Add new user and add it to sudo group
2018-04-30
With 12.04 and later If the user already exists sudo usermod -aG sudo <username> To create the user adduser <username> –group sudoRead More →
Can’t send to hotmail.com , blocked by Outlook.com ?
2018-03-26
Do you see this error in your mail.log? “Please contact your Internet service provider since part of their network is on our block list (AS3140)” Go to this website to request Outlook team to remove your IP from their blocked list. https://support.microsoft.com/en-us/getsupport?oaspworkflow=start_1.0.0.0&wfname=capsub&productkey=edfsmsbl3&locale=en-us&ccsid=635611717755428181Read More →
Dovecot: (keywords_update_records): assertion failed: (data_offset >= sizeof(struct mail_index_record))
2018-03-24
This means your index is corrupted, we need to rebuild it find /user/emailfolder -name ‘dovecot*’ -type f -delete”Read More →
Secure Web/Mail/Database with certificate
2018-03-18
Web/Mail/Database can use the same certificate to allow its client to connect to the server. Postfix: postconf -e smtpd_tls_cert_file=’/etc/pki/tls/certs/cert.pem’ postconf -e smtpd_tls_key_file=’/etc/pki/tls/private/privkey.pem’ postconf -e smtpd_tls_CAfile=’/etc/pki/tls/certs/fullchain.pem’ Dovecot (POP3/IMAP server) SSL certificate settings are defined in Dovecot main config file, /etc/dovecot/dovecot.conf (Linux/OpenBSD) or /usr/local/etc/dovecot/dovecot.conf (FreeBSD): ssl = required ssl_cert = </etc/pki/tls/certs/cert.pem ssl_key = </etc/pki/tls/private/privkey.pem ssl_ca = </etc/pki/tls/certs/fullchain.pem Restarting Dovecot service is required. Apache (web server) On RHEL/CentOS, SSL certificate is defined in /etc/httpd/conf.d/ssl.conf. On Debian/Ubuntu, it’s defined in /etc/apache2/sites-available/default-ssl (or default-ssl.conf) On FreeBSD, it’s defined in /usr/local/etc/apache24/extra/httpd-ssl.conf. Note: if you’re running different version of Apache, the path will be slightly different (apache24 will be apache[_version_]). On OpenBSD, if you’re running OpenBSD 5.5 or earlier releases, it’s definedRead More →
Ubuntu: cp copy overwrite without prompting
2018-03-14
when you run: cp -rf /source/* /destination , it always ask you to confirm the overwrite action. Root cause: it’s probably the cp has been alias as cp -i Fix: /bin/cp -rf /source/* /destination or yes | cp -rf /source/* /destination Read More →
Restrict user to FTP only
2018-02-10
### Restrict User to FTP Only: A Guide for Enhanced Security and Access Control In any organization or server setup, securing user access is a critical component of maintaining data privacy, integrity, and overall system security. One common security measure is restricting users to only a specific service or protocol, such as **FTP** (File Transfer Protocol), to prevent unauthorized access to other parts of the system. If you are running an FTP server and need to ensure that a user has access to only FTP services, rather than providing full shell access to the system, this article will walk you through how to restrict aRead More →
Can’t Use apt i.e. /boot is 100% full
2018-01-19
NOTE: this is only if you can’t use apt to clean up due to a 100% full /boot 1. Get the list of kernel images Get the list of kernel images and determine what you can do without. This command will show installed kernels except the currently running one $ sudo dpkg –list ‘linux-image*’|awk ‘{ if ($1==”ii”) print $2}’|grep -v `uname -r` You will get the list of images somethign like below: linux-image-3.19.0-25-generic linux-image-3.19.0-56-generic linux-image-3.19.0-58-generic linux-image-3.19.0-59-generic linux-image-3.19.0-61-generic linux-image-3.19.0-65-generic linux-image-extra-3.19.0-25-generic linux-image-extra-3.19.0-56-generic linux-image-extra-3.19.0-58-generic linux-image-extra-3.19.0-59-generic linux-image-extra-3.19.0-61-generic 2. Prepare Delete Craft a command to delete all files in /boot for kernels that don’t matter to you using brace expansionRead More →
Dovecot – Iredmail SSL installation
2017-12-23
First of all, we need to order a certificate , this certificate is the same with normal web server certificate. The certificate will have 3 files: cert, key, cabundle. We use CentOS for example in below tutorial, please adjust the file to correct one on your server according to above description. Postfix (SMTP server) We can use postconf command to update SSL related settings directly: postconf -e smtpd_tls_cert_file=’/etc/pki/tls/certs/cert.pem’ postconf -e smtpd_tls_key_file=’/etc/pki/tls/private/privkey.pem’ postconf -e smtpd_tls_CAfile=’/etc/pki/tls/certs/fullchain.pem’ Restarting Postfix service is required. Dovecot (POP3/IMAP server) SSL certificate settings are defined in Dovecot main config file, /etc/dovecot/dovecot.conf (Linux/OpenBSD) or /usr/local/etc/dovecot/dovecot.conf (FreeBSD): ssl = required ssl_cert = </etc/pki/tls/certs/cert.pem ssl_key = </etc/pki/tls/private/privkey.pem ssl_ca = </etc/pki/tls/certs/fullchain.pem Restarting DovecotRead More →
Kill all close wait process
2017-11-09
We have seen many cases where the client didn’t close the connection correctly, the process is stuck at CLOSE_WAIT status, i never clear the database connection. We have this script to kill all close_wait connection. <? //Some apache process are in close_wait //replace apache2 with other stuff (httpd..) $cmd=”netstat -ntp | grep CLOSE_WAIT | grep apache2″; $process_array=array(“httpd”,”apache2″); $hostname=trim(shell_exec(“hostname -s”)); if($hostname==’ubuntu’) $cmd=”netstat -ntp “; debug(“Running $cmd”); $netstat=shell_exec($cmd); $file_log=”/tmp/kill_close_wait.txt”; $arr=explode(“\n”,$netstat); //print_r($arr); $test=false;//if we are debugging- if we are debug – it will not killl $log=false; foreach($arr as $line) { $line=preg_replace(‘/\s{2,}/’,’ ‘, $line); $arr2=explode(‘ ‘,$line); if(isset($arr2[6]) && $arr2[6]<>’-‘) { //print_r($arr3); $arr3=explode(‘/’,$arr2[6]); $process_id=$arr3[0]; if($process_id==0) continue; $process_name=$arr3[1]; if(!in_array($process_name,$process_array)) continue; debug(“Found:Read More →