In Linux we can copy files and directories around with the ‘cp’ command. Here we will demonstrate some common examples in which ‘cp’ can be used.
Tag Archives: Linux - Page 8
Linux How To: Join Two Files – Append One File To Another
Posted by Jarrod Farncomb
on July 13, 2016
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With the Bash shell in Linux it is quite simple to append the contents of one file to another, here we will cover how to perform file concatenation.
Linux How To: Add User To Group
Posted by Jarrod Farncomb
on July 6, 2016
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In Linux we can modify a local user account with the ‘usermod’ command. Here we will cover some examples of using the various syntax options with usermod in order to modify existing user accounts in Linux, specifically to add them into a group.
Linux How To: Add A User Account
Posted by Jarrod Farncomb
on June 29, 2016
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In Linux we can create a new user account with the ‘useradd’ command. Here we will cover some examples of using the various syntax options with useradd in order to create a new local user account in Linux.
How To Use Kerberos to Control Access to NFS Network Shares
Posted by Jarrod Farncomb
on June 22, 2016
7 comments
By default NFS is not very secure, there’s no real authentication and access is granted based on hostname or IP address, information is sent over the network in plain text, and it’s also fairly easy to fake your UID/GID.
By making use of Kerberos we can secure NFS as this provides authentication, encryption and integrity.
How To Configure Linux To Authenticate Using Kerberos
Posted by Jarrod Farncomb
on June 15, 2016
26 comments
Kerberos is an authentication protocol that can provide secure network login or SSO for various services over a non-secure network. Kerberos works with the concept of tickets which are encrypted and can help reduce the amount of times passwords need to be sent over the network.
These tickets are issued throughout the Kerberos realm by a centralised key distribution center (KDC). Here we will cover how to setup a KDC and obtain a Kerberos ticket from a client system in CentOS Linux.
Produce And Deliver System Utilization Reports (processor, memory, disk, and network)
Posted by Jarrod Farncomb
on June 8, 2016
1 comment
The sysstat package in Linux automatically logs various system resource information, including processor, memory, disk and network.
We can process these logs with the ‘sadf’ command in order to generate basic reports which outline system resource usage over a defined period of time.
How To Provide SMB/CIFS Network Shares For Group Collaboration
Posted by Jarrod Farncomb
on June 1, 2016
1 comment
Samba is an open source implementation of the server message block (SMB) and common internet file system (CIFS) protocols, it allows us to access Windows file share resources from Linux.
With Samba we can export specific directories within a file system over the network to other Windows or Linux clients, allowing us to share various files over the network between different operating systems.
Here we’re going to cover setting up a samba file share that allows for group collaboration. Users within a particular group will be able to create content within a samba share that other users within the same group will be able to access and modify.
How To Provide SMB/CIFS Network Shares To Specific Clients
Posted by Jarrod Farncomb
on May 25, 2016
7 comments
Samba is an open source implementation of the server message block (SMB) and common internet file system (CIFS) protocols, it allows us to access Windows file share resources from Linux.
With Samba we can export specific directories within a file system over the network to other Windows or Linux clients, allowing us to share various files over the network between different operating systems.
It is important to configure this properly and secure it as much as possible so that only the required clients and users have access to the SMB/CIFS share, otherwise it may be possible for anyone to mount and access the data.
To do this we are going to use the /etc/samba/smb.conf file on the SMB/CIFS server and lock down shares to only be accessible by specific IP addresses and user accounts.
How To Clear The SSSD Cache In Linux
Posted by Jarrod Farncomb
on April 13, 2016
5 comments
The System Security Services Daemon (SSSD) provides access to identity and authentication providers. Basically rather than relying on locally configured authentication, SSSD is used to lookup its local cache. The entries within this cache may come from different remote identity providers, such as an LDAP directory, FreeIPA, or Active Directory for example.
SSSD caches the results of users and credentials from these remote locations so that if the identity provider goes offline, the user credentials are still available and users can still login. This helps to improve performance and facilitates scalability with a single user that can login over many systems, rather than using local accounts everywhere.
The cached results can potentially be problematic if the stored records become stale and are no longer in sync with the identity provider, so it is important to know how to flush the SSSD cache to fix various problems and update the cache.
Here we’ll cover a couple of different methods to flush out the SSSD cache.