1. Login as the user that you want to setup the ssh keys, in this case we are using user test1. 2. Create a private and public key: [test1@server4 ~]$ ssh-keygen Generating public/private rsa key pair. Enter file in which to save the key (/home/test1/.ssh/id_rsa): Created directory ‘/home/test1/.ssh’. Enter passphrase (empty for no passphrase): Enter […]
Linux
How to Convert PuTTY’s private key (.ppk) to SSH key
1. Launch PuTTY Key Generator (puttygen.exe) 2. Click on the File → Load private key and select your PuTTY’s key file, which normally ends with .ppk extension. 3. Enter the key’s passphrase if prompted. 4. Detail of the imported key will be displayed. 5. Go to Conversions → Export OpenSSH key from the menu. 6. […]
How To Configure Timeout On SSH Client Putty
Question: How to configure timeout on PUTTY to keep alive the ssh session? The SSH Connection has timeout due to inactivity at the TCP communications level where the server will decide to disconnect if it sees no activity on the connection for a certain amount of time. In order to configure timeout in Putty, check […]
Couldn’t find device with uuid [UUID] – LVM Not Active on Reboot
The Problem After a reboot the system will not start or activate one of the LVM volume groups. Trying to activate the group manually produces the message: Couldn’t find device with uuid ‘[UUID]’ The Solution The string LABELONE at the metadata location marks the device as being part of an LVM device. Without this string, […]
How To Check Current Values for Kernel Tuning Parameters in CentOS/RHEL
Question: How to check to current values for these kernel parameters? net.core.netdev_max_backlog fs.file-max net.ipv4.tcp_max_syn_backlog net.core.somaxconn The linux system could not support to method for directly check these values but we can check to using by below commands : # netstat -an | grep -c SYN_RECV # netstat -s Also, those parameter can be checked from […]
How to calculate recommended value of vm.min_free_kbytes Kernel Tuning Parameter
/proc/sys/vm/min_free_kbytes: This controls the amount of memory that is kept free for use by special reserves including “atomic” allocations (those which cannot wait for reclaim). Setting vm.min_free_kbytes too low prevents the system from reclaiming memory. This can result in system hangs and OOM-killing multiple processes. However, setting this parameter to a value that is too […]
how to rotate Tang Server Keys and update the Clevis Client
This post explains how to rotate Tang Server Keys and update the Clevis Client. Note, below is an example hence all certificates, keys and device names/uuid’s are fictional. Change the keys on the tang server 1. Check existing key: # ls -la /var/db/tang total 8 dr-xrws—. 2 tang tang 84 Jun 26 11:24 . drwxr-xr-x. […]
Disk Encryption Using Network Based Key Services (NBDE) on CentOS/RHEL 8
Question: How to create an encrypted XFS filesystem that’s automatically unlocked at boot using clevis (client) and tang (server)? Red Hat has included disk encryption for years with Linux Unified Key Setup-on-disk-format (LUKS). This solution is easy to implement and configure for your encryption needs, but the management and practicality of its key management is […]
“Volume “myvg/vol01″ Is Not Active Locally” – CentOS/RHEL
The Problem While trying to create a logical volume, lvcreate fails with error “Volume “myvg/vol01″ Is Not Active Locally” even though the volume group is active, with an error output such as the following: [root@ ~]# lvcreate -L 4G myvg Volume “myvg/vol01” is not active locally. Aborting. Failed to wipe start of new LV. The […]
“Authorization not available. Check if polkit service is running or see debug message for more information” – CentOS/RHEL 7 ssh service error
The Problem Starting ssh services errors out and spool messages regarding polkit service. # service sshd restart Redirecting to /bin/systemctl restart sshd.service Authorization not available. Check if polkit service is running or see debug message for more information. Same issue is encountered when starting the polkit service. # service polkit restart Redirecting to /bin/systemctl restart […]