NS Lookup
# nslookup > set querytype=soa > stackoverflow.com Server: 217.30.180.230 Address: 217.30.180.230#53
Windows Services can sometimes have a nasty habit of getting stuck in the stopping or starting state. Some believe that at this point there is no alternative but to reboot the server to clear the problem.
However, the following trick usually will work.
The first step is to right click and select Properties on the offending Windows Service in order to find the actual Service Name.
Ex: Services > Microsoft FTP service
Start > Administrative Tools > Services
The next step is to do an sc queryex on the Windows Service in order to find the Process ID.
sc queryex ftpvc
The Process ID is 5180. So now we can issue the taskkill /F command on the process.
taskkill /PID 6524 /F
Another thing to remember: in Windows 2008, if we are not running the command prompt with ‘run as administrator’, we will get an access denied error on the delete.
Is you Horde email failing due to file size attachments? Check the php.ini file in horde:
[root@server ~]# grep upload_max_filesize /etc/psa-webmail/horde/horde/php.ini upload_max_filesize = 5M
Now edit the file:
[root@server ~]# nano /etc/psa-webmail/horde/horde/php.ini
upload_max_filesize = 5M
Change to required value
upload_max_filesize = 128M
Save and exit and restart horde
SERVICE HORDE RESTART
Now check the php config file – php.ini for max_uploads and max_post
grep max_file_uploads /etc/php.ini
max_file_uploads = 99999
To Create and Register Your Domain Hosts in Parallels Plesk Panel
Log in to Parallels Plesk Panel as an administrator.
Go to the Websites & Domains tab, and then click DNS Settings.
For the row with the Record Type of NS, click your domain name, change the following, and then click OK:
Record type — NS.
Domain Name — Leave this field.
Name server — Type ns1.coolexample.com, where coolexample.com is your domain name.
For the row with the Host of ns.coolexample.com, where coolexample.com is your domain, click it, change the following, and then click OK:
Record type — A.
Domain Name — Type ns1.
IP Address — Enter your server’s IP address.
Click Add Record, complete the following fields, and then click OK:
Record type — Select NS.
Domain Name — Leave this field blank.
Name server — Enter ns2.coolexample.com, where coolexample.com is your domain name.
Click Add Record, complete the following fields, and then click OK:
Record type — Select A.
Domain Name — Type ns2.
IP Address — Enter your server’s IP address
Click Update.
Go to the Server tab in Plesk, and then, from the Server Management section, click Services Management.
Next to DNS Server (BIND), click Refresh. Allow a few minutes for the service to restart.
Curl can be helpful in testing many things including web sites.
See if curl is installed
Using ssh:
[root@localhost root]# which curl
This will tell you if the system has curl installed. But you need to have libcurl, and the curl PHP extension to be able to use curl in PHP. To see if it’s enabled, simply do:
phpinfo();
in a PHP file, and see what it outputs. It will list all active extensions (and some more info). CTRL-F for curl in that output.
Check a site load time:
time curl -s http://www.coldriverdata.com > /dev/null
Output:
real 0m0.191s user 0m0.004s sys 0m0.000s
Stress test a Site:
The Curl syntax allows you to specify sequences and sets of URL’s. Say for example we’re going to run a load stress test against this site we can run…
curl -s "http://coldriverdata.com?[1-1000]"
This will make 1000 calls to coldriverdata.com i.e.
http://coldriverdata.com?1
http://coldriverdata.com?2
http://coldriverdata.com?3
…
http://coldriverdata.com?1000
So say you want to stress test your web application and it won’t complain if it’s fed an extra parameter, 10,000 calls could be done something like.
curl -s "http://yourappp.com/your_page_to_test.php?[1-10000]"
Multiple Pages
Easy just add each page to the command line.
curl -s "http://yourapp.com/page1.php?[1-1000]" "http://yourappp.com/page2.php?[1-1000]"
Or even…
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]"
Timing
Using the time command we can get a view on our performance
time curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]"
real 0m0.606s
user 0m0.009s
sys 0m0.008s
Simulating consecutive users
OK, this is great for sending a whole bunch of calls one after the other but what about simultaneous calls. For this we can place the Curl calls in a script and set them running in the background. i.e. my_stress_test.sh
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
curl -s "http://yourapp.com/page{1, 2}.php?[1-1000]" &
pidlist="$pidlist $!"
for job in $pidlist do
echo $job
wait $job || let "FAIL+=1"
done
if [ "$FAIL" == "0" ]; then
echo "SUCCESS!"
else
echo "EPICFAIL! ($FAIL)"
fi
Then run
time my_stress_test.sh
NOTE:
This does not simulate user behaviour exactly as the browser is not only downloading the page but all attached images, javascripts, stylesheet etc. You could simulate this too by adding the URL’s to the url command.
Find file owned by a group
Use the following syntax:find directory-location -group {group-name} -name {file-name}
Where,
- directory-location : Locate the file in this directory path.
- -group {group-name} : Find the file belongs to group-name.
- -name {file-name} : The file name or a search pattern
In this example, locate or find all files belongs to a group called “ftpusers” in the /home directory:
# find /home -group ftpusers
To find all *.c file belongs to a group called “ftpusers” in /data/project directory, run:
# find /data/project -group ftpusers -name "*.c"
OR do case insensitive search:
# find /data/project -group ftpusers -iname "*.c" Find file owned by user
The syntax is: find directory-location -user {username} -name {file-name}
Where,
- directory-location : Locate files or directories in this directory location.
- -user { user-name } : Find the file belongs to user.
- -name {file-name} : File name or pattern.
In this example, locate or find all file belongs to a user called “vivek” in /var directory:
# find /var -user vivek
To find all *.pl (perl files) file belongs to a user called “vivek” in /var/www directory, enter:
# find /var/www -user vivek -name "*.pl"
Want to change the ssh port for ssh? Here is a good tutorial.
(Note: If you are making these changes – ssh to the server and keep the terminal open as you make the changes. Test with a new terminal. This way if something is amiss – you are not locked out.)
Edit /etc/ssh/sshd_config, enter:
# vi /etc/ssh/sshd_config
Note:
The strategy used for options in the default sshd_config shipped with OpenSSH is to specify options with their default value where possible, but leave them commented. Uncommented options change a default value.
Uncomment the following and edit to set the port to 10221:
Port 10221
ListenAddress option
Note: If you have multiple IP address on the server, add you IP addresses.
ListenAddress as follows :
## bind sshd to two ip address on a non-standard port ## ListenAddress 192.168.1.5:10221 ListenAddress 203.1.2.3:10221
Save and close the file.
Before you restart or reload sshd server. You need to update SELinux configuration or Firewall settings (iptables).
You also need to update firewall settings so that users can login using TCP # 10221. Edit,
/etc/sysconfig/iptables and open sshd port 10221: # vi /etc/sysconfig/iptables
Edit/append as follows:
## delete or comment out port 22 line ## ## -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT ## open port 22 -A INPUT -m state --state NEW -m tcp -p tcp --dport 10221 -j ACCEPT
Save and close the file. If you are using IPv6, edit /etc/sysconfig/ip6tables file too. Temporally, stop the firewall so that you will not loose the connectivity to the server:
# service iptables stop # service ip6tables stop
Restart sshd on a CentOS
# service sshd restart
Verify new port settings with the following netstat command:
# netstat -tulpn | grep sshd
Finally, start the firewall:
# service iptables start ## IPv6 ## # service ip6tables start
Now, login with a different terminal to check the settings.
Your server is running very slow.
Top looks Okay. Loads are not insane. Ram is high, but not out of bounds. sar shows high i/o wait times. Swap usage is not an issue. MySql process show hundreds of sleeping processes. Restarting MySql or Apache clears them, but then they start right back up.
WHAT? This make no sense!
tail /var/www/vhost/domain.com/statistics/log/access_log
…
[07/Dec/2013:17:08:17 -0700] “GET /local/image_product480000_1/mlomeupenvtb2012tb201212tb201212044071d032736e44d9b3e5b914d378f9e2jpg.jpg HTTP/1.0″ 200 16322 “-” “-”
[07/Dec/2013:17:08:17 -0700] “GET /local/image_product480000_1/pics2dsstaticcomprodimg165178300jpg.jpg HTTP/1.0″ 200 12690 “-” “-”
[07/Dec/2013:17:08:17 -0700] “GET /local/image_product480000_1/slimagesmacyscomisimageMCYproducts4optimized515264fpxtif.jpg HTTP/1.0″ 200 10497 “-” “-”
[07/Dec/2013:17:08:17 -0700] “GET /local/image_product480000_1/plefuxcom6120111219A0361000WNipadiphonebatteriesexternal5000mah3751965bigjpg.jpg HTTP/1.0″ 200 9638 “-” “-”
[07/Dec/2013:17:08:17 -0700] “GET /local/image_product480000_1/taylorgiftscomimagesp43126500jpg.jpg HTTP/1.0″ 200 59977 “-” “-”
Notice how these connections are coming from the server itself instead of from an external IP.
Now look at who is connecting to the server:
netstat -nat | grep :80 | gawk '{ print $5; }' | gawk -F: '{ print $1 }' | sort | uniq -c | sort -n
2 66.249.73.222
3 157.55.32.143
3 199.30.20.68
3 199.30.20.76
4 131.253.24.85
4 199.30.20.106
4 23.67.252.11
4 65.55.55.229
5 174.125.28.4
12 23.67.252.59
325 64.150.184.165
Again, all coming from the server. The solution to the problem was discovered in /tmp
ls -la /tmp
total 44532
drwxrwxrwx 4 root root 3522560 Dec 7 17:12 .
drwxr-xr-x 24 root root 4096 Dec 6 13:03 ..
drwx–x–x 2 apache apache 4096 Feb 29 2012 .bash
-rw-r–r– 1 apache apache 37281 Oct 13 10:21 .dsf
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.1
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.2
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.3
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.4
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.5
-rw-r–r– 1 apache apache 37287 Oct 13 17:46 .dsf.6
-rw-r–r– 1 apache apache 37281 Oct 13 18:18 .dsf.7
-rw-r–r– 1 apache apache 37281 Oct 13 18:18 .dsf.8
now,
ls -la /tmp/.bash
total 27392
drwx–x–x 2 apache apache 4096 Feb 29 2012 .
drwxrwxrwx 4 root root 3522560 Dec 7 17:14 ..
-rwx–x–x 1 apache apache 146 Nov 12 2012 1
-rwxr-xr-x 1 apache apache 323 Jan 13 2011 autorun
-rwx–x–x 1 apache apache 8922 Jan 23 2006 b
-rwx–x–x 1 apache apache 19557 May 9 2005 b2
-rwxr-xr-x 1 apache apache 11445 Jan 5 2011 bang
-rwxr-xr-x 1 apache apache 12321980 Feb 29 2012 bangnew
-rwxr-xr-x 1 apache apache 11824732 Jan 23 2011 bangold
-rw-r–r– 1 apache apache 44 Aug 3 03:28 cron.d
-rwx–x–x 1 apache apache 14679 Nov 2 2005 f4
-rwxr-xr-x 1 apache apache 15988 Sep 7 2002 juno
-rw-r–r– 1 apache apache 11 Aug 3 03:28 mech.dir
-rwx–x–x 1 apache apache 566 Jan 20 2013 mech.set
-rwxr-xr-x 1 apache apache 27 Jan 11 2011 run
-rwx–x–x 1 apache apache 152108 Jan 11 2011 sshd:
-rwxr-xr-x 1 apache apache 17 Nov 5 2008 start
-rwxr-xr-x 1 apache apache 8231 Feb 29 2012 std
-rwxr-xr-x 1 apache apache 13399 Aug 6 2000 stealth
-rwx–x–x 1 apache apache 8790 Jan 23 2006 stream
-rwxr-xr-x 1 apache apache 17690 Feb 6 1996 synk
-rwxr-xr-x 1 apache apache 6442 Jun 23 2011 talk
-rwxr–r– 1 apache apache 166 Aug 3 03:28 update
-rwx–x–x 1 apache apache 14841 Jul 22 2005 v
-rwxr-xr-x 1 apache apache 14911 Mar 6 2002 v2
End Result
End result: This server ahs been root compromised. The only solution is to reinstall and slave drive the existing compromised drive.
Verisign SSL Certificates
You have generated a certificate request (CSR and private key) using plesk. You would like to know how to complete the certificate request process. The Verisign digital certificate can be downloaded in the X.509 format as three files. The three files are designated as:
1) End Entity Certificate
2) First Intermediate Certificate
3) Second Intermediate Certificate
When the Plesk CSR function is submitted, it prompts for only two values:
1) Certificate
2) CA certificate
How are these values determined since there are 3 files returned, but Plesk prompts for 2 values?
1) indicate which Verisign file is mapped to the Certificate field.
2) indicate which Verisign file is mapped to the CA certificate field.
Answer:
The End Entity Certificate is your SSL created to match your public key. The contents of the entity certificate should be placed into the Certificate field of Plesk.
The contents of both the First Intermediate and Second Intermediate will need to be placed into Plesk’s CA Certificate field. These should be pasted in order to create a two part chain certificate.
You should be able to open all of these in the notepad or wordpad programs to view the plain text contents of each certifcate. This will facilitate copy/pasting of the content into Plesk for all certificate fields.
Migrate MySQL from Slaved Drive
1. Mount the slave drive. We’ll assume you mounted it at /media/slave
Find the drive:
# fdisk -l Disk /dev/sda: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x000374d4 Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 587 4194304 82 Linux swap / Solaris Partition 2 does not end on cylinder boundary. /dev/sda3 587 121602 972054528 83 Linux Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes 255 heads, 63 sectors/track, 121601 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdb1 * 1 62 497983+ 83 Linux /dev/sdb2 64 584 4184932+ 82 Linux swap / Solaris /dev/sdb3 585 121598 972044955 82 Linux swap / Solaris
sdb is the drive – the slaved drive after the reinstall
Check to see if it is ext3 or ext4
# blkid /dev/sdb3 /dev/sdb3: UUID="52721885-a9af-45e9-89f5-5f26ffca55dd" TYPE="ext3"
Mount according to ext3 or ext4
mount -t ext3 /dev/sdb3 /media/slave
Add to fstab
# nano /etc/fstab /dev/sdb3 /media/slave ext3 default 0 1
2. Edit the MySQL config file to point to the slave’s mysql databases
nano /etc/my.cnf
# datadir = /var/lib/mysql datadir = /media/slave/var/lib/mysql
service mysqld restart
3. Export the required database
mysqldump -u root -p[root_password] [database_name] > dumpfilename.sql
for plesk:
mysqldump -u admin -p`cat /etc/psa/.psa.shadow` [database_name] > dumpfilename.sql
4. Reset the Mysql path and import the file
nano /etc/my.cnf
datadir = /var/lib/mysql # datadir = /media/slave/var/lib/mysql
service mysqld restart
mysql -u root -p[root_password] [database_name] < dumpfilename.sql [/bash] Plesk: [bash] mysql -u admin -p`cat /etc/psa/.psa.shadow` [database_name] < dumpfilename.sql [/bash] Hotkey for Plesk specifically mounted to /olddrive/: Before migrating, make sure the database you are migrating has already been created in Plesk with the correct username and password. 1. Log onto your server as root using ssh. 2. Edit the mysql config file to use the slave drive nano /etc/my.cnf 3. Comment out the current path, add your slaved drive’s path and save the file [bash] # datadir = /var/lib/mysql datadir = /olddrive/var/lib/mysql [/bash] (save the file using <ctrl><o> then <ctrl><x> to exit. 4. Restart mysql to load the new settings [bash] service mysqld restart
5. Create a dump file of the desired database
mysqldump -u admin -p`cat /etc/psa/.psa.shadow` [database_name] > /tmp/database_name.sql
(Repeat this step for all databases that need to be imported)
6. Repeat step 2-4 and reset the original setting
datadir = /var/lib/mysql # datadir = /olddrive/var/lib/mysql
7. Import the database
mysql -u admin -p`cat /etc/psa/.psa.shadow` [database_name] < /tmp/database_name.sql [/bash] (Repeat this step for all .sql files created in step 5)