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Change MAC Address Loopback Adapter

My Blog is receiving a lot of search query for the change loopback adapter mac address. Previously, I have written article on spoofing mac address using Loopback Adapter . You may refer to the same blog post if you need to install Loopback Adaptor.In this blog I am writing how to change MAC address of Loopback adapter in this blog.STEPS:1. Goto Device Manager  from Control panel or Using devmgmt.msc from RUN

2. Expand Network Adapter and right click properties.

Device Manager Loopback Adaptor Properties
3. Click Advanced Tab and Click Network Address add MAC address in the format as in the Screen Shot below.

Loopback adaptor MAC address

4. You can conform the change of mac Address using ipconfig /all from Command and check Hardware Address.

Asp.Net Development Server Remote Access

ASP.NET Development  server is used by visual studio as a Default Webserver this server is only available in localhost interface. development server remote access can be enabled as discussed below.After this is enabled this can be accessed from LAN and WAN

1. Install Web Farm Network, Application Request Routing and URL Rewriter tools either by using Web Platform installer or direct downloads using the link below:
2. Open IIS Manager from cmd by typing inetmgr

3. Create a new website by right clicking your DOMAINPC NAME

4. Create new website in say port port 82 (in most case you may have used port 80)
5.Double Click the site you have created and select Reverse proxy.

6.Check the port of your Development server by debugging your code at visual studio and in my case it is 2529 In reverse proxy window add localhost:2529 as Inbound rule.

7. Now your LAN users can access your development server as http://:82 or port no as you have setup in step 4.For WAN you can NAT (port forward ) your desired port to your PC IP.

Remove Cron Jobs from auth.log

CRON[21587]: pam_unix(cron:session): session opened for user root by (uid=0)
CRON[21587]: pam_unix(cron:session): session closed for user root

This type of logs makes you hard to read the log by you can whe you are looking for information logged by ssh.

To strip off this logs you can simply edit /etc/pam.d/cron (using sudo since you need to root privileges) and comment out the line:

    @include common-session


auth.log Empty

Troubleshooting auth.log empty
/var/log/auth.log can be empty due to various reasons but you can restore rsyslogd with its initial settings so that you get logs

Here is How you reinstall it:

# sudo apt-get remove rsyslog

# sudo apt-get install rsyslog

This will reinstall your rsyslog and you can get the auth logs

auth.log can also be empty when log is rotated. No action is needed in this case.

File Permission for Web Server

We need to change File permission for web server to default for web server securitywe can adjust all web page files by changing directory to web server default directory  and issuing following command as root.

find . -type f -exec chmod 644 {} ;  
find . -type d -exec chmod 755 {} ;

Squid Multiple Outgoing IP

I got lots of queries from Fellow VPS server Administrators on using all of IPs provided by provider for browsing the internet and rotating the IP addresses for squid multiple outgoing ip

When squid server is configured by using following squid acls and tcp_outgoing_address directives we can use all of IPs that are assigned.Here is configuration of  squid multiple outgoing IP address using tcp_outgoing_address

acl myip1 myip
acl myip2 myip
acl myip3 myip

tcp_outgoing_address myip1
tcp_outgoing_address myip2
tcp_outgoing_address myip3

Here I take - as your assigned IP

The acl lines tell squid to match myip which means if someone uses the IP as their proxy server they will match the acl ip1 and so on..

Squid Reverse proxy

We can use squid as a reverse proxy for sharing a public IP with multiple server as well as web acceleration.

Below is the configuration of squid.conf for the purpose of having multiple domains in private IP and that is accessed from the same proxy

# External Port no for squid reverse proxy
http_port 8080 accel vhost

# directive to tell Squid the IP address of the servers are private ip address hosted inside the network
cache_peer parent 80 0 no-query no-digest originserver name=server1
cache_peer parent 80 0 no-query no-digest originserver name=server2
cache_peer parent 80 0 no-query no-digest originserver name=server3

acl sites_server1 dstdomain
acl sites_server2 dstdomain
acl sites_server3 dstdomain

cache_peer_access server1 allow sites_server1
cache_peer_access server2 allow sites_server2
cache_peer_access server3 allow sites_server3

http_access allow sites_server1
http_access allow sites_server2
http_access allow sites_server3

Here 192.168.0.X are internal IPs and are  web address that is routed to corresponding internal websites.

Thanks to :

Script for IP Change Alert

If you need to be notified upon the IP address of the system it can be achieved through following Perl Script

At first a sendemail needs to be installed using :
sudo apt-get install sendemail (in Debian based Distros : Ubuntu )
sudo yum install sendemail (in Redhat Based Distros :Red Hat,Fedora, Cent OS)

Else you may use another MTAs too like sendmail or postfix that is available.

This  IP change alert script alerts the admin if external IP address is changed

#!/usr/bin/perl -w
#Anwesh Tiwari Oct 12 2011

use strict;
my $today=`date +%Y-%m-%d” “%r`;
#location of TEMP file
my $ip_last_check_file = “/home/tmp/IP-Address”;
my $ip_now = `curl -s`;
$ip_now =~ s/.*?(d+.d+.d+.d+).*/$1/s;

open(IP, “<$ip_last_check_file”) or die “Cannot open $ip_last_check_file: $!”;
my $ip_last_check = ;0

if ($ip_now ne $ip_last_check)
open(IP, “>$ip_last_check_file”) or die “Cannot open $ip_last_check: $!”;
print IP $ip_now;
#-s “SMTP address of your SMTP server instead” of “-s localhost” if you dont have ipaddress running.
my $output = `sendemail -f [email protected] -t [email protected] -s localhost -u IP-CHANGE-ALERT -m Gateway IP-address has changed to $ip_now.\\n Event Time :$today`;


Make sure that port 25 is not blocked by ISP

Pending restart SQL server installation

If you  have tried to install SQL Server 2008  and cannot install, because of  the errormessage the prerequistite “Restart the computer is required”.

But every time you restart  computer and try to execute the setup of SQL Server 2008, you get the same message

Then you have change a registry entry in computer

  • Open Regedit
  • Find the key “HKEY_LOCAL_MACHINESYSTEMCurrentControlSetControlSession Manager”
  • Rename the “PendingFileRenameOperations” value to “PendingFileRenameOperations2”
  • Try again

This will solve the Restart Problem

Vsftpd Virtual Users

Installing Vsftpd Virtual Users and Password in text file

vsftpd is a reliable , fast and stable FTP server Daemon. In this article we’ll install the server and make it a  password text file for virtual users allowed to login.

1. Install following  packages using
sudo apt-get install  libpam-pwdfile vsftpd

2. Configure vsftpd (sudo nano /etc/vsftpd.conf)
Following variable need to be changed and leave others to default


local_root  is user’s home directories  in the machine

3. Manage PAM to check the passwd file for users (sudo nano /etc/pam.d/vsftpd)
auth required pwdfile /etc/ftpd.passwd
account required
Remove other configuration from file
4. The passwd file containing the users is created
sudo htpasswd -c /etc/ftpd.passwd user1

Additional users to the file as below:
sudo htpasswd /etc/ftpd.passwd user2

5. Reload vsftpd
sudo /etc/init.d/vsftpd restart

6. User home directory should be created manually  since vsftpd doesn’t do it automatically
sudo mkdir /var/www/user1

7.Appropriate Permissions need to be provided to that folder for user ftp for uploads

chown 775 ftp:ftp /var/www/user1