LinuxBabu ………..

When trying to restart named process after making modifications may end up in a corrupt rndc.key key and the error will show like this:

Sep 12 03:30:54 server named[23683]: /etc/rndc.key:1: configuring key ‘rndc-key’: bad base64 encoding
Sep 12 03:30:54 server named[23683]: loading configuration: bad base64 encoding
Sep 12 03:30:54 server named[23683]: exiting (due to fatal error)

A simple explanation to this is that the key got modified somehow might me some bug.
What to do about this? Well it is simple just check the /etc/rndc.conf file and copy the key from there(you will see the key in the first lines of the file) and replace the key that it is in /etc/rndc.key file and restart named process.

# service named restart
Stopping named: [ OK ]
Starting named: [ OK ]

Make program default editor for a file type

Shift-right-click on a file of a type; this forces the ‘open with’. Click ‘Choose program’, find it, and select the checkbox that tells windows to always open files of this type.

Change IE ‘view source’ program

Folder:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\View Source Editor\Editor Name

has a default key that is the path to a program, e.g.

C:\Program Files\Notepad2\Notepad2.exe

Add to context menu for all files

Run regedit. Create the key:

HKEY_CLASSES_ROOT\*\shell\

…if it doesn’t exist. Choose a name that doesn’t exist under it, e.g. Notepad2, and create that as key, and a key under it called ‘command’:

HKEY_CLASSES_ROOT\*\shell\Notepad2
HKEY_CLASSES_ROOT\*\shell\Notepad2\command

Make the default value under the first what you want to appear in the menu and the second what you want it to run, e.g.

“Edit with Notepad2″
and
“C:\Program Files\Notepad2\Notepad2.exe” “%1″

…respectively.

Q. How do I verify that my ISP or my own recursive resolvers are free from DNS cache poisoning bug that is promised full disclosure of the flaw by Dan on August 7 at the Black Hat conference? How do I test my dns server for DNS cache pollution or DNS Cache Poisoning bug?

A. DNS cache poisoning (also known as DNS cache pollution) is a maliciously created or unintended situation that provides data to a Domain Name Server that did not originate from authoritative DNS sources. It occur if DNS “spoofing attack” has been encountered. An attacker will send malicious data / non-secure data in response to a DNS query. For example dns query for www.linuxbabu.net can be redirected to www.redhat.com.

how do I find out if my DNS server is open to such attack or not?

Visit Dan Kaminsky java script page to check your DNS

You can also use following command dig command, enter:
$ dig +short @{name-server-ip} porttest.dns-oarc.net txt
$ dig +short @ns1.example.com porttest.dns-oarc.net txt
$ dig +short @208.67.222.222 porttest.dns-oarc.net txtSample output:

z.y.x.w.v.u.t.s.r.q.p.o.n.m.l.k.j.i.h.g.f.e.d.c.b.a.pt.dns-oarc.net.
"208.67.222.222 is GOOD: 26 queries in 0.1 seconds from 26 ports with std dev 17746.18"

Another test,
$ dig +short @125.22.47.125 porttest.dns-oarc.net txtOutput:

z.y.x.w.v.u.t.s.r.q.p.o.n.m.l.k.j.i.h.g.f.e.d.c.b.a.pt.dns-oarc.net.
"125.22.47.139 is POOR: 42 queries in 8.4 seconds from 1 ports with std dev 0.00"

FIX :

Run yum update
yum updateOpen named.conf file and comment out following two lines:
query-source port 53;
query-source-v6 port 53;Make sure recursion is limited to your LAN only. Set ACL. Restart bind to take effect:
rndc reload 


service named restart


Hi guys… Today I faced a issue with a new VPS installed with EZ template Centos 5.2. I was preparing the VPS with logwatch, apf and other security and got cron error under roots mail.

Cron errors shows log errors :

/etc/cron.daily/logrotate:

error: stat of /var/log/boot.log failed: No such file or directory
error: stat of /var/log/cron failed: No such file or directory

OR

You do not find log files updating

This was due to the syslog daemon not running. Check if the service is running and restart. Your server may have syslogd daemon on rsyslogd depending on your OS.

I had rsyslogd on Centos 5.2

# /etc/init.d/rsyslog status
rsyslogd is stopped
rklogd is stopped

# /etc/init.d/rsyslog start
Starting system logger: [ OK ]
Starting kernel logger: [ OK ]

Check if the service is being started at the starup :

# chkconfig –list | grep rsyslog
rsyslog 0:off 1:off 2:off 3:off 4:off 5:off 6:off

Use Command to enable the daemon at startup

# chkconfig rsyslog on

The log files were not being created due to the daemons stopped, after restart all started generating.

Cheers!

The following web site will redirect you to a very well written article, which will cover the basics of “Passive vs Active” mode functions.

Active FTP vs. Passive FTP, a Definitive Explanation

After FTP connection has been made, The FTP server will generally choose a random port within a certain range to use and tell the client to connect to, but when the firewall is setup to block this port, the connection can not be made and the client times out. Error example below :

[14:55:16] PASV
[14:55:16] 227 Entering Passive Mode (74,86,43,171,13,209)
[14:55:16] Opening data connection to 74.86.43.171 Port: 3537
[14:55:16] LIST -aL
[14:55:37] A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.

Opening the ports on APF

The first step was to tell APF to have a range of ports open for passive FTP connections. You can put in any range you want as long as it doesn’t conflict with another service. For this we’re going to use the range of 35000-35500.

Will be using vi in this How-To. Please see the Basic Guide to Vim

cd /etc/apf; vi conf.apf

Find IG_UDP_CPORTS   and add passive ports 35000-35500 to look like :

IG_TCP_CPORTS=”20,21,22,25,26,53,80,110,143,161,443,465,623,993,995,2082,2083,2086

,2087,2095,2096,3306,3389,6666,35000_35500“

Save the file and restart APF with

/etc/init.d/apf restart

Setting up the FTP Server (Pure-FTPD):

Now you need to tell PureFTPd to use those ports for passive connections. Open up the file /etc/pure-ftpd.conf in your editor and look for the following.

# PassivePortRange 30000 50000

Two things to note. One, the setting is commented out and two the range doesn’t match what we opened in APF. So change it to the following.

PassivePortRange 35000 35500

Restart the PureFTP server with

/etc/init.d/pure-ftpd restart

Test the connections and your are done !

I need file system quota support for FreeBSD server.

Quick and Dirty How to compile ‘QUOTA’ support for your FreeBSD server.

Please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/quotas.html for more detailed instructions.

To complete the following you will need to have to ssh access to your host server along with full root access.

Login to the remote host via SSH and become root with ‘su -’ then backup your current kernel and ‘/etc’ directory.

cp -Rp /boot/kernel /boot/kernel.good
cp -Rp /etc /etc.good

Now verify you have the correct source code for your server installed in ‘/usr/src’
cd /usr/src
ee UPDATING

Make sure the first displayed date matches your current ‘uname -a’ output.

Once you have confirmed you have the correct source code installed you can then create your custom kernel configuration file.

cd /usr/src/sys/i386/conf
cp GENERIC MYKERNELCONF
ee MYKERNELCONF

Add the line below to your kernel configuration file and then save the file.

## Example Entry for your Kernel Conf ##

options QUOTA # Provide Quota Support

##

Next you will need to build and install your custom kernel.( This step could take a few mins )

cd /usr/src/
make buildkernel KERNCONF=MYKERNELCONF
make installkernel KERNCONF=MYKERNELCONF

Now before you reboot you need to edit 2 files to enable QOUTA support for you file system.

The first is the ‘/etc/rc.conf’ which will we will edit to enable QUOTA support and to also check them on boot.

grep /etc/defaults/quota >> /etc/rc.conf
ee /etc/rc.conf

You will see the following entries at the bottom of the ‘/etc/rc.conf’ file.

enable_quotas=”NO” # turn on quotas on startup (or NO).
check_quotas=”YES” # Check quotas on startup (or NO).

Change both of the entries to “YES” and then save the file.

enable_quotas=”YES” # turn on quotas on startup (or NO).
check_quotas=”YES” # Check quotas on startup (or NO).

Now you need to modify your ‘/etc/fstab’ file to select which slices should have QUOTAS turned on.

Typical ‘/etc/fstab’ file with NO quota support enabled.

# Device Mountpoint FStype Options Dump Pass#
/dev/ad0s1b none swap sw 0 0
/dev/ad0s1a / ufs rw 1 1
/dev/ad0s1f /home ufs rw 2 2
/dev/ad0s1e /usr ufs rw 2 2
/dev/ad0s1d /var ufs rw 2 2

Typical ‘/etc/fstab’ with quota support enabled.

# Device Mountpoint FStype Options Dump Pass#
/dev/ad0s1b none swap sw 0 0
/dev/ad0s1a / ufs rw 1 1
/dev/ad0s1f /home ufs rw,userquota,groupquota 2 2
/dev/ad0s1e /usr ufs rw,userquota,groupquota 2 2
/dev/ad0s1d /var ufs rw 2 2

Now save the ‘/etc/fstab’ file and reboot the host to load the new kernel and remount your drives with full quota support enabled for your server.

reboot

If for some reason your server does not come back up after 2-10 mins from the reboot please contact your support team and let them know you just compiled a custom kernel and may need to have the server booted with the old backup kernel you made earlier. If the server reboots with no problems you should be all set and ready to go with full quota support for your control panel of choice.

How to bind a range of IP’s in Linux
This method is used by Redhat Linux based servers (Centos/RedhatEnterprise/FedoraCore).

Create a file called /etc/sysconfig/network-scripts/ifcfg-eth0-range0
And in the file place these 3 lines but change the IP’s to match YOUR assigned range.

## Start

IPADDR_START=67.18.xxx.xxx
IPADDR_END=67.18.xxx.xxx
CLONENUM_START=0

# Example | IPADDR_START=67.18.333.440
# Example | IPADDR_END=67.18.333.444
# Example | CLONENUM_START=0

## END

The CLONENUM_START should be the number at which the alias interfaces should start. If you add your 5 IP’s to this server and then want to bind a second set of IP’s you create a second file named ‘ifcfg-eth0-range1′ and change the CLONENUM_START to match the last interface alias. IE ‘eth0:5′ = CLONENUM_START=5

After you have created the above file execute the command ‘service network restart’ and your IP’s will be all setup.

*CPANEL NOTE*
Please do not use this method of binding additional IPs if you are using Cpanel. Bind the IPs through the Cpanel interface.

Problem:

I would like to bind all 5 of my usable IP’s to the ‘eth0′ device

Solution:

Just define a new interface in /etc/network interfaces:

## Start
auto eth0
auto eth0:0
auto eth0:1
auto eth0:2
auto eth0:3

iface eth0 inet static
address 192.168.1.2
netmask 255.255.255.248
gateway 192.168.1.1

iface eth0:0 inet static
address 192.168.1.3
netmask 255.255.255.248
gateway 192.168.1.1

iface eth0:1 inet static
address 192.168.1.4
netmask 255.255.255.248

iface eth0:2 inet static
address 192.168.1.5
netmask 255.255.255.248

iface eth0:3 inet static
address 192.168.1.6
netmask 255.255.255.248
## End

Then you can reboot or use the commands below to bring the interfaces up without a reboot.

ifup eth0:0
ifup eth0:1
ifup eth0:2
ifup eth0:3
ifup eth0:4

On the next reboot they should automatically bind to the NIC.

First login to your FreeBSD host as a ‘non-root’ user. You should have an account in the ‘wheel’ group that you can do this with. Once you have logged in run the following commands to switch users to ‘root’

su -
Password:
server#

The prompt should have a # in it now meaning you are the ‘root’ user.

Now run these commands.

ee /etc/rc.conf

Using 192.168.1.3 – 192.168.1.6 as an example

ifconfig_fxp0=”inet 192.168.1.2 netmask 255.255.255.248″
ifconfig_fxp0_alias0=”inet 192.168.1.3 netmask 255.255.255.255″
ifconfig_fxp0_alias1=”inet 192.168.1.4 netmask 255.255.255.255″
ifconfig_fxp0_alias2=”inet 192.168.1.5 netmask 255.255.255.255″
ifconfig_fxp0_alias3=”inet 192.168.1.6 netmask 255.255.255.255″

Note that changes to the ‘_aliasNN’ and also the ‘netmask’ changes to ’255.255.255.255′ from ’255.255.255.248′. The IP’s will not work unless you use a ’255.255.255.255′ netmask for the alias IP’s.

Once you have added the enteries to your file you need to press ‘ESC’ and then select the ‘Save File’ option. You can then reboot the server and the IP’s will be bound and ready to use.

You can also use ‘ifconfig’ on the command line to add them without a reboot.

Please see the following man pages for more information.

man ifconfig
man rc.conf
man netstat

How MySQL Uses Memory
This page lists some of the ways that the mysqld server uses memory, and associated mysqld variable names
Memory Use MySQL 5.0
Memory Use MySQL 4.1

MySQL Optimization which covers:
- Optimization Overview
- Optimizing SELECT and Other Statements
- Locking Issues
- Optimizing Database Structure
- Optimizing the MySQL Server
- Disk Issues
Optimization MySQL 5.0
Optimization MySQL 4.1

MySQL Server Variables – SQL layer or Storage Engine specific.
List some of the more common variables as well as a brief description
Go to article 1
Go to article 2

Optimizing the mysqld variables by Ian Gilfillan
Great article on MySQL optimization, including some guidelines on what you should set mysqld server variable too.
(key_buffer_size, Query cache variables, table_cache, sort_buffer, etc..)
Go to article

Repairing Database Corruption in MySQL by Ian Gilfillan
Table corruption should be rare when using MySQL, however it helps to know how to fix the problem when it does occur.
Go to article

Optimizing MySQL: Queries and Indexes by Ian Gilfillan
The database is just too slow. Queries are queuing up, backlogs growing, users being refused connection. Management is ready to spend millions on “upgrading” to some other system, when the problem is really that MySQL is simply not being used properly. Badly defined or non-existent indexes are one of the primary reasons for poor performance, and fixing these can often lead to phenomenal improvements.
Go to article

Other MySQL Articles by Ian Gilfillan