Life with IP Network

Saturday, May 30, 2015

Live file synchronization across multiple Linux servers using LSYNC

At first please take note I have implemented this in Debian Server.
Perform SSH Login Without Password from Master Server to Slave Server
Master Server:
#ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/home/root/.ssh/id_rsa):[Just press Enter key]
Enter passphrase (empty for no passphrase): [Just Press enter key]
Enter same passphrase again: [Just Pess enter key]
Your identification has been saved in /home/root/.ssh/id_rsa.

#ssh-copy-id -i ~/.ssh/id_rsa.pub remote-ip

Now test from master server,
# ssh remote-ip
[It will not ask for password and take you to the remote server]

Now Install Lsync on Master Server:
#apt-get update
#apt-get install -y lua5.1 liblua5.1-dev pkg-config rsync asciidoc

# vim /etc/lsyncd/lsyncd.conf.lua
settings {
logfile = "/var/log/lsyncd/lsyncd.log",
statusFile = "/var/log/lsyncd/lsyncd-status.log",
statusInterval = 10
}
sync {
default.rsync,
source="/home/",
target="remote-ip:/home/",
rsync = {
compress = true,
verbose = true,
owner = true,
group = true,
perms = true,
acls = true,
rsh = "/usr/bin/ssh -p 22 -o StrictHostKeyChecking=no"}
}

sync {
default.rsync,
source="/var/mail/",
target="remote-ip:/var/mail/",
rsync = {
compress = true,
verbose = true,
owner = true,
group = true,
perms = true,
acls = true,
rsh = "/usr/bin/ssh -p 22 -o StrictHostKeyChecking=no"}
}
[Save and Exit]

#mkdir /var/log/lsyncd/

#touch /var/log/lsyncd/lsyncd.log

#touch /var/log/lsyncd/lsyncd-status.log

#service lsyncd start

Slave Server:
#apt-get install rsync

Now test from Master Server:
#cd /home/

#touch test-file

Slave Server:
#cd /home/

#ls -lah

############# End of Lsync Configuration #############

*** Keep in mind if you want to backup a mail server to a secondary one you have to move a copy of /etc/passwd, /etc/shadow, /etc/group file from master server to backup server. Follow below steps to do that once in a day ***

Slave server:
#mkdir /root/user-backup-from-master-server

Master server:
#vim /usr/local/src/backup-users
scp /etc/passwd /etc/group /etc/shadow root@remote-ip:/root/user-backup-from-master-server
[Save and Exit]

#chmod 755 /usr/local/src/backup-users

#vim /etc/crontab
01 15 * * * root /usr/local/src/backup-users
[Save and Exit]

#/etc/init.d/cron restart

** This procedure will transfer a copy of /etc/passwd, /etc/group, /etc/shadow files everyday at 3:01PM from Master server to Slave server.

Tuesday, March 24, 2015

Multiple page redirection from single Linux Server using Apache2

I have a Linux server with Apache2 as its web service. I want to redirect two sites pointed to that server to other two websites. At first I was confused how to do that as I work in networking section. Later I got help anyway and I am going to share the solution with you.

First I have to change default page 'index.html' to 'index.php'.

Then I have given below code to redirect those to two sites to another two websites.

##################################
<?php
$actual_link = "$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
if($actual_link == "www.xyz.com/")
    $redirect_page = "http://www.anotherone.com/";
if($actual_link == "web2.xyz.com/")
    $redirect_page = http://www.anothertwo.com/;
?>
<html>
    <head>
        <meta http-equiv="refresh" content="3;url=<?php echo $redirect_page ?>" />
    </head>
    <body>
        <h1>Please wait, You are redirecting... </h1>
    </body>
</html>
#################################

I am happy with this simple solution. You??

Monday, January 19, 2015

SMTP Authentication using Dovecot

Sometimes we got complain from our clients that they cannot send mails using OutLook form different ISP/Network. To avoid this kind of inconvenience we can configure TLS authentication from server.

Step: 1

vim /etc/dovecot/conf.d/10-master.conf [Edit / Add the following Lines]

# Postfix smtp-auth

unix_listener /var/spool/postfix/private/auth {

mode = 0666

user = postfix

group = postfix

}

Step: 2

Now come to postfix directory and edit main.cf file like following

# TLS parameters
smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
########## Enable TLS ########
smtpd_tls_security_level = may
smtpd_tls_received_header = yes
smtpd_tls_auth_only = no
smtp_tls_note_starttls_offer = yes
######################################
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

#Authentication from dovecot

smtpd_sasl_type = dovecot

smtpd_sasl_path = private/auth

smtpd_sasl_auth_enable = yes

smtpd_sasl_security_options = noanonymous

smtpd_helo_required = yes

smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject
broken_sasl_auth_clients = yes
smtpd_sender_restrictions = permit_sasl_authenticated

Step 3:
Now we need to enable the required SMTP port. Generally we see many providers do not allow default SMTP port 25 and SMTPS port 465. I usually suggest SMTP Submission port 587 in this cases. But keep in mind do not disable default SMTP port 25 from your server. It is required to SMTP communication between server to server.

SMTP Port 25 disable and Enable

To enable port 587, edit the file /etc/postfix/master.cf

vim /etc/postfix/master.cf

and remove the # in front of the line:

#submission inet n – n – – smtpd

so that it looks like this:

submission inet n – n – – smtpd

and restart postfix:

/etc/init.d/postfix restart

Step: 4

Now check all the necessary ports are listening in your server.

#netstat –nat | grep LISTEN

And check for the ports 25 (SMTP), 587 (SMTP Submission), 143 (IMAP), 110 (POP3)

Step: 5

Modify the outlook email client configuration of users like below image.

You are done.