Vyacheslav Gapon – personal blog, manuals, articles, notes, development
Suppose you installed FreeRADIUS 2 as written in this article – Installation and configuration of the ABillS billing system
Now copy the dhcp.conf file into the FreeRADIUS configuration:
sudo cp /usr/abills/misc/freeradius/v2/dhcp.conf /usr/local/freeradius/etc/raddb/sites-enabled/
I noticed one time when I received a call from the Asterisk console:
dial_exec_full: Unable to create channel of type ‘SIP’ (cause 20 – Subscriber absent)
In the context of the dialplan, I make a call simultaneously to two phones:
exten => s,5,DIAL(SIP/204&SIP/203,19)
Sometimes one of the IP phones is turned off, which is why this error occurs, informing that there is no subscriber.
To solve it, you just need to turn on the IP phone.
You can see information about SIP in the Asterisk console:
asterisk -rvv sip show peers sip show peer NUMBER quit
If the client’s IP address is null and expire is -1, the SIP client is not online:
Expire: -1 Addr->IP: (null)
Switch directly to the root user:
sudo -i
Let’s see the list of disks:
fdisk -l df -h
You can see the information and model of the disk as follows:
hdparm -i /dev/sda
If SMART is supported, install the utilities and see the SMART statistics:
apt-get install smartmontools smartctl -a /dev/sda smartctl -a /dev/sda|grep -i reallocated
Run SMART tests and view information (smartctl -X to stop the long test):
smartctl -H /dev/sda smartctl --test=long /dev/sda smartctl -l selftest /dev/sda
Now we will perform a disk check on the broken sectors (-s will display information about scanning, -v more detailed mode):
badblocks -sv /dev/sda1
You can save the result to a file:
badblocks -sv /dev/sda1 > ~/badblocks.list
You may need to unmount the disk to check:
umount /dev/sda1
You can run the test using e2fsck like this:
e2fsck /dev/sda1
See also:
Description of SMART attributes
Diagnostics HDD using smartmontools
iotop – a console program that displays statistics on the use of disk space.
You can install Debian, Ubuntu, Mint with the command:
sudo apt-get install iotop
In Red Hat, Fedora, CentOS:
yum install iotop
Normal startup:
iotop
Running with the option:
iotop OPTION
I’ll describe the possible startup options:
–version (view version)
-h (view help)
-o (display only active processes or threads that read or write, instead of displaying all)
-b (inclusion of non-interactive mode, convenient for example to output information to a file)
-t (display time in each line, for non-interactive mode -b)
-n NUMBER (the number of iterations after which the output will be executed, if not specified, then the output is not standardized)
-d NUMBER (the delay between iterations in seconds, you can specify not an integer, a standard value of 1)
-p PID (display statistics only for the specified processes / threads, standard for all)
-u USER (display statistics only for specified users, standard for all)
-P (display only processes)
-a (accumulation of statistics from the start of the launch of iotop)
-k (statistics in kilobytes)
-q (shortened view, some header lines are removed, when used with the -b option. There are more abbreviated, for example -qq without title names and -qqq without a general summary)
grep – A utility for searching for specified text in files, file names, etc. from the command line.
Continue reading “Searching for text using grep”cPanel allows you to use several web interfaces at once for viewing mail, sometimes they can be disabled or perhaps some of them need to be disabled.
Continue reading “How to enable Horde, SquirrelMail and RoundCube in cPanel”The acct utility allows you to see statistics of user activity in the system.
Installation in Ubuntu:
sudo apt-get install acct
Removed in Ubuntu with the following command:
sudo apt-get remove acct
Installation in Fedora:
su -c 'yum install psacct'
Running in Ubuntu:
/etc/init.d/acct start
Running in Fedora:
su -c 'service acct start'
I will list and describe several commands of the acct utility:
ac – statistics on the time spent by users in the system
ac -d (per day)
ac -y (in a year)
ac -p (individual statistics)
ac –version (display version of the utility)
man ac (help on the team)
sa – information about executed commands and running applications
sa -c (statistics in percent)
man sa (help on the command)
lastcomm – last executed commands
sudo accton on/off – on and off collection of information
It took one day to disable the ecryptfs encryption of the home directory, which was once set up when installing the system.
First of all, we make a copy of the home directory of the right user:
sudo cp -rp /home/user /home/user_backup
Get the mount point in the directory:
PRIVATE=`cat ~/.ecryptfs/Private.mnt 2>/dev/null || echo $HOME/Private`
Unmount the directory:
ecryptfs-umount-private
Install the rights to the directory:
chmod 750 $PRIVATE
Delete the directory and directories ~/.Private, ~/.ecryptfs:
rm -rf $PRIVATE ~/.Private ~/.ecryptfs
And also in the made copy:
rm -rf /home/user_backup/.Private /home/user_backup/.ecryptfs
If ecryptfs is no longer used in the system, then we will delete the utilities:
sudo apt-get remove ecryptfs-utils libecryptfs0
Install the right user directory:
sudo chmod 750 /home/user sudo chown user:user -R /home/user
Copy the necessary files from the backup copy of the home directory.
Done.
You can see the built-in statement with the command:
ecryptfs-setup-private --undo
See also:
The solution to the error “Could not chdir to home directory /home/user: Permission denied”
Moved once the system to another disk and when connected via SSH saw the following errors:
Continue reading “The solution to the error “Could not chdir to home directory /home/user: Permission denied””nice – allows you to specify the priority of the processor performing various tasks, the range of priorities is -20 to 19, where 19 is the smallest, if not specified, then there will be a standard priority of 0. Convenient for example when packing data into archives so that this task does not load the server or when many processes need to be started, distributing the load, which occupy all CPU time.
Example of the execution of the command with the lowest priority:
nice -n 19 COMMAND
See the table of processes and their priorities as follows (column NI):
ps axl ps -l
If the table is large, you can redirect the output of the command to Less and look at the page:
ps axl | less
To change the priority:
renice -n 19 PROCESS(PID)
Checking the default priority value (standard 0):
nice
ionice – allows you to specify the priority for I/O operations, for example, to reduce the load on the disk. The first class is from 1 to 3, then the priority is from 0 to 7, where 7 is the smallest.
There are three classes:
1) Real time – Preemptive without paying attention to other processes, indicating priorities from 0 to 7.
2) Best Effort — Standard with priorities from 0 to 7.
3) Idle — With idle time without priority.
Example of executing the command with the lowest I/O priority:
ionice -c2 -n7 COMMAND
To change the priority:
ionice -c2 -n7 -p PROCESS(PID)
To view the set priority:
ionice -p PROCESS(PID)
You can specify priorities at the same time via nice and ionice:
nice -n 19 ionice -c2 -n7 COMMAND
To specify high priorities, for example, you might need root permissions, this command should be executed as root user or added before the sudo command.