Category Archives: Linux

Install Hashcat on Fedora

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Install nVidia drivers.  Guide here.

Download binary files from the hashcat website

https://hashcat.net/hashcat/

or use wget

wget https://hashcat.net/files/hashcat-4.1.0.7z

Extract with p7zip

7z x hashcat-4.1.0.7z

cd into the hashcat directory

cd hashcat-4.1.0

Run hashcat

./hashcat64.bin -t 32 -a 7 example0.hash ?a?a?a?a example.dict

Example script:

sudo dnf install p7zip
wget https://hashcat.net/files/hashcat-4.1.0.7z
7z x hashcat-4.1.0.7z
cd hashcat-4.1.0
./hashcat64.bin -t 32 -a 7 example0.hash ?a?a?a?a example.dict

Errors:
If you get the following error, try re-extracting the 7z file with the “x” option, not “e”.  “x : eXtract files with full paths” and ” e : Extract files from archive (without using directory names)”

inc_cipher_aes256.cl: No such file or directory

Install nVidia GeForce Drivers on Fedora 27

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Install free and non-free rpmfusion

sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm

Install drivers

dnf install xorg-x11-drv-nvidia akmod-nvidia
dnf install xorg-x11-drv-nvidia-cuda 
dnf update -y

Reboot

reboot

You may need to set the DPI settings.  See here for more details.

Increase Disk Size of Linux VM in VMware

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This is for extending a regular Ubuntu Linux partition, if you need to resize, expand a LVM partition refer to this guide.  I am using Gparted as I ran into some issues using parted for moving the partitions around.

Shut the VM down,

sudo shutdown -h now

It is a good idea to take a snapshot of the VM before resizing the disk, so if you run into an issue you have something to revert back to.  In the vSphere Client, right click on the VM -> Snapshot -> Take Snapshot.

Change VM Disk size by right clicking on the VM and going to Edit Settings

You can now boot up the VM.  Fire up GParted and it should show some unallocated space at the end of your drive.

Now in the next two images we are moving the Extended partition, which contains the Swap Partition to the end of the drive, so the unallocated space is adjacent to our root partition.

  1. Turn off the swap space by right clicking on the swap partition and hit Swapoff.
  2. Right click on the extended partition and extend to the the end of the Drive
  3. Right click on linux-swap and move to the end of drive.
  4. You should now have something similar to this

Hit Apply and write the changes to the disk then

  1. Right click on the extended partition and shrink to the end
  2. Right click on /dev/sda1 “Root partition” and extend to extended partition.

It should now look like this

Hit apply, then right click on the linux-swap and turn Swapon.

Enjoy the extra space.

Parted resizing notes

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Launch parted with the following command.  Specify the disk you want to modify.  In this case /dev/sda.

sudo parted /dev/sda

Print partition and available free space.  If you just run print, it will not show you the available free space.

(parted) print free

You can resize, or rather extend a partition using the “resizepart” command inside parted.  Command syntax is as follows

(parted) resizepart PartitionNumber End

Example: Resize partition 1 to 30GB.  Note you’ll need to specify the end part with the GB, otherwise, you’ll be shrinking the partition or making a mess…  You can see what space is available with the “print free” command above

(parted) resizepart 1 30GB

After you have run the resizepart in parted, you’ll need to grow the filesystem, so run one of the following commands from the local shell.

resize2fs /dev/sda1

Or for XFS partitions

xfs_growfs /dev/sda1

You can check the partition size with

df -h

or

sudo fdisk -l /dev/sda

Setup Secure FTP server on CentOS

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Setup SFTP Server

When finished you’ll have a SFTP server setup that is configured so the users are in a chroot environment, and can not ssh, or telnet to the server.

Install SSH server if it is not already

yum install openssh-server openssh-client

Create group that is limited to sftp so they can’t ssh, scp etc.

groupadd sftpusers

Add chroot settings to /etc/ssh/sshd_config.  The %u is a variable, which is the users username.

Match Group sftpusers
ChrootDirectory /sftp/%u
ForceCommand internal-sftp

Make ftp directory

mkdir /sftp

Add SFTP user

useradd -g sftpusers -d /sftp -s /sbin/nologin newsftpuser

Create password for new user

passwd newsftpuser

Create directory for user

mkdir /sftp/newsftpuser

Create directory to put ftp files

mkdir /sftp/newsftpuser/files

Change permissions

chown newsftpuser:sftpusers /sftp/newsftpuser/files/

Restart sshd

systemctl restart sshd

Should be good to go.  Test it by logging in with your favorite FTP client.

Add Self Signed SSL certificate to LibreNMS in CentOS

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Install mod_ssl

yum install mod_ssl -y

Create Directory for SSL key.

mkdir /etc/ssl/key
chmod 700 /etc/ssl/key

Create certificate.

openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/pki/tls/private/localhost.key -out /etc/pki/tls/certs/localhost.crt

Fill out the info or what is applicable.

Now edit the LibreNMS Apache config file /etc/httpd/conf.d/librenms.conf

All you have to do is add the following three lines under the VirtualHost and change *:80 to *:443.

SSLEngine on
SSLCertificateFile /etc/pki/tls/certs/localhost.crt
SSL CertificateKeyFile /etc/pki/tls/private/localhost.key

So when your finished the file should look like this.

<VirtualHost *:443>
 DocumentRoot /opt/librenms/html/
 ServerName server_hostname_or_IP
 SSLEngine on
 SSLCertificateFile /etc/pki/tls/certs/localhost.crt
 SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
 CustomLog /opt/librenms/logs/access_log combined
 ErrorLog /opt/librenms/logs/error_log
 AllowEncodedSlashes NoDecode
 <Directory "/opt/librenms/html/">
 Require all granted
 AllowOverride All
 Options FollowSymLinks MultiViews
 </Directory>
</VirtualHost>

Don’t forget to allow https/port 443 traffic through the firewall.  Guide here

If you have any issues, you may need to chmod the key and crt file.

chmod 644 /etc/pki/tls/certs/localhost.crt
chmod 644 /etc/pki/tls/private/localhost.key

You should now be able to access LibreNMS using https.  Note, you’ll need to allow an exception in your browser for your self signed certificate.

https://LibreNMS_IP_Address

Recovering LibreNMS from crashed XenServer VM

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Had a LibreNMS instance crash, or the VM crashed, not bootable anymore.  Was able to boot it up on a CentOS iso with rescue mode, which gave me access to the files.  So the idea is to manually copy off the LibreNMS files and LibreNMS database and import them to a new LibreNMS instance

Issues

  • Need to access the the system files
  • MySQL doesn’t start in a chroot environment, so no way to do a mysqldump —  (Has to do with systemv or something)

Steps

  1. Create new LibreNMS VM with a new instance of LibreNMS installed
  2. Gain access to the crashed system
  3. Copy over LibreNMS MySQL databases to new LibreNMS instance
  4. Copy over LibreNMS files “/opt/librenms” to new LibreNMS instance
  5. Clean up.  Set users on directories, check SELinux etc.

1. Installing New LibreNMS VM

  • Guide for Ubuntu/Debian distro’s here
  • Guide for for Fedora/CentOS/RedHat here

2. Gaining access to crashed VM

There can be a couple of ways to gain access to a crashed XenServer VM.  One of the easiest ways is to boot up in recovery mode and go through the installers rescue mode.  Guide to boot up XenServer VM in recovery mode here.

The installer rescue mode should detect the OS and mount everything.  If not you should be able to mount the root partition manually.

Once booted up, you’ll need to enable network access if your going to use sftp or scp to copy files.  There are a few different ways to do this

  • Run “dhclient” to pull an address via DHCP
  • Set a static IP address
    • Guide for Ubuntu/Debian distro’s here
    • Guide for fedora/CentOS/RedHat here

3.Copy LibreNMS Mysql Database

Backup the LibreNMS MySQL database directory

tar czvf librenms_mysql.tgz /var/lib/mysql

Use scp or sftp to copy it to the new LibreNMS instance

scp librenms_mysql.tgz user@new_LibreNMS_ip

Now on the new LibreNMS instance we need to run the following few commands

systemctl stop mariadb
rm -rf /var/lib/mysql/*
tar xzvf librenms_mysql.tgz -C /
chown -R mysql:mysql /var/lib/mysql

4. Copy LibreNMS directory

Backup the LibreNMS directory

tar czvf librenms.tgz /opt/librenms

Use scp or sftp to copy it to the new LibreNMS instance

scp librenms.tgz user@new_LibreNMS_ip

Now on the new LibreNMS instance we need to run the following few commands

rm -rf /opt/librenms/*
tar xzvf librenms.tgz -C /
chown -R librenms:librenms /opt/librenms

5. Clean up

Disable SELinux if you have not already.  Guide here

Restart apache, and start mysql.  If your on Ubuntu, the services are named apache2 and mysql

systemctl restart httpd
systemctl restart mariadb

That should get it working, if not try a reboot.

Special notes

The whole MySQL directory needs to be copied, there are innodb files that will keep MySQL from starting if they are not copied.

There is some good info here
https://stackoverflow.com/questions/1795176/how-to-change-mysql-data-directory

SSH Errors

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ssh: connect to host 192.168.1.158 port 22: Connection refused

Wrong SSH port.  Check /etc/ssh/sshd_config on linux, or in RouterOS IP->services->SSH

ssh_exchange_identification: Connection closed by remote host

Check the hosts.allow and hosts.deny files. If your getting this error connecting to a Mikrotik check the IP services and the “Available From” addresses.

How to chroot into a Linux drive

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Chrooting can be super useful for changing things like the root password, repairing grub bootloader etc., things that require the system to be mounted.  Typically if your chrooting into an OS drive you can boot up on a Live Linux distro, or use the Rescue feature on some Linux installers.

Mount main drive

Change sdb2 to the root partition of your drive.

mount /dev/sdb2 /mnt

Mount other stuff

mount -t proc none /mnt/proc
mount -o bind /dev /mnt/dev
mount -o bind /sys /mnt/sys
mount -o bind /run /mnt/run

If you want to, you can mount the boot partition.  Change sdb1 if your boot partition is something else.  For efi, you may need to mount the boot partition then mount the efi partition inside /boot/efi.

mount /dev/sdb1 /mnt/boot

Chroot

 chroot /mnt

You should now be inside the chroot environment.  To exit the chroot, hit control+d or type exit.

If your having issues resolving DNS refer to this post.

Install LibreNMS on CentOS

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Install prerequisites

yum install -y epel-release 
rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm
yum install -y policycoreutils-python cronie fping git httpd ImageMagick jwhois mariadb mariadb-server mtr MySQL-python net-snmp net-snmp-utils nmap php71w php71w-cli php71w-common php71w-curl php71w-gd php71w-mcrypt php71w-mysql php71w-process php71w-snmp php71w-xml php71w-zip python-memcached rrdtool

Setup LibreNMS user

useradd librenms -d /opt/librenms -M -r
usermod -a -G librenms apache

Install LibreNMS

cd /opt
git clone https://github.com/librenms/librenms.git librenms

Configure MySQL

Start MySQL

systemctl start mariadb
mysql -u root

Create the Database and database user. Change password to a different password

CREATE DATABASE librenms CHARACTER SET utf8 COLLATE utf8_unicode_ci;
CREATE USER 'librenms'@'localhost' IDENTIFIED BY 'password';
GRANT ALL PRIVILEGES ON librenms.* TO 'librenms'@'localhost';
FLUSH PRIVILEGES;
exit

Disable MySQL strict mode

vi /etc/my.cnf

Add the following in the [mysqld] section

innodb_file_per_table=1
sql-mode=""
lower_case_table_names=0

Enable and restart mariadb i.e.(MySQL)

systemctl enable mariadb
systemctl restart mariadb

Configure PHP.  Set Timezone

You can go here to figure out which time zone you need.

vi  /etc/php.ini

Find the [Date] Section and change the timezone

Example:

date.timezone = America/New_York

Configure Apache

vi /etc/httpd/conf.d/librenms.conf

Add the following, change the server name.

<VirtualHost *:80>
  DocumentRoot /opt/librenms/html/
  ServerName  librenms.example.com

  AllowEncodedSlashes NoDecode
  <Directory "/opt/librenms/html/">
    Require all granted
    AllowOverride All
    Options FollowSymLinks MultiViews
  </Directory>
</VirtualHost>

Enable and restart apache

systemctl enable httpd
systemctl restart httpd

Allow fping

cd /opt/librenms
vi http_fping.tt

Add the following

module http_fping 1.0;

require {
type httpd_t;
class capability net_raw;
class rawip_socket { getopt create setopt write read };
}

#============= httpd_t ==============
allow httpd_t self:capability net_raw;
allow httpd_t self:rawip_socket { getopt create setopt write read };

Configure SELinux

You can disable SELinux completely in the /etc/selinux/config file or run these commands to make LibreNMS and SELinux play together.

semanage fcontext -a -t httpd_sys_content_t '/opt/librenms/logs(/.*)?'
semanage fcontext -a -t httpd_sys_rw_content_t '/opt/librenms/logs(/.*)?'
restorecon -RFvv /opt/librenms/logs/
semanage fcontext -a -t httpd_sys_content_t '/opt/librenms/rrd(/.*)?'
semanage fcontext -a -t httpd_sys_rw_content_t '/opt/librenms/rrd(/.*)?'
restorecon -RFvv /opt/librenms/rrd/
setsebool -P httpd_can_sendmail=1
checkmodule -M -m -o http_fping.mod http_fping.tt
semodule_package -o http_fping.pp -m http_fping.mod
semodule -i http_fping.pp

Configure Firewall

firewall-cmd --zone public --add-service http
firewall-cmd --permanent --zone public --add-service http
firewall-cmd --zone public --add-service https
firewall-cmd --permanent --zone public --add-service https

Configure snmpd

cp /opt/librenms/snmpd.conf.example /etc/snmp/snmpd.conf

Edit the snmpd file and change RANDOMSTRINGGOESHERE to your community string

vi /etc/snmp/snmpd.conf

Enable and restart snmpd

curl -o /usr/bin/distro https://raw.githubusercontent.com/librenms/librenms-agent/master/snmp/distro
chmod +x /usr/bin/distro
systemctl enable snmpd
systemctl restart snmpd

Setup Cron Job and Cycle logs

cp /opt/librenms/librenms.nonroot.cron /etc/cron.d/librenms
cp /opt/librenms/misc/librenms.logrotate /etc/logrotate.d/librenms

Set Permisions

chown -R librenms:librenms /opt/librenms
setfacl -d -m g::rwx /opt/librenms/rrd /opt/librenms/logs
setfacl -R -m g::rwx /opt/librenms/rrd /opt/librenms/logs

Finish Install

Finish the install by

http://your-server-ip/install.php