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Experimentation Platform:
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Intel P4 3.0Ghz (Intel MB)
1 GB RAM
2 x 80 GB HDD on RAID 1 (Disk Mirroring) - alloted entirely to Linux
OS:
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Linux - Redhat Enterprise AS Server v3
Note:
a. I was trying to setup the system so that later on when my server goes online, I don't
have to modify much to make my nameservers work with the internet - so I used my registered domain
"microsys-asia.info" and an internal IP: "10.19.168.5" - as the server IP. In future when my server
goes online, all I've to do is modify this IP and all will be good. So throughout the tutorial
you'll find reference to this domain and the IP used. For your own case, just change to domain to
whatever you feel like and choose a suitable IP to go with.
b. Another standard I've followed is - all console input/output are marked between a pair of CONSOLE tags - they'll appear in a yellow bordered box with black nackground and yellow text.
Make sure the following services are up & running - coz they'll be the ones affected most due to the dns setup:
a. httpd
b. ftpd
c. MTA (Mail Transport Agent) like Postfix, Sendmail etc.
You can see a list of running services using:
CONSOLE
shell> service --status-all | less
Right, lets get to business now.
Once your system is setup and running, either login as "root" or use any other login and use "sudo" to
get root access.
Step 1 - Checking the NIC Card Functionality
Make sure your NIC (Network Interface Card) or Ethernet Card is up and running.
You can check this with -
CONSOLE
shell> ifconfig
This should display information about your primary NIC (called "eth0" and the local loopback interface
called "lo"). It'll be somewhat in the following format:
CONSOLE
eth0 Link encap:Ethernet HWaddr 00:0D:88:39:D2:69
inet addr:10.19.168.5 Bcast:10.19.168.255 Mask:255.255.255.0
inet6 addr: fe80::20d:88ff:fe39:d269/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:24633 errors:0 dropped:0 overruns:0 frame:0
TX packets:32779 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:2843295 (2.7 Mb) TX bytes:3524410 (3.3 Mb)
Interrupt:225 Base address:0xb800
Notice my NIC MAC Address on the first line & my IP and Subnet Mask in the second line.
Step 2 - Configuring the "hosts" file
This file resides in the "/etc" directory and contains the localhost entry (a special entry that must
be present) and any other entries that you care to enter. In fact this file alone can act like a simple DNS,
if you compile a huge list of matching IP and domain names here.
Each entry will take on this form:
"IP address" "Fully Qualified Domain Name (FDQN)" "alias"
The hosts file will look like:
CONSOLE
127.0.0.1 localhost.localdomain localhost
10.19.168.5 getafix.microsys-asia.info getafix
This file should contain at least those two lines - the localhost is a neccessity as well as your
server IP and hostname.domainname. As for the spaces in between the fields make it a point to use ONE
TAB STOP for each.
"getafix" here is the name of my server or its hostname (which you can set using the "hostname"
command - Usage: hostname NameOfYourHost). Alternatively, you can set your hostname by editing a file
called "network" located in the "/etc/sysconfig/" directory.
CONSOLE
NETWORKING=yes
HOSTNAME=”getafix.microsys-asia.info”
Step 3 - Generating a rndc key-pair
Here's what the linux man pages say about "rndc":
QUOTE
rndc controls the operation of a name server. It supersedes the ndc
utility that was provided in old BIND releases. If rndc is invoked with
no command line options or arguments, it prints a short summary of the
supported commands and the available options and their arguments.
rndc communicates with the name server over a TCP connection, sending
commands authenticated with digital signatures. In the current versions
of rndc and named named the only supported authentication algorithm is
HMAC-MD5, which uses a shared secret on each end of the connection.
This provides TSIG-style authentication for the command request and the
name server's response. All commands sent over the channel must be
signed by a key_id known to the server.
utility that was provided in old BIND releases. If rndc is invoked with
no command line options or arguments, it prints a short summary of the
supported commands and the available options and their arguments.
rndc communicates with the name server over a TCP connection, sending
commands authenticated with digital signatures. In the current versions
of rndc and named named the only supported authentication algorithm is
HMAC-MD5, which uses a shared secret on each end of the connection.
This provides TSIG-style authentication for the command request and the
name server's response. All commands sent over the channel must be
signed by a key_id known to the server.
As you can see, the rndc key's are much required to control your nameserver. Here's how to generate
the rndc keys. There's a file called "rndc-confgen" located in the "/usr/sbin/" directory.
Simply run the file "rndc-confgen":
CONSOLE
shell> rndc-confgen
It will give you an output similar to this:
CONSOLE
# controls {
# inet 127.0.0.1 port 953
# allow { 127.0.0.1; } keys { "rndckey"; };
# };
# Start of rndc.conf
key "rndckey" {
algorithm hmac-md5;
secret "RN5xaE0Yr7ar1v0sPugf2g==";
};
options {
default-key "rndckey";
default-server 127.0.0.1;
default-port 953;
};
# End of rndc.conf
# Use with the following in named.conf, adjusting the allow list as needed:
# key "rndckey" {
# algorithm hmac-md5;
# secret "RN5xaE0Yr7ar1v0sPugf2g==";
# };
#
# controls {
# inet 127.0.0.1 port 953
# allow { 127.0.0.1; } keys { "rndckey"; };
# };
# End of named.conf
Carefully notice the "commented out" block of code (the lines with the starting '#') in the SECOND HALF of
the block - from "#Use with the..." till "#End of named.conf". Save this output into another file. You are going
to need it SOON. If you are using a terminallike PuTTY to access your server your can simply drag your mouse over
the desired area and highlight it. Then open a blank file in "vi" and right-click the mouse. That'll paste your
code in the file. Save and exit.
Step 4 - Editing "/etc/named.conf"
We're going to step into some messy editing now. In your "/etc/" folder there is
a file named "named.conf". Open the file in vi or whatever editor you are using.
CONSOLE
shell> vi /etc/named.conf
You're going to face something similar to this:
CONSOLE
options {
directory "/var/named";
// Uncommenting this might help if you have to go through a
// firewall and things are not working out. But you probably
// need to talk to your firewall admin.
// query-source port 53;
};
controls {
inet 127.0.0.1 allow { localhost; } keys { rndc_key; };
};
zone "." {
type hint;
file "named.ca"
};
zone "localhost" IN {
type master;
file "localhost.zone";
allow-update { none; };
};
Between the "option { }" section, after the "directory" clause insert the following:
host-statistics no;
fake-iquery no;
version "Bind"; //This reports just Bind and not it's version to any would be hacker
recursion no;
Now delete the "controls {" clause entirely, and in its place insert the rndc-confgen OUTPUT that
you had earlier saved. Now scroll down below the section titled zone "." { till you reach the ending
brace "};" after the zone "localhost" IN. Make sure you UNCOMMENT the lines starting at key "rndckey" { till the ending brace }; right before # End of rndc.conf.
Put a blank line after it.
Now on a fresh line add in the following:
CONSOLE
zone "microsys-asia.info" IN {
type master;
file "microsys-asia.info.zone";
allow-update { none; };
};
You should put in your own domain in place of "microsys-asia.info" within the quotes after "zone" and between
the quotes after the "file" clause. Make sure you keep the ".zone" part after it.
Below this insert another similar block but with a few modifications:
CONSOLE
zone "168.19.10.in-addr.arpa" IN {
type master;
file "reverse.microsys-asia.info.zone";
allow-update { none; };
};
This is how you figure out what to include after the "zone" between the quotes. Say my IP here is: 10.19.168.5
First, I'd write it backwards i.e. 5.168.19.10 and then chop off the leading 5. leaving me with just
168.19.10. To that I add, .in-addr.arpa giving me a string 168.19.10.in-addr.arpa - which is my
reverse resolution zone. As for the part beside the file clause, you can copy it from the zone above and just add the
word reverse. in front of it. That should do.
Now the last bit of editing for this file.. Check if there are any more zones below this. There should be one like:
CONSOLE
zone "0.0.127.in-addr.arpa" IN {
type master;
file "named.local";
allow-update { none; };
};
Do you notice any similarity here with the zone that you just created ? This is indeed the reverse lookup zone for
your local loopback interface or localhost(127.0.0.1). If this zone is missing from the file, just copy the above section
and paste it - NO MODIFICATIONS NECESSARY.
Besides this, the last line in the file should be:
include "/etc/rndc.key"; - if this line is missing, blindly insert it too.
Now save this file and quit the editor.
Step 5 - Creating the "forward" zone database
Recall the filenames that we specified for our forward and reverse zones in Step 4 ??
file "microsys-asia.info.zone";
file "reverse.microsys-asia.info.zone";
These files must be created for the zones to read them and function properly. They aren't generated by default.
We are going to create these files now. The default directory for the zone files (on a typical linux system) is
"/var/named/" or any directory that was specified as the <DNS ROOT> using the "directory" clause
in the "named.conf" file. If you can't recall scroll back to the beginning of Step 4 and you'll notice it right there:
options {
directory "/var/named";
Anyway, use your editor to create two blank files in the directory "/var/named/" -
a. "microsys-asia.info.zone" &
b. "reverse.microsys-asia.info.zone"
Now open the first file, "microsys-asia.info.zone". Insert the following lines into the file, modifying
wherever necessary and replacing my microsys domain & ip with your own domain and ips.
CONSOLE
$TTL 604800
; Information about "forward" domain microsys-asia.info
$ORIGIN microsys-asia.info.
@ IN SOA ns1.microsys-asia.info. webmaster.microsys-asia.info. (
2004042601 ; serial
86400 ; refresh
7200 ; retry
1209600 ; expiry
604800 ) ; minimum
; Define name servers for this domain
IN NS ns1.microsys-asia.info.
; Define Mail Exchanger for this domain
IN MX 10 mail.microsys-asia.info.
IN A 10.19.168.5
; Define name to address mapping for this domain
ns1 IN A 10.19.168.5
www IN A 10.19.168.5
ftp IN A 10.19.168.5
mail IN A 10.19.168.5
; Loopback domain
localhost IN A 127.0.0.1
One word about this file - notice the trailing dot (".") wherever I've specified a domain name - DO NOT MISS
THE DOTS OUT AT ANY COST - OR THE WHOLE THING WILL COLLAPSE.
In the third line beside, "ns1.microsys-asia.info", notice the "webmaster.microsys-asia.info". This is in
actuality the webmasters email address. Its really webmaster@microsys-asia.info but in here the "@" is
replaced with a "." The numerical values within the paranthesis can be modified suitably. They are mostly
time specifications converted to seconds.
The line:
; Define name servers for this domain
IN NS ns1.microsys-asia.info.
sets up the nameserver for you. It means we are declaring ns1.microsys-asia.info as your nameserver. Don't
forget to replace my domain with yours after the ns1. and don't forget the trailing "." either. If you have more than
one nameservers, insert similar lines below and instead of "ns1." put "ns2." and so on.
Example:
IN NS ns2.microsys-asia.info.
Next is your Mail Exchanger which is utilized by the Mail Transport Agents to forward mails to the correct domain.
; Define Mail Exchanger for this domain
IN MX 10 mail.microsys-asia.info.
The number 10 means we setting a priority of 10 to the mail server. Since we only use one mail server the priority
has no effect.
The next line: IN A 10.19.168.5 The "IN A 192.168.1.200" means we are declaring a host (with no hostname,
so it means microsys-asia.info) and it's IP is 10.19.168.5. Any queries on just microsys-asia.info will resolve to
that IP. Its useful when you configure your web server to load microsys-asia.info OR www.microsys-asia.info.
They both point to the same thing and will return the same web site. If you have an external ISP alloted IP you can
replace this by it to hook your server up to the net. Otherwise, just use your internal IP like me.
The rest of the entries mean we are declaring hosts:
ns1 = ns1.microsys-asia.info
If you have more than one nameserver - it should get listed here along with its ip.
www = www.microsys-asia.info
ftp = ftp.microsys-asia.info
mail = mail.microsys-asia.info
Since they all share the same IP, each of those services will run from the same machine. If you have the mail server
running on a different machine then you should substitute that machines IP address in place of 10.19.168.5.
Now save this file and quit.
Step 6 - Creating the "reverse" zone database
It's time to setup the reverse lookup zone for your IP. Open the blank file "reverse.microsys-asia.info.zone"
that you had created and insert the following lines:
CONSOLE
; Information about "inverse" domain 168.19.10.in-addr.arpa.
@ IN SOA ns1.microsys-asia.info. webmaster.microsys-asia.info. (
2004042601 ; serial (d. adams)
86400 ; refresh
7200 ; retry
1209600 ; expiry
604800 ) ; minimum
; Define name servers for this domain
IN NS ns1.microsys-asia.info.
; Define name to address mapping for this domain
5 IN PTR ns1.microsys-asia.info.
Notice how the IP has been reversed and placed, as I taught you earlier. We had always truncated the last segment ".5"
from the IP before adding it in as the reverse address - that's what is mentioned in the last line - the beginning digit.
If you last IP segment is some other number, replace the 5 in the last line with that.
Now save the file and quit. We are almost done.
Step 7 - Creating the "reverse" zone database for localhost
You don't really have to edit this file - it is created by BIND by default and placed is your DNSROOT, i.e. the
directory containing the zone files, "/var/named/" in this case. Look for a file called "named.local"
It should contain exactly the following lines:
CONSOLE
$TTL 86400
@ IN SOA localhost. root.localhost. (
1997022700 ; Serial
28800 ; Refresh
14400 ; Retry
3600000 ; Expire
86400 ) ; Minimum
IN NS localhost.
1 IN PTR localhost.
If the file is missing - just create one with the same name and insert the lines above. Save and quit.
Step 8 - Editing "/etc/resolv.conf"
Open your editor again and load the file called "resolv.conf" in your "/etc/" directory.
Insert the following lines:
CONSOLE
domain microsys-asia.info
nameserver 10.19.168.5
search microsys-asia.info
Of couse, replace the domain and ip with your own. Notice, only your first nameserver is being specified here and
listed against its IP. The "search" clause tells the server to dig into the system if it can't find the first
nameserver and try to track the other ones. Also if you have more than one nameservers, you should list them serially
here with multiple nameserver clauses, like:
nameserver xx.xx.xx.xx
nameserver yy.yy.yy.yy
nameserver zz.zz.zz.zz and so on...
Save and quit.
Step 9 - Restarting "named" or the DNS Server
We are more or less done. All that remains now is to restart the name daemon to load the modified configuraiton
info. Execute the following command:
CONSOLE
shell> service named restart
Alternatively, you can use: /etc/rc.d/init.d/named restart
You should see something like:
CONSOLE
Stopping named: [ OK ]
Starting named: [ OK ]
If you see bthis - we are ALL SET and ready to go. If you get an error message saying, "rndc: connect failed:
connection refused", IGNORE. It doesn't really matter till you are hooked onto the outside world.
Step 10 - Final Step: Check your nameserver
Use the tools named "nslookup" and/or "dig" to check if your nameserver is resolving properly.
CONSOLE
shell> dig microsys-asia.info
OR
shell> nslookup microsys-asia.info
On my system, dig reports:
CONSOLE
shell> dig microsys-asia.info
; <<>> DiG 9.2.3 <<>> microsys-asia.info
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 21513
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;microsys-asia.info. IN A
;; Query time: 1 msec
;; SERVER: 10.19.168.5#53(10.19.168.5)
;; WHEN: Thu Feb 3 03:12:27 2005
;; MSG SIZE rcvd: 36
This means all is WELL
and we are DONE. Have fun and if you need clarifications on any part, please don't hesitate to post here and I'll try to make suitable
ammends to the tutorial and reply to your posts as well.
Best of luck & Cheers
