Php commands, errors, information, news, education

bind/named : network unreachable resolving (IPv6)

admin — Tue, 03 Aug 2010 07:30:31 +0000

RH 5.4 update: bind/named : network unreachable resolving (IPv6)

The new bind version 9.3.6 (Redhat 5.4) try to use IPv6 transport even if the server host does not have IPv6 connectivity, resulting in slower name resolution.

Quote:

Sep 2 19:43:16 cpanel named[22767]: network unreachable resolving ‘ns.isc.afilias-nst.info/A/IN’: 2001:500:7::79#53

To fix this you have to start the bind damon with “-4″ (IPv4 only). You can add the line “OPTIONS=”-4″” to /etc/sysconfig/named to do so.

PHP Error Class ‘SoapClient’ not found

admin — Thu, 24 Jun 2010 07:22:47 +0000

I’ve often found that something gets left out or forgotten when moving a website from an old server to a new install. I’ve just finished migrating one of my customer’s sites to a new CentOS 5.0 install with Apache 2.2 and PHP 5.1.6, and there’s one single PHP script in the site which uses the SoapClient class.

Naturally I’d forgotten to test this particular function until after the migration was complete, and was wondering why the script had failed. A quick look in the Apache error log file revealed the following error message:

 [Wed Sep 25 00:50:12 2007] PHP Fatal error:  Class 'SoapClient' not found in /path/test.php on line ...

Aha! I'd forgotten to install the SOAP extension when I'd installed PHP on this particular CentOS machine. Not being to sure what the package would be called, I did this:

yum search soap | grep php

which returned the following:


php-soap.x86_64                          5.1.6-5.el5            base
php-soap
The php-soap package contains a dynamic shared object that will add
php-soap.x86_64                          5.1.6-11.el5           updates
php-soap
The php-soap package contains a dynamic shared object that will add
php-soap.x86_64                          5.1.6-7.el5            updates
php-soap
The php-soap package contains a dynamic shared object that will add
php-soap.x86_64                          5.1.6-12.el5           updates
php-soap
The php-soap package contains a dynamic shared object that will add
php-soap.x86_64                          5.1.6-15.el5           updates
php-soap
The php-soap package contains a dynamic shared object that will add
php-soap.x86_64                          5.1.6-15.el5           updates
php-soap
The php-soap package contains a dynamic shared object that will add
So that tells me I need to install the "php-soap" package; pretty straight forward name which I should have been able to guess...
$ yum install php-soap

=============================================================================
 Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
 php-soap                x86_64     5.1.6-15.el5     updates           135 k
Updating for dependencies:
 php                     x86_64     5.1.6-15.el5     updates           1.2 M
 php-cli                 x86_64     5.1.6-15.el5     updates           2.3 M
 php-common              x86_64     5.1.6-15.el5     updates           139 k
 php-devel               x86_64     5.1.6-15.el5     updates           511 k
 php-gd                  x86_64     5.1.6-15.el5     updates           112 k
 php-imap                x86_64     5.1.6-15.el5     updates            52 k
 php-mbstring            x86_64     5.1.6-15.el5     updates           975 k
 php-mysql               x86_64     5.1.6-15.el5     updates            86 k
 php-pdo                 x86_64     5.1.6-15.el5     updates            62 k
 php-xml                 x86_64     5.1.6-15.el5     updates            98 k

Transaction Summary
=============================================================================
Install      1 Package(s)
Update      10 Package(s)
Remove       0 Package(s)

Total download size: 5.6 MB
Is this ok [y/N]:
As you can see, there were also some updates to some of the PHP packages I had already installed, so these were installed at the same time. After the install was complete, it was just a matter of restarting Apache and the SoapClient class could now be used by my PHP script.

Using YUM to install software can be done on CentOS, Red Hat Enterprise Linux, Fedora and some other Linux distributions. Others may use different package managers and call the packages different names, so the method of installing PHP SOAP will be different from Linux distribution to Linux distribution.

Issues related to the DNS server for Linux

admin — Wed, 12 May 2010 07:54:40 +0000

IMPORTANT: Do not ignore this email.
The hostname resolves to . It should resolve to (ip address). Please be sure to correct /etc/hosts as well as the ‘A’ entry in zone file for the domain.

Some are all of these problems can be caused by
/etc/resolv.conf being setup incorrectly. Please check this file if you
believe everything else is correct.

You may be able to
automatically correct this problem by using the ‘ Add an A entry for your
hostname ‘ under ‘ Dns Functions ‘ in your Web Host Manager

Solution :

1) root WHM panel “Change Hostname” enter the hostname, and what there is to learn (eg sunucuadi.domainadi.com yaziyor get there.)

2) root WHM panel “Edit DNS Zone” Click on the drop-down list domainadi.com ‘if u find below and choose “Edit” button you

3) at the bottom of the drop in the “Add New Entries Below this Line”, the first blank box under the servername’re writing. 14 400 is not just the box. Select from the selection box that says the letter “A” are selected. When it comes to the side than a box to box, our server’s main IP address that you entered. After you have pressed the Save button.

Dns server to restart after this operation is required.

How to Clear and Delete Last Logged In Users and Bad Login Attemps Log (wtmp and btmp)

admin — Fri, 07 May 2010 07:31:07 +0000

In Linux and Unix operating system, it’s possible to use “last” command to display and show the last logged in (and out) users history, and “lastb” command to show and display all the bad login attempts. The users’ login history is been logged and saved in wtmp file while faild login attempts is been stored in btmp file, both files usually located in /var/log directory.

The logging of information into wtmp and btmp is continuous, and can potentially make the wtmp and btmp files grow very to a very big size. The situation is especially true to btmp, which logs failed or bad login attemps to the system, if the administrator does not disable FTP or SSH password authentication, and the server is been attacked via brute-force breaking in attempts, where any wrong user name or incorrect password been logged to btmp.

In addition, administrator may also want to clear and erase the history of login history once in a while. Or, system that running low or almost running out of disk space on /var may want to purge and delete the wtmp and btmp to reclaim and save some disk space.

In any case, the proper way to clear and reset wtmp and btmp files is by piping a blank input to the file, overwriting and replace all existing content. The command that can be used has the syntax like below:

cat /dev/null > /var/log/wtmp

or, on some system, simply like below:

> /var/log/wtmp

Note: Change the path and file name (i.e. btmp) accordingly.

Above commands will remove, clear and empty the content of the btmp or wtmp files, allowing new information to be started logging afresh again. The file is not been deleted or erased, and is leaved intact, as the btmp and wtmp files will not be recreated when not found. The system only logs information into these files if they are present.

Tip: For people who has already deleted the wtmp and btmp files, just re-create the file by touch command, and assign a proper permissions to the file (-rw-rw-r– root utmp or -rw—— root utmp btmp), or else “Excess permission or bad ownership on file /var/log/btmp or /var/log/wtmp” may occur.

Note that there may be files named as wtmp.1, wtmp.2 wtmp.3, wtmp.4, btmp.1, btmp.2, btmp.3, btmp.4, which are the backup archives, and can be safely removed or deleted.

How to Read /var/log/btmp, Rotate the btmp Log With Logrotate

admin — Fri, 07 May 2010 07:23:41 +0000

The btmp log keeps track of failed login attempts. I have seen on a default linux setup with logrotate configured where the btmp log is left out of rotation and eventually grows out of hand. So first you want to make sure that the btmp log is rotated using logrotate with the below information.

Log Location:/var/log/btmp, /var/log/wtmp

To rotate the btmp log add the below to the logrotate.conf file located in the /etc directory.

Addition to logrotate.conf for btmp:

/var/log/btmp {
monthly
minsize 1M
create 0600 root utmp
rotate 1
}

You can change the amount of archived files you keep by modifying the number after rotate. Make sure that the “create 0600 root utmp” statement is in this configuration as the btmp file can be used by crackers to gain access to your server. One of the more common mistakes when logging into a server is typing the password instead of the username so crackers could possibly gain access by reading the btmp log file.

If you want to read the list of failed login attempts to look for patterns to help make your server more secure then use the command below.

How to Read btmp Log:

`1`	`last -f /var/log/btmp`

This will provide an output like the below.

Example btmp Entries:

stive ssh:notty 133.130.202.148 Thu Jul 5 06:02 – 06:02 (00:00)
evo ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:02 (00:00)
admin ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:01 (00:00)
evren ssh:notty 133.130.202.148 Thu Jul 2506:01 – 06:01 (00:00)
usta ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:01 (00:00)
sakki ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:01 (00:00)
user ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:01 (00:00)
kanis ssh:notty 133.130.202.148 Thu Jul 5 06:01 – 06:01 (00:00)
As you can see the 133.130.202.148 address is running some type of brute force against this server in an attempt to gain access. Now you could add this IP address to your iptables or other firewall to defend against such an attack.