Ayad knowledge base

By default CentOS does not support the ‘NTFS’ file system, if you are tying to mount an NTFS file system  you will  need to have installed correct RPM package

#  wget  packages.sw.be/rpmforge-release/rpmforge-release-0.3.6-1.el5.rf.i386.rpm

# rpm -Uhv rpmforge-release-0.3.6-1.el5.rf.i386.rpm

warning: rpmforge-release-0.3.6-1.el5.rf.i386.rpm: Header V3 DSA signature: NOKEY, key ID 6b8d79e6
Preparing…        ########################################### [100%]
1:rpmforge-release  ########################################### [100%]

#  yum install fuse fuse-ntfs-3g dkms dkms-fuse

Make a directory for mount a file system to /mnt/usb

# mkdir /mnt/usb

# fdisk -l

Disk /dev/sda: 1999.8 GB, 1999844147200 bytes
255 heads, 63 sectors/track, 243133 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          64      514048+  83  Linux
/dev/sda5           14902       15921     8193118+  83  Linux
/dev/sda6           15922      243133  1825080358+  83  Linux

Disk /dev/sdb: 1000.2 GB, 1000204885504 bytes
255 heads, 63 sectors/track, 121601 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1      121602   976759808    7  HPFS/NTFS

Execute the mount command

# mount -t ntfs-3g /dev/sdb1 /mnt/usb/

Open the mounted directory /mnt/usb

# cd /mnt/usb/

# ls -al
drwxr-xr-x 39 root root       4096 May 11 09:34 .
drwxr-xr-x  5 root root       4096 Jan 11 09:34 ..

Now the ntfs partition mounts perfect.

#  df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda6             1.1T  179G  880G  12% /
/dev/sda5             6.6G  146M  6.1G   2% /tmp
/dev/sda1             587M   43M  519M  10% /boot
/dev/sdb1             932G  781M  931G   1% /mnt/usb

You will need to unmount the partition,

umount /mnt/usb

references

http://thelinuxfaq.com/41-mount-unknown-file-system-type-ntfs-centos

OpenSSH Installations under CentOS Linux

To install the server and client type:

# yum -y install openssh-server openssh-clients

Start the service:

# chkconfig sshd on
# service sshd start

Make sure port 22 is opened:

netstat -tulpn | grep :22

Firewall Settings

Edit /etc/sysconfig/iptables (IPv4 firewall),

vi /etc/sysconfig/iptables

Add the line

-A RH-Firewall-1-INPUT -m state –state NEW -m tcp -p tcp –dport 22 -j ACCEP

If you want to restict access to 192.168.1.0/24, edit it as follows:
-A RH-Firewall-1-INPUT -s 192.168.1.0/24 -m state --state NEW -p tcp --dport 22 -j ACCEPT

If your site uses IPv6, and you are editing ip6tables, use the line:
-A RH-Firewall-1-INPUT -m tcp -p tcp --dport 22 -j ACCEPT

Save and close the file. Restart iptables:
# service iptables restart

———————-

OpenSSH Server Configuration

Edit /etc/ssh/sshd_config, enter:
# vi /etc/ssh/sshd_config

To disable root logins, edit or add as follows:
PermitRootLogin no

Restrict login to user tom and jerry only over ssh:
AllowUsers tom jerry

Change ssh port i.e. run it on a non-standard port like 1235
Port 1235

Save and close the file. Restart sshd:
# service sshd restart

vzctl set VEID –hostname VEID.domain.local –save

if in single file

sed -i ‘s/ugly/beautiful/g’ /home/bruno/old-friends/sue.txt

if in multiple files

$ find /home/bruno/old-friends -type f -exec sed -i ‘s/ugly/beautiful/g’ {} \;

Thanks.

SSH to the server and run the following command

grep pro /proc/cpuinfo -c

Thanks.

The two directives are PORTFLOOD and SYNFLOOD.
SYNFLOOD

SYNFLOOD is disabled by default. If you are not receiving any sort of attack, there is no need to enable it. If you are expecting an attack, enable it and set the rules a bit strict, like

SYNFLOOD = “1?

SYNFLOOD_RATE = “30/s”

SYNFLOOD_BURST = “10?

i.e. if 30 connections are received from an IP/sec for 10 times, block it. Make sure don’t keep it too strict if you are not receiving an attack else it will generate false positives and will block legit connections.
PORTFLOOD

PORTFLOOD = 80;tcp;100;5,22;tcp;5;300

ie, If an IP makes 100 connections in 5 sec to port 80 (tcp), then it will be blocked from the server and if 5 connections in 300 sec to 22 port.

if you got the above error in plesk, you need to do the following steps to solve the issue

1- update windows

2- restart the server

3- run the following command

cd %plesk_bin%

ai.exe –select-product-id panel  –select-release-current –reinstall-patch –install-component base

Thanks.

Doing the following seems gets rid of it until the next time cpanel is upgraded or until the next time apache is compiled.

Edit /var/cpanel/templates/apache2/main.default

Delete…

————

[% IF file_test('f', '/usr/local/cpanel/bin/leechprotect') -%]
RewriteEngine on
RewriteMap LeechProtect prg:/usr/local/cpanel/bin/leechprotect
RewriteLock /usr/local/apache/logs/rewrite_lock
[% END -%]
--------

Edit /usr/local/apache/conf/httpd.conf 

Delete ...
-----------

RewriteEngine on
RewriteMap LeechProtect prg:/usr/local/cpanel/bin/leechprotect
RewriteLock /usr/local/apache/logs/rewrite_lock
-----------

Kill the leachprotect process.


Run /usr/local/cpanel/bin/apache_conf_distiller --update

service httpd restart

# mdadm /dev/md0 -f /dev/sda1                                  stop the rebuild
mdadm: set /dev/sda1 faulty in /dev/md0
# mdadm /dev/md0 -r /dev/sda1                                  remove the devise to avoid start rebuild again after reboot
mdadm: hot removed /dev/sda1
# mdadm /dev/md0 -a /dev/sda1                                     to start rebuild 
mdadm: hot added /dev/sda1

in WHM -> Exim Configuration -> Advanced Editor

Add the following in the first box:

================================================================

received_header_text = Received: ${if def:sender_rcvhost {from ${if def:authenticated_id {localhost}{$sender_rcvhost}}\n\t}{${if def:sender_ident {from ${quote_local_part:$sender_ident} }}}}by $primary_hostname ${if def:received_protocol {with $received_protcol}} ${if def:tls_cipher {($tls_cipher)\n\t}}(Exim $version_number)\n\t${if def:sender_address {(envelope-from <$sender_address>)\n\t}}id $message_exim_id${if def:received_for {\n\tfor $received_for}}

================================================================

If the message is from an authenticated user, it will display “localhost” instead of the senders home ip address, thus resolving the issue.

Thanks.