Posts Tagged ‘server1’

How to configure equivalent of Linux /etc/resolv.conf search domain.com in MS Windows – DNS Suffix

Thursday, June 26th, 2014

windows-append-dns-suffixes-on-windows-equivalent-of-linux-search-in-resolv-conf-screenshot

Linux's default file that defines what DNS servers will be used /etc/resolv.conf typically contains directives with the default search domain or domains; used for FQDN (Fully Qualified Domain Name) completion when no domain suffix is supplied as part of the  DNS query. Lets say sub-domains under domain.com  has to be accessed (in /etc/resolv.conf) there is:

search domain.com

That is very handy whether you have to ssh or open in web browser (sites) or multiple servers each residing under a single main domain name (for example:
server1.domain.com, server2.domain.com, server3.domain.com etc.) by typing in browser or SSH by only passing the sub-domain name i.e.:
 

http://server1
http://server2

or

ssh user@server1
ssh user@server2


Here is /etc/resolv.conf from pc-freak.net

# cat /etc/resolv.conf

domain pc-freak.net
search pc-freak.net bergon.net

 

Here is example of what I mean, ascii-games is a sub-domain of pc-freak.net (ascii-games.pc-freak.net) and is resolved with no need to type full FQDN

 

# host ascii-games
ascii-games.pc-freak.net has address 83.228.93.76


The DNS server knows that all failed to resolve queries by set DNS should be searched (resolved) under the defined search domain, i.e. each DNS query for server2, serverX (would try to be resolved as a subdomain of domain.com).

Therefore, a very good question is what is Microsoft Windows (2000, 2003, 8) OS equivalent way to define search domain.com into /etc/resolv.conf?

In Windows the same /etc/resolv.conf hosts search is done using the so called "DNS Suffixes".

DNS Suffixes are used for resolv of (domain name strings with no dots).

Adding a new DNS Suffix in Windows is done from

windows-control-panel-network-connections-screeshot-add-dns-suffix-equivalent-to-linux-resolv-conf-search

 

Control Panel -> Network and Sharing Center -> Change Adapter Settings

 

Here select LAN card Adapter used to bring Internet to Win host,be it Local Area Connection or

Wireless Network Connection

 and choose:

Properties


windows-append-dns-suffixes-on-windows-equivalent-of-linux-search-in-resolv-conf-screenshot

 

 

From

Network Connection Properties

dialog select

Internet Protocol Version 4 (TCP/IPv4)

and again click on

Properties

 


network-properties-internet-protocol-version4_tcp_ipv4-windows-settings-screenshot-advanced-tab-add-dns-suffix

On next dialog click on

 

Advanced (button) -> DNS (tab)

windows-append-dns-suffixes-on-windows-equivalent-of-linux-search-in-resolv-conf-screenshot


In field
 

DNS Suffix for this connection

fill in host which you would like to resolve with no need for FQDN and press the

Add


(exactly like adding search pc-freak.net in  /etc/resolv.conf on Linux host). Add multiple hosts DNS Suffix, if you want to access subdomains naming from multiple base domain.

How to copy / clone installed packages from one Debian server to another

Friday, April 13th, 2012

1. Dump all installed server packages from Debian Linux server1

First it is necessery to dump a list of all installed packages on the server from which the intalled deb packages 'selection' will be replicated.

debian-server1:~# dpkg --get-selections \* > packages.txt

The format of the produced packages.txt file will have only two columns, in column1 there will be the package (name) installed and in column 2, the status of the package e.g.: install or deinstall

Note that you can only use the –get-selections as root superuser, trying to run it with non-privileged user I got:

hipo@server1:~$ dpkg --set-selections > packages.txt
dpkg: operation requires read/write access to dpkg status area

2. Copy packages.txt file containing the installed deb packages from server1 to server2

There is many way to copy the packages.txt package description file, one can use ftp, sftp, scp, rsync … lftp or even copy it via wget if placed in some Apache directory on server1.

A quick and convenient way to copy the file from Debian server1 to server2 is with scp as it can also be used easily for an automated script to do the packages.txt file copying (if for instance you have to implement package cloning on multiple Debian Linux servers).

root@debian-server1:~# scp ./packages.txt hipo@server-hostname2:~/packages.txt
The authenticity of host '83.170.97.153 (83.170.97.153)' can't be established. RSA key fingerprint is 38:da:2a:79:ad:38:5b:64:9e:8b:b4:81:09:cd:94:d4. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '83.170.97.153' (RSA) to the list of known hosts. hipo@83.170.97.153's password:
packages.txt

As this is the first time I make connection to server2 from server1, I'm prompted to accept the host RSA unique fingerprint.

3. Install the copied selection from server1 on server2 with apt-get or dselect

debian-server2:/home/hipo# apt-get update
...
debian-server2:/home/hipo# apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
debian-server2:/home/hipo# dpkg --set-selections < packages.txt
debian-server2:/home/hipo# apt-get -u dselect-upgrade --yes

The first apt-get update command assures the server will have the latest version of the packages currently installed, this will save you from running an outdated versions of the installed packages on debian-server2

Bear in mind that using apt-get sometimes, might create dependency issues. This is depending on the exact package names, being replicated in between the servers

Therefore it is better to use another approach with bash for loop to "replicate" installed packages between two servers, like so:

debian-server2:/home/hipo# for i in $(cat packages.txt |awk '{ print $1 }'); do aptitude install $i; done

If you want to automate the questioning about aptitude operations pass on the -y

debian-server2:/home/hipo# for i in $(cat packages.txt |awk '{ print $1 }'); do aptitude -y install $i; done

Be cautious if the -y is passed as sometimes some packages might be removed from the server to resolve dependency issues, if you need this packages you will have to again install them manually.

4. Mirroring package selection from server1 to server2 using one liner

A quick one liner, that does replicate a set of preselected packages from server1 to server2 is also possible with either a combination of apt, ssh, awk and dpkg or with ssh + dpkg + dselect :

a) One-liner code with apt-get unifying the installed packages between 2 or more servers

debian-server2:~# apt-get --yes install `ssh root@debian-server1 "dpkg -l | grep -E ^ii" | awk '{print $2}'`
...

If it is necessery to install on more than just debian-server2, copy paste the above code to all servers you want to have identical installed packages as with debian-server1 or use a shor for loop to run the commands for each and every host of multiple servers group.

In some cases it might be better to use dselect instead as in some situations using apt-get might not correctly solve the package dependencies, if encountering problems with dependencies better run:

debian-server2:/home/hipo# ssh root@debian-server1 'dpkg --get-selections' | dpkg --set-selections && dselect install

As you can see using this second dselect installed "package" mirroring is also way easier to read and understand than the prior "cryptic" method with apt-get, hence I personally think using dselect method is a better.

Well that's basically it. If you need to synchronize also configurations, either an rsync/scp shell script, should be used with all defined server1 config files or in case if a cloning of packages between identical server machines is necessery dd or some other tool like Norton Ghost could be used.
Hope this helps, someone.