How to Lock user account in Linux/ how to Unlock user account in Linux

Locking and Unlocking user in linux

In this post we will learn about how to lock and unlock user account in linux. With the help of two commands you can lock and unlock the user account in linux. We will also know, how to find the user account has lock and unlock status.

After creating a user to modify the attributes of user like changing Uid, changing Secondary group id or adding a comment or sometimes it’s required to lock user account so that he can not login to the machine. This is done for security reasons so that unauthorized users are not allowed to login. Locking user account can be done by following two commands.

To Lock the user account in Linux,use the given below command

We have two options to use any of the given below command to lock the user account in linux

By Using Passwd command

Syntax :                #passwd –l <username>

#passwd -l username

[root@linuxelearn ~]# passwd -l rahul Locking password for user rahul. passwd: Success [root@linuxelearn ~]# [root@linuxelearn ~]# tail /etc/shadow rpcuser:!!:17026:::::: nfsnobody:!!:17026:::::: pulse:!!:17026:::::: gdm:!!:17026:::::: sshd:!!:17026:::::: tcpdump:!!:17026:::::: user:$6$kYw9IHnXahbyylyd$.fMwQf.WnzN7ftRawlOYPHAXsYZ3JvfOjawESWYBA8sWv413yfqqfWcdGXOcPoN6PFyXUmrh452c4XS2chJj30:17026:0:99999:7::: rahul:!!$6$IfqyPCtQ$v5275VCBDdM5iecTfWBVvs4gOClXyEiauVHS7Aa9861cpwo3GKAQnyYuNdK4O85Pr9QS8HW5fJvTUn9pCGWhg1:17027:0:99999:7::: nagios:$6$9YMaBpCe$U4puQbI98S.epxe21aiwOnpTBLEYl/jfAXfdkUzIEw75Cw/WIvGAt254QiBEBf3lZ6niwAJJwAFyf6u/XAEso1:17037:2:7:1:0:17040: pooja:$6$SM3See4e$Yk1lSTk8G09zvrIYZv0W13hIolfQSQyyyTt5RT35nNqVpDft3hmegQN9p9.nd1rig/9VgolhNNlNgsk.Bz3Q5/:17153:0:99999:7::: [root@linuxelearn ~]#

In above example after locking the user account by using passwd command. The double exclamation(!!) sign after username called rahul confirmed the account is locked.

OR

By using usermod command

Syntax :                # usermod <options> <username>

Options are:

All the options which are used with useradd command can be used and also the following,

• -l             To change login name
• -L            To LOCK account
• -U           To UNLOCK account

• Ex           #usermod  -l   newname oldname
• Ex           #usermod –L username
• Ex           #usermod –U username

Note: - When an account is locked it will show ! (Exclamation mark) in /etc/shadow file.

Locking a user account:

To lock a user account use the following

#usermod –l  rahul

And verify it in /etc/shadow file, it shows exclamation mark before user account or try login as rahul

[root@linuxelearn ~]# usermod -L rahul [root@linuxelearn ~]# tail /etc/shadow rpcuser:!!:17026:::::: nfsnobody:!!:17026:::::: pulse:!!:17026:::::: gdm:!!:17026:::::: sshd:!!:17026:::::: tcpdump:!!:17026:::::: user:$6$kYw9IHnXahbyylyd$.fMwQf.WnzN7ftRawlOYPHAXsYZ3JvfOjawESWYBA8sWv413yfqqfWcdGXOcPoN6PFyXUmrh452c4XS2chJj30:17026:0:99999:7::: rahul:!$6$IfqyPCtQ$v5275VCBDdM5iecTfWBVvs4gOClXyEiauVHS7Aa9861cpwo3GKAQnyYuNdK4O85Pr9QS8HW5fJvTUn9pCGWhg1:17027:0:99999:7::: nagios:$6$9YMaBpCe$U4puQbI98S.epxe21aiwOnpTBLEYl/jfAXfdkUzIEw75Cw/WIvGAt254QiBEBf3lZ6niwAJJwAFyf6u/XAEso1:17037:2:7:1:0:17040: pooja:$6$SM3See4e$Yk1lSTk8G09zvrIYZv0W13hIolfQSQyyyTt5RT35nNqVpDft3hmegQN9p9.nd1rig/9VgolhNNlNgsk.Bz3Q5/:17153:0:99999:7::: [root@linuxelearn ~]#

In the above example after locking the user account by using usermod command. The single exclamation(!) sign after username called rahul ,confirmed the account is locked.

Note: if user passwd is not set and if we use usermod command to lock the account,it will show double exclamation sign

Unlocking a user account:

Unlock the above account

#passwd –u <username>

#passwd –u rahul

[root@linuxelearn ~]# passwd -u rahul Unlocking password for user rahul. passwd: Success [root@linuxelearn ~]#

#usermod  -U rahul

Ans verify it in /etc/shadow file, it shows exclamation mark before user account or try login as rahul

[root@linuxelearn ~]# usermod -U rahul [root@linuxelearn ~]# tail /etc/shadow rpcuser:!!:17026:::::: nfsnobody:!!:17026:::::: pulse:!!:17026:::::: gdm:!!:17026:::::: sshd:!!:17026:::::: tcpdump:!!:17026:::::: user:$6$kYw9IHnXahbyylyd$.fMwQf.WnzN7ftRawlOYPHAXsYZ3JvfOjawESWYBA8sWv413yfqqfWcdGXOcPoN6PFyXUmrh452c4XS2chJj30:17026:0:99999:7::: rahul:$6$IfqyPCtQ$v5275VCBDdM5iecTfWBVvs4gOClXyEiauVHS7Aa9861cpwo3GKAQnyYuNdK4O85Pr9QS8HW5fJvTUn9pCGWhg1:17027:0:99999:7::: nagios:$6$9YMaBpCe$U4puQbI98S.epxe21aiwOnpTBLEYl/jfAXfdkUzIEw75Cw/WIvGAt254QiBEBf3lZ6niwAJJwAFyf6u/XAEso1:17037:2:7:1:0:17040: pooja:$6$SM3See4e$Yk1lSTk8G09zvrIYZv0W13hIolfQSQyyyTt5RT35nNqVpDft3hmegQN9p9.nd1rig/9VgolhNNlNgsk.Bz3Q5/:17153:0:99999:7::: [root@linuxelearn ~]#

Observe in both pictures that once the account is unlocked the exclamation is gone.

You Must Have To Read This....

• Linux interview question and answers..
• How to Change Permission of Files and Directories in Unix/Linux
• What is the filesystem in linux ~ Unix and Linux Filesystem in detail Hierarchy system
• How to Update newly created partition – How to Formatting a partition with file system

Please Comment if you like the post and If you have any Suggestion also......