You get following error output by ntpd and docker in CentOS 7 Dec 2 16:12:11 server1 ntpd[xxxx]: ./../lib/isc/unix/interfaceiter.c:248: unexpected error: Dec 2 16:12:11 server1 ntpd[xxxx]: br-22eee3e444b: getting interface flags: No such device The above error message is harmless if ntpd is not listening on this interface. The best solution is to use chronyd, which is …
What is SSH and its Authentication Methods: Usage and Troubleshooting
Overview: The Secure shell, also called the SSH protocol, is used to make reliable and secure communication between two servers connected to a local or public network. The SSH protocol supports various authentication methods and uses strong encryption to protect exchanged data on the network. It is highly recommended to use SSH-based communication instead of …
XFS filesystem not checked during boot
XFS stores the actions that were to be taken at the time server unexpectedly shut down in a journal. Therefore, XFS does not have any filesystem corruption. You may check the XFS filesystem with mount and unmount commands like mount /dev/sda and umount /dev/sda.
Repair Linux filesystem in rescue mode
Attach CentOS ISO image with virtual media of server and boot from virtual cdrom. When the boot screen appears type Linux rescue or selects the Linux rescue option if available. Select rescue installed system. Select relevant option when language and keyboard selection appears on the screen. Select no for enabling network devices like eth0 or …
Find if pNFS is enabled on NFS client
On the NFS client, execute the following command and in output check, if pnfs=not configured is present. egrep "nfs(v)?4" /proc/self/mountstats device NFS-Server-IP:/mnt/path-shared mounted on /mnt/point with fstype nfs4 statvers=1.2 nfsv4: bm0=0xfdfbbbff,bm1=0x40f9bui3e,bm2=0x906,acl=0x3,sessions,pnfs=not configured
Disable or Enable Journaling On ext4 Filesystem
You can only use the ordered journaling method on a Linux Server. First check if the journal feature is enabled on ext3/ext4 filesystem with the following command: tune2fs -l /disk-path Check the output of the above command for has_journal which indicates the journaling is enabled on the filesystem. Filesystem features: has_journal ext_attr resize_inode dir_index filetype …
Disable HTTP OPTIONS method on Linux Apache server
You can use RewriteCond and RewriteRule on a webserver. The RewriteRule evaluates the HTTP method used and RewriteRule blocks the request with error 403 Forbidden. RewriteCond %{REQUEST_METHOD} ^(PUT|DELETE|TRACE|OPTIONS|CONNECT)$ [NC] RewriteRule .* - [F]
Backup old files before overwriting in rsync
By default, rsync overrides old files in the destination server/folder. To resolve this use the –backup flag in rsync. rsync -a –backup –backup-dir=”/src-old-files” /usr/src/ root@85.17.219.154:/src-backup/ The above rsync command will copy files from local server /usr/src to root@85.17.219.154:/src-backup/. If some files are overwritten in root@85.17.219.154:/src-backup/, these will be backed up in root@85.17.219.154:/src-old-files first before they …
How to check progress of the rsync job
You can add the progress option with rsync command: rsync -a --progress /media/backup-folder/ sending incremental file list created directory backup or you can add the -P flag in rsync command as below: rsync -a -P /media/backup-folder/ sending incremental file list created directory backup Note that the -P option includes both –partial and –progress rsync options.
Exclude more than one directory with rsync
To exclude a single directory with rsync use the following command rsync -av -e --exclude='/directory-path/' ip:/destination-folder rsync -av -e --exclude='/directory-path-1' --exclude='/directory-path-2/*' ip:/destination-folder