Linux web hosting and server support tips

Category: Cpanel and WHM Page 1 of 3

How to remove or compress huge MySQL general and query log table

How to remove or compress huge MySQL general and query log table

If you have enabled MySQL general or slow logging, it can create quite big log, depending upon your MySQL usage/queries.
So we may have to periodically clear them to save space.

Please note that MySQL can save logs to either table or files. This document assumes you are using table as log output.

Files: slow_log.CSV and general_log.CSV (The location and the name of the file can be different)

By default, logging is to CSF file.

MYSQL supports run time clearing of these logs. So no need to restart the MySQL service.
Never delete the CSV file directly. It can crash MySQL.

Slow query log

SET GLOBAL slow_query_log='OFF';
DROP TABLE IF EXISTS slow_log2;
CREATE TABLE slow_log2 LIKE slow_log;
RENAME TABLE slow_log TO slow_log_backup, slow_log2 TO slow_log;
gzip /var/db/mysql/mysql/slow_log_backup.CSV 
DROP TABLE  slow_log_backup;
SET GLOBAL slow_query_log = 'ON';

General log

USE mysql;
SET GLOBAL general_log = 'OFF';
DROP TABLE IF EXISTS general_log2;
CREATE TABLE general_log2 LIKE general_log;
RENAME TABLE general_log TO general_log_backup, general_log2 TO general_log;
gzip /var/db/mysql/mysql/general_log_backup.CSV 
DROP TABLE  general_log_backup;

What we did is create new log table, move current log file to a backup copy and compress the backup and remove it.

How To Install PHP 7 On A cPanel/WHM Server With EasyApache 3

How To Install PHP 7 On A cPanel/WHM Server With EasyApache 3

Latest versions of cPanel come with EasyApache 4 which provides lots of new features like native support for multiple PHP versions, PHP 7 support, very fast, etc. So it is recommended to migrate to EasyApache 4. However, if you cannot migrate EasyApache 4 because of some reason (Example: Tomcat support), you will have to compile the PHP 7 manually from source.

To migrate to EasyApache for, just run the below command. cPanel will try to build a matching PHP setup using EasyApache 4.

/scripts/migrate_ea3_to_ea4 --run

If anything goes wrong during the upgrade process you can always go back with /scripts/migrate_ea3_to_ea4 –revert –run

Manually install PHP 7

Following steps are tested with cPanel 11.64.0.36 and CentOS 6.9 64 bit. The PHP handler should be suphp to get this working.

cd /usr/local/src/
wget http://php.net/distributions/php-7.0.22.tar.gz #Go to php.net site to find the latest version
tar xvf php-7.0.22.tar.gz

Build it.

 #./configure  --enable-bcmath --enable-calendar --enable-exif --enable-ftp --enable-gd-native-ttf --enable-libxml --enable-mbstring --enable-pdo=shared --enable-sockets --enable-zip --prefix=/usr/local/php70  --with-curl=/opt/curlssl/ --with-freetype-dir=/usr --with-gd --with-gettext --with-imap=/opt/php_with_imap_client/ --with-imap-ssl=/usr --with-jpeg-dir=/usr --with-kerberos --with-libdir=lib64 --with-libxml-dir=/opt/xml2/ --with-mcrypt=/opt/libmcrypt/ --with-mysqli --with-openssl=/usr --with-openssl-dir=/usr --with-pcre-regex=/opt/pcre --with-pdo-mysql=shared --with-pdo-sqlite=shared --with-pic --with-png-dir=/usr --with-xpm-dir=/usr --with-zlib --with-zlib-dir=/usr

You may add any additional parameters required. You can run ./configure --help to see all available options first.
Important: Do not forget to set the "--prefix=/usr/local/php70". Otherwise, your existing PHP installation will be lost.

 make
 make install

If everything is successful, the PHP binaries will be installed in "/usr/local/php70/bin/" directory.

Copy the default php.ini:

 cp -pr /usr/local/src/php-7.0.22/php.ini-production /usr/local/php70/lib/php.ini

Add pdo,opcache, other modules to php.ini file.

 echo "extension=pdo.so" >> /usr/local/php70/lib/php.ini
 echo "extension=pdo_mysql.so" >> /usr/local/php70/lib/php.ini
 echo "zend_extension=opcache.so" >> /usr/local/php70/lib/php.ini

Verify the installation

/usr/local/php70/bin/php -v
PHP 7.0.22 (cli) (built: Aug 5 2017 01:56:23) ( NTS )
Copyright (c) 1997-2017 The PHP Group
Zend Engine v3.0.0, Copyright (c) 1998-2017 Zend Technologies
with Zend OPcache v7.0.22, Copyright (c) 1999-2017, by Zend Technologies

Now link our new PHP 7 installation with Apache web server

Generate the PHP config:

cat >  /usr/local/apache/conf/php70.conf << EOF
AddType application/x-httpd-php7 .php7 .php

    suPHP_AddHandler application/x-httpd-php7

EOF

Add new handler to suphp

Edit the /opt/suphp/etc/suphp.conf and add below code, at the end of the handlers list to enable PHP7 handler.

;Handler for php-scripts
#... existing handlers are here ... put yours below them
application/x-httpd-php7="php:/usr/local/php70/bin/php-cgi"

Now add our custom php config file to EasyApache list so that the changes will not be lost future EasyApache builds.

There are two options here. You can either go into WHM and edit the post_virtualhost_global.conf file from there or you just run: vi /usr/local/apache/conf/includes/post_virtualhost_global.conf. Add the line below in that file and you should be all done.

Include /usr/local/apache/conf/php70.conf

Now restart Apache

service httpd restart

Configure a website To Use This new PHP 7
Add following code to .htaccess file(/home/username/public_html/.htaccess)

AddType application/x-httpd-php7 .php7 .php

Disable/suspend email service for one domain – cPanel

Disable/suspend email service for one domain

From version 56, cPanel provides API support to disable email service for domain or email accounts. Please note this limit cannot be override by the user from their cPanel. This can be very helpful if there is any spamming activity and you just want to disable the email service feature for the domain for the time being.

You can run the below commands through SSH console

To suspend email service for a the cPanel user “aacenyor”

whmapi1 suspend_outgoing_email user=aacenyor

For unsuspending the account, please run the below command:

whmapi1 unsuspend_outgoing_email user=aacenyor

If you are not comfortable with SSH, you can also call these through browser XML.

Example:

To suspend
https://hostname.example.com:2087/cpsess##########/xml-api/suspend_outgoing_email?api.version=1&user=aacenyor

where replace hostname.example.com with your hostname
replace cpsess########## with WHM session id.

To un suspend
https://hostname.example.com:2087/cpsess##########/xml-api/unsuspend_outgoing_email?api.version=1&user=aacenyor

For older versions cPanel, you may refer to this below forum from cPanel. There is a workaround

https://forums.cpanel.net/threads/how-do-i-block-one-domain-from-sending-email-from-my-server.223731/#post920912

FTP connectivity problem:: No route to host

FTP connectivity problem

If you are getting following error while FTP directory listing, follow the solution provided below

———-
ftp> ls
227 Entering Passive Mode (108,61,169,245,167,161).
ftp: connect: No route to host
———-

Solution

Edit /etc/sysconfig/iptables-config and add this line:

IPTABLES_MODULES=”ip_conntrack_ftp”

Save it and restart iptables.
That’s because passive mode use non standard ports to communicate, so you need to keep trak of the ftp connections and iptables will allow them when necessary.

However, you will need to do this every time you reboot your RedHat server. Thus as a more permanent solution you can persistently load this module after each reboot by creating executable shell script within /etc/sysconfig/modules/ directory. Create file /etc/sysconfig/modules/iptables.modules with the following content:

#!/bin/sh
exec /sbin/modprobe ip_conntrack_ftp >/dev/null 2>&1

Once you save this file you also need to make it executable:
# chmod +x /etc/sysconfig/modules/iptables.modules

Another solution is specify the passive ports that will be used on FTP server configuration, then open those specific ports on firewall.

CSR generation for UCC certificates

Unified Communications (UC) Certificates (also called SAN Certificates) use Subject Alternative Names o secure multiple sites (e.g. fully qualified domain names) with one certificate. Four SANs are included in the base price of the UC Certificate, but you can purchase additional names at any time during the lifetime of the certificate.

With a UC Certificate, you can secure:

www.linuxwebservertips.in
www.example2.com
www.example3.net
mail.example.net
dev.example2.com

The CSR generation process is little different for creating an UCC certificates. We will have to create a Openssl based configuration file and then create private key and CSR from it.

Step 1: Create a custom OpenSSL Conf file.

The following is an example conf file that can be used for creation of a SAN/UCC cert. Save it as multissl.conf

———–
[ req ]
default_bits = 2048
default_keyfile = privkey.pem
distinguished_name = req_distinguished_name
req_extensions = req_ext # The extentions to add to the self signed cert

[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = US
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = Iowa
localityName = Locality Name (eg, city)
localityName_default = Iowa City
organizationName = Organization Name (eg, company)
organizationName_default = The University of Iowa
organizationalUnitName = Organizational Unit Name (eg, section)
organizationalUnitName_default = Domain Control Validated
commonName = Common Name (eg, YOUR SSL domain name)
commonName_max = 64

[ req_ext ]
subjectAltName = @alt_names

[alt_names]
DNS.1 = www.linuxwebservertips.in
DNS.2 = www.example1.com
DNS.3 = example2.com
———–

Notes:

The alt_names section (DNS.1, DNS.2, ….) are the list of all other domain names you wish to secure with this cert. Additional can be added such as DNS.4, etc.
The following examples assume that you name the above config file file multissl.conf (if it is named differently you must adjust the filename in the below examples accordingly.
Step 2: Generate the Private key and CSR with OpenSSL

Execute the following OpenSSL command

$ openssl req -nodes -newkey rsa:2048 -keyout serverfqdn.key -out multidomain.csr -config multissl.conf

* Replace “serverfqdn” with the fully qualified domain name of the server (ie: sample.server.uiowa.edu). Note: it may also be helpful to add a year to the filename.

You will then see output and be prompted for configuration as seen in the following example. Enter your details accordingly.

——————————————
$ openssl req -nodes -newkey rsa:2048 -keyout serverfqdn.key -out multidomain.csr -config multissl.conf
Generating a 2048 bit RSA private key
………………………………….+++
…………………………………………………………+++
writing new private key to ‘serverfqdn.key’
—–
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter ‘.’, the field will be left blank.
—–
Country Name (2 letter code) [US]:US
State or Province Name (full name) [Iowa]:Iowa
Locality Name (eg, city) [Iowa City]:Iowa City
Organization Name (eg, company) [The University of Iowa]:My Company name
Organizational Unit Name (eg, section) [Domain Control Validated]:IT SUPPORT
Common Name (eg, YOUR SSL domain name) []:www.linuxwebservertips.in
——————————————

Note: Replace www.linuxwebservertips.in with the “primary” domain name you want secured with this certificate (likely, but not necessarily the hostname of the machine).

At this point you should have the new key file, and CSR. Save the key file in a secure place, it will be needed to apply the new certificate. The CSR can now be submitted to request the SSL Cert.

Strong TLS/SSL Security on your server

SSL Report : www.linuxwebservertips.in

ssllab

 

 

 

 

This is a simple guide for setting up a strong TLS/SSL configuration on your server.

If you configure a web server’s TLS configuration, you have primarily to take care of three things:

1. disable SSL 2.0 (FUBAR) and SSL 3.01 (POODLE),
2. disable TLS 1.0 compression (CRIME),
3. disable weak ciphers (DES, RC4), prefer modern ciphers (AES), modes (GCM), and protocols (TLS 1.2).

 

Your Server’s Certificate

Let’s start with your digital certificate, which is at the core of HTTPS. The certificate enables clients to verify the identity of servers, through a chain of trust from your server’s certificate through intermediate certificates and up to a root certificate trusted by users’ browsers. Your server certificate should be 2048 bits in length. Using 4096 bit certificate is more secure however it require more computation times and hence slow compared to 2048 bit certs.

 

Basic HTTPS Setup

Here are basic SSL configurations, first for Apache:

;
...
SSLEngine on
SSLCertificateFile /etc/ssl/certs/your_cert
SSLCertificateChainFile /etc/ssl/certs/chained_certs
SSLCertificateKeyFile /etc/ssl/certs/your_private_key
<;/VirtualHost>;

And then for Nginx:

server {
...
ssl on;
ssl_certificate /etc/ssl/certs/your_cert_with_chain;
ssl_certificate_key /etc/ssl/certs/your_private_key;
ssl_session_cache shared:SSL:50m;
ssl_session_timeout 10m;
}

In Nginx, the ssl_certificate parameter is confusing. It expects your certificate plus any necessary intermediate certificates, concatenated together.

Make sure all of these files are at least mode 0444, except your private key, which should be 0400.

 

Software versions

On the server side you should update your OpenSSL to 1.0.1c+ so you can support TLS 1.2, GCM, and ECDHE as soon as possible. Fortunately that’s already the case in Ubuntu 12.04 and later.

On the client side the browser vendors are starting to catch up. As of now, Chrome 30, Internet Explorer 11 on Windows 8, Safari 7 on OS X 10.9, and Firefox 26 all support TLS 1.2.

 

Cipher Suite Configuration

The recommended cipher suites for Apache are follows

SSLCipherSuite EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH
SSLHonorCipherOrder on

The recommended cipher suite for backwards compatibility (IE6/WinXP):

SSLCipherSuite EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4
SSLHonorCipherOrder on

 

And here’s the same configuration for Nginx:

ssl_ciphers 'EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH';
ssl_prefer_server_ciphers on;

The recommended cipher suite for backwards compatibility (IE6/WinXP):

ssl_ciphers "EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH:ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:HIGH:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
ssl_prefer_server_ciphers on;

If your version of OpenSSL is old, unavailable ciphers will be discarded automatically. Always use the full ciphersuite above and let OpenSSL pick the ones it supports.

The ordering of a ciphersuite is very important because it decides which algorithms are going to be selected in priority. The recommendation above prioritizes algorithms that provide perfect forward secrecy.

 

Prioritization logic

ECDHE+AESGCM ciphers are selected first. These are TLS 1.2 ciphers and not widely supported at the moment. No known attack currently target these ciphers.
PFS ciphersuites are preferred, with ECDHE first, then DHE.
AES 128 is preferred to AES 256.  At the moment, AES128 is preferred, because it provides good security, is really fast, and seems to be more resistant to timing attacks.
In the backward compatible ciphersuite, AES is preferred to 3DES. BEAST attacks on AES are mitigated in TLS 1.1 and above, and difficult to achieve in TLS 1.0. In the non-backward compatible ciphersuite, 3DES is not present.
RC4 is removed entirely. 3DES is used for backward compatibility

 

Protocol Support: SSL or no SSL

To prevent downgrade attacks and poodle attack, we will also disable old SSL protocols

For Apache:

SSLProtocol all -SSLv2 -SSLv3

For Nginx:

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

This disables all versions of SSL, enabling only TLS 1.0 and up. All versions of Chrome and Firefox support at least TLS 1.0.

How to Disable SSLv3 for Apache,Nginx, Litespeed, cPanel

The POODLE bug is a new bug discovered by Google in the SSLv3 protocol. The fix is easy, disable support for SSLv3.

See the google security blog for more info on the bug: http://googleonlinesecurity.blogspot.nl/2014/10/this-poodle-bites-exploiting-ssl-30.html.

 

Fix POODLE

To fix the bug, disable SSLv3 and use a secure cipherlist. SSL v2 is also insecure, so we need to disable it too.

So edit the Apache config file and add following

SSLProtocol All -SSLv2 -SSLv3

All is a shortcut for +SSLv2 +SSLv3 +TLSv1 or – when using OpenSSL 1.0.1 and later – +SSLv2 +SSLv3 +TLSv1 +TLSv1.1 +TLSv1.2, respectively. The above line enables everything except SSLv2 and SSLv3

And then restart the Apache service

service httpd restart

 

cPanel/WHM

If you have a cPanel server, you should not edit Apache configurations directly, instead you can do this from WHM.

 

Apache-Configuration-WHM

 

1. Visit your server’s WHM Panel ( https://<yourserversip>:2087 )
2. Navigate to the Apache Configuration Panel of WHM.
3. Scroll down to the ‘Include Editor’ Section of the Apache Configuration.
4. Click ‘Pre Main Include’, which will jump to the corresponding section. Via the drop-down selector, choose ‘All Versions’.
5. An empty dialogue box will appear allowing you to input the needed configuration updates. In this box, copy and paste the following:

SSLProtocol All -SSLv2 -SSLv3
SSLHonorCipherOrder On

 

For Nginx

If you’re running an NGINX web server that currently uses SSLv3, you need to edit the NGINX configuration (nginx.conf). You will need to add the following line to your server directive:

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;

Then restart the nginx service

service nginx restart

For LiteSpeed:

Update to LiteSpeed version 4.2.18.

For more information about Litespeed & POODLE: http://www.litespeedtech.com/support/forum/threads/lsws-4-2-18-released-%E2%80%94-addresses-poodle-sslv3-vulnerability.9948/

Note about Mail Servers:

The POODLE attack requires the client to retry connecting several times in order to downgrade to SSLv3, and typically only browsers will do this. Mail Clients are not as susceptible to POODLE. However, users who want better security should switch to Dovecot until we upgrade Courier to a newer version.

For cpsrvd:

1. Go to WHM => Service Configuration => cPanel Web Services Configuration
2. Make sure that the “TLS/SSL Protocols” field contains “SSLv23:!SSLv2:!SSLv3”.
3. Select the “Save” button at the bottom.

For cpdavd:

1. Go to WHM => Service Configuration => cPanel Web Disk Configuration
2. Make sure that the “TLS/SSL Protocols” field contains “SSLv23:!SSLv2:!SSLv3”.
3. Select the “Save” button at the bottom.

For Dovecot:

1. Go to WHM => Service Configuration => Mailserver Configuration.
2. SSL Protocols should contain “!SSLv2 !SSLv3”. If it does not, replace the text in this field.
3. Go to the bottom of the page, and select the Save button to restart the service.

For Courier:

Courier has released a new version to mitigate this as of 10/22, until we have an opportunity to review, test, and publish the new version of Courier please switch to Dovecot for enhanced security.

For Exim:

1. Go to Home » Service Configuration » Exim Configuration Manager
2. Under Advanced Editor, look for ‘openssl_options’.
3. Make sure the field contains “+no_sslv2 +no_sslv3”.
4.Go to the bottom of the page, and select the Save button to restart the service.

 

For Lighttpd:

Lighttpd releases before 1.4.28 allow you to disable SSLv2 only.

If you are running at least 1.4.29, put the following lines in your configuration file:

ssl.use-sslv2 = "disable"
ssl.use-sslv3 = "disable"

How to verify the Poodle is disabled

You can use a website like http://poodlebleed.com/ for a web based check.

 

Manual check

To make sure services on your server are not accepting SSLv3 connections, you can run the openssl client on your server against the SSL ports. This command is run as follows:

openssl s_client -connect linuxwebservertips.in:443 -ssl3

If it fails (which is what you want), you should see something like this at the top of the output:

3078821612:error:14094410:SSL routines:SSL3_READ_BYTES:sslv3 alert handshake failure:s3_pkt.c:1257:SSL alert number 40
3078821612:error:1409E0E5:SSL routines:SSL3_WRITE_BYTES:ssl handshake failure:s3_pkt.c:596:

Shellshock How to check if you are vulnerable

A new vulnerability has been found that potentially affects most versions of the Linux and Unix operating systems, in addition to Mac OS X. Known as the “Bash Bug” or “ShellShock,” the GNU Bash Remote Code Execution Vulnerability could allow an attacker to gain control over a targeted computer if exploited successfully. And because Bash is everywhere on Linux and UNix-like machines and interacts with all parts of the operating system, everyone anticipates that it will have lot of repercussions.

How does Shellshock work?

Shellshock exploits a flaw in how Bash parses environment variables; Bash allows functions to be stored in environment variables, but the issue is Bash will execute any code placed after the function in the environment variable value.

For example, an environment variable setting of VAR=() { ignored; }; /bin/id will execute /bin/id when the environment is imported into the bash process.

I am vulnerable?

You can check if you’re vulnerable by running the following lines in your default shell.

env X=”() { :;} ; echo vulnerable” `which bash` -c “echo Check completed”

If you see the word “vulnerable” echo’d back , then you’re at risk.

How Shellshock is Impacting the Web

The most likely route of attack is through Web servers utilizing CGI (Common Gateway Interface), the widely-used system for generating dynamic Web content. An attacker can potentially use CGI to send a malformed environment variable to a vulnerable Web server. The attacker is able to inject environment variables inside all bash process spawned by a web server under the CGI specification. This will occur directly if the CGI script is programmed in bash or indirectly by system calls inside other types of CGI scripts since the environment will propagate to the sub-shell. The vulnerability will automatically be triggered at the shell process instantiation. Furthermore if specific headers are used as attack points, the payload may not appear in the webserver logs, letting a compromise occur with virtually no trace of the intrusion.

Example:

CGI stores the HTTP headers in environment variables. Let’s say the example.com is running a CGI application written in Bash script.

We can modify the HTTP headers such that it will exploit the shellshock vulnerability in the target server and executes our code.

curl -k http://example.com/cgi-bin/test -H “User-Agent: () { :;}; echo Hacked > /tmp/Hacked.txt”

Here, the curl is sending request to the target website with the User-Agent containing the exploit code. This code will create a file “Hacked.txt” in the “/tmp” directory of the server.

What can I do to protect myself?

Major operating software vendors including RedHaT, CentOS, etc are already released a initial patch for this bug.

Debian—https://www.debian.org/security/2014/dsa-3032

Ubuntu—http://www.ubuntu.com/usn/usn-2362-1/

Red Hat—https://access.redhat.com/articles/1200223*

CentOS—http://centosnow.blogspot.com/2014/09/critical-bash-updates-for-centos-5.html

Novell/SUSE— http://support.novell.com/security/cve/CVE-2014-6271.html

If a patch is unavailable for a specific distribution of Linux or Unix, it is recommended that users switch to an alternative shell until one becomes available.

Need expert assistanace?

I can help you to patch your server against this bug and make sure you and your customers are secure. Mail me at therealfreelancer[at]gmail[dot]com.

Limit /throttle rsync transfer speed

If you use the rsync utility to keep your backups synchronized between your servers or with a local machine, you might want to prevent the script from using too much bandwidth. However, rsync makes a lots of network I/O. The point of limiting bandwidth is to make sure your backup scripts don’t clog up the network connection.

Naturally, limiting the amount of bandwidth your backups are using is going to make them happen more slowly, but if you can deal with that, this is the way to do it.

 

Normal rsync command

rsync –avz -e ‘ssh’ /path/to/source user@remotehost:/path/to/dest/

What you’ll want to do is use the –bwlimit parameter with a KB/second value, like this:

rsync –bwlimit=<kb/second> –avz -e ‘ssh’ /path/to/source user@remotehost:/path/to/dest/

So if you wanted to limit transfer to around 10000KB/s (9.7MB/s), enter:

rsync –bwlimit=10000 –avz -e ‘ssh’ /path/to/source user@remotehost:/path/to/dest/

 

Example:-

rsync –bwlimit=10000 –avz -e ‘ssh’ /backup/ root@192.168.0.51:/backup/

Blocking spoofed outgoing mails from your cPanel server

Spoofing is where the mail headers are manipulated to appear as if the mail comes from some other domain. When emails are set to be from an email address on your domain and bounce, they are sent to our servers, attempting to deliver themselves to that mailbox. Generally, you will never see these emails; however, if the email spoofer happens to configure the “From:” header to be a real email box, the bounce will come back to your mailbox and you will receive the email. There is a high chance that a very large number of spam message already sent from server. This can cause high load in the server and sometimes leads to the blacklist of your mail server IP address.

There are two ways in which a spoofed mail can be created.

1. Exploiting vulnerable form to mail scripts to send out spoofed mails through local mail agent.
2. Using stolen mail account login details to send spoofed mails through SMTP authentication.
Let’s look at a solution on how spoofing can be prevented in Exim mail servers commonly implemented in cPanel/WHM servers.

I. Blocking all un-authenticated spoofed outbound emails
1. Login to WHM >> EXIM CONFIGURATION MANAGER >> ADVANCED EDITOR

2. Add the following entry in the top using Add additional configuration setting:

domainlist remote_domains = lsearch;/etc/remotedomains

3. Add the following code under acl_not_smtp :

deny
condition = ${if ! match_domain{${domain:${address:$h_From:}}}{
+local_domains : +remote_domains}}
message = Sorry, you don’t have\
permission to send email from this server with a header that\
states the email is from ${lc:${domain:${address:$h_from:}}}.
accept

Here, the ACL will check for the presence of domain name part of the from address in either of the files – /etc/localdomains or /etc/remotedomains. If there is a mismatch, server will reject the email.

 

II. Blocking all authenticated spoofed outbound emails
1. WHM >> EXIM CONFIGURATION MANAGER >> ADVANCED EXIM EDITOR

2. Search for acl_smtp_data and add the following lines under it:

deny
authenticated = *
condition = ${if or {{ !eqi{$authenticated_id} {$sender_address} }\
{ !eqi{$authenticated_id} {${address:$header_From:}} }\
}\
}
message = Your FROM address ( $sender_address , $header_From )
must match your authenticated email user ( $authenticated_id ).
Treating this as a spoofed email.
Here, for all authenticated users, the rule will check whether the authenticated userid matches with the from address. If it matches, it will allow the email. Else, it will display the message “Your FROM must match your authenticated email user. Treating this as spoofed email”

 

PS: If the acl_smtp_data is mentioned as something else(like acl_smtp_data = check_message), locate check_message and add the above lines just under it.
IMPORTANT points to keep in mind
a. POP before SMTP won’t work with this setting. You will have to ask your customers to use the option – “My Server Requires Authentication” in the SMTP settings of their email client.
b. Username in the format user+domain.com will not work. They have to use user@domain.com instead.

Also your customer cannot change the from field to something other than original authentcated user. People use this method in Website Contact forms.

 

Setting SPF records

Another way to prevent spoofing is using SPF records. You must specify valid spf records for your domain, so that only the intended people or server can send mails on behalf of your domain name.

Page 1 of 3

Powered by WordPress & Theme by Anders Norén