Important commands for Linux OS Patching & NFS Server Administration

Important commands for Linux administration 

                        - Firewall/OS Patch/NFS Server configuration

OS Patching Related Commands: -

To clean up cached data -

#yum clean all  

To download yum repository data to cache

#yum makecache

To refresh data from available repositories

#yum repolist

To check latest packages update which we can update

#yum check-update

To update all packages including kernel -

#yum update

If we want to exclude some packages from update like java & httpd

#yum update --exclude java,httpd

To check package information -

#yum info pkgname 

To download any package 

#yumdownloader pkgname

To remove any package

#yum remove pkgname

To view the history of yum transactions -

#yum history

To roll back last yum transaction -

#yum history undo transaction ID 

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1. To register linux server with your account: -

#subscription-manager register --username amiteshjsk --password *******  --auto-attach

2. To mount your .iso file in linux server: -

#mount -o loop rhel-server-7.3-x86_64-dvd.iso /mnt/iso

3.To set Proxy address in Linux server: -

#export http_proxy=http://192.168.11.40:8080/

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4.To configure NFS in Linux server: -

first of all, you have to make entry in /etc/exports of nfs server like:-

/mnt/iso (rw,sync,no_root_squash)

Note: - /mnt/iso (desired mount which you want to share)

 If you want to share mount point with onle selected host then make entry in /etc/exports like: -

/mnt/iso 192.168.11.42 (rw,sync,no_root_squash)

After that restart nfs service: -

#service nfs restart

Now you can check shared mountpoint details by below command: -
#showmount -e
Export list for MONITORING:
/mnt/iso *

NFS using ports 2049 TCP and 111 UDP and we need to check reachability using telnet host and port

Note- If firewall service is running then we need to add permanent ports in Firewall

#firewall-cmd --permanent --add-port=111/udp

#firewall-cmd --permanent --add-port=2049/tcp

Reload firewall service

#systemctl reload firewalld

To check firewall added port list

#firewall-cmd --list-ports

now mount in client server after creating a directory

#mkdir iso
#mount -t nfs 192.168.11.41:/mnt/iso /iso

Note: - 192.168.11.41 (NFS Server IP )