUNZIP=`ps -ef|grep -c unzip` while [ $CNTUNZIP -gt 51 ]; do sleep 1 CNTUNZIP=`ps -ef|grep -c unzip` done let COUNTER=COUNTER+1 echo "#: $COUNTER - Unzipping $z" nohup unzip $z -x LOG* -d $T… text/html 2025-01-01T12:30:53+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/ufw?rev=1735734653&do=diff UFW - Uncomplicated Firewall Setup of UFW on Precise Pangolin LTS 12.04 (Ubuntu) Steps The steps below will make the firewall active, but almost non-existent. This is a better way to start in my opinion especially for a soft firewall. My router takes care of the hard firewall and only ports that need to be open or open, so it begs to setup another filter here. So (at least for me) the sole purpose of this firewall is to block specific (also read dynamic) incoming (or may be even outgoing) t… text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/upgrade_to_lucid?rev=1416064423&do=diff Upgrading to Lucid <https://help.ubuntu.com/community/LucidUpgrades> text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/upgrading_wordpress_sites?rev=1416064423&do=diff Upgrading WordPress websites This is slightly different from the standard instructions although most of the standard instructions will apply. It is different because * The way I have installed WordPress is to enable it from a single install path for all websites text/html 2019-10-30T11:27:44+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/useful_network_tools?rev=1572434864&do=diff Commonly Used Network Commands / Tools Define DNS Servers Add/update DNS Server configurations in /etc/resolv.conf in the format nameserver <IP-Address>, one for each line. The /etc/resolve.conf file does get overwritten each time the system is rebooted. In Ububtu the /etc/resolvconf/resolv.conf.d/head is the source file and updating it keeps the changes permanent. In distros (such as Redhat) you can make the /etc/resolv.conf file read-only by text/html 2014-11-15T15:13:43+00:00 Anonymous (anonymous@undisclosed.example.com) https://tech.snathan.org/tech/linux/webalizer?rev=1416064423&do=diff webalizer info Dependent packages aptitude install libpng3-dev libgd2-xpm-dev