User Management
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useradd username |
create a user |
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groupadd groupname |
create a group |
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userdel username |
delete user |
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groupdel groupname |
delete group |
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usermod username |
modify user |
Important files
/etc/passwd
/etc/group
/etc/shadow
Examples
useradd -g superheros -s /bin/bash -c "User Description" -m -d /home/spiderman spiderman
(Creates spiderman in group superheros)
usermod -G superheros spiderman
(adds spiderman to superheros group)
chgrp -R superheros spiderman
(change the group owner of user to superheros)
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cat /etc/passwd |
display users, passwords (x=encrypted), UserID, GroupID, etc. |
defaults file located in /etc/login.defs
Example:
chage -m 5 -M 90 -W 10 -I 3 -E 20656 babubutt
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-d |
(lastchanged) days since 01/01/1970 that password was last changed |
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-m |
minimum number of days between password changes |
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-M |
maximum number of days before user must change password |
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-W |
number of days before password is to expire before user is warned |
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-I |
number of days after password expires that account is disabled |
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-E |
days since 01/01/1970 that account is disabled (account end date) |
grep babu /etc/shadow
babubutt:!:20626:5:90:10:3:20656:
Switching users and sudo access
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su - |
switch to root |
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su - username |
switch user |
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sudo |
perform action as super user |
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visudo |
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Add user to sudoers
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su - |
switch to root |
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usermod -aG wheel nsotelo |
adds nsotelo to wheel group |
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grep wheel /etc/group |
verify |
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su - nsotelo |
switch back to nsotelo |
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sudo fdisk -l |
run sudo command to confirm access |