Red Hat Enterprise Linux - Allow Root Login From a Specific IP Address Only

Title: Red Hat Enterprise Linux - Allow Root Login From a Specific IP Address Only
Object Name: mmr_kc-0119626
Document Type: Support Information
Original owner: KCS - Linux
Disclosure level: Public
Version state: final
Environment
FACT:Red Hat Enterprise Linux
Questions/Symptoms
GOAL:Restrict root SSH login to a single IP address
Cause
CAUSE:
Answer/Solution
FIX:This can be accomplished with the use of PAM access controls.  There are two steps:

1. In /etc/pam.d/sshd, add the following line:

account    required     pam_access.so


2. In /etc/security/access.conf, set up root access controls by adding the following two lines at the end of the file:

+ : root : IP_address
- : root : ALL


Replace "IP_address" with the IP address of the system from which root logins will be allowed.  Note that there is a space before and after each colon.  The first line allows root access from the specified IP address; the second line denies root access from everywhere else.  The order of these two lines is significant.  This will take effect immediately with no need to reboot or restart any daemons.


Login attempts that are blocked by this check will be logged in /var/log/secure:

Jul 15 16:51:42 hostname sshd[18241]: fatal: Access denied for user root by PAM account configuration

This method of access control is very flexible and powerful.  For example, if you should need to add a second allowed host at some point in the future, simply add its IP address to the first line:

+ : root : IP_address_1 IP_address_2
- : root : ALL


There are many other options, which are well documented within the access.conf file itself or its reference page.
0 (0)
Article Rating (No Votes)
Rate this article
Attachments
There are no attachments for this article.
Comments
There are no comments for this article. Be the first to post a comment.
Full Name
Email Address
Security Code Security Code
Related Articles RSS Feed
socat: Linux / UNIX TCP Port Forwarder
Viewed 9875 times since Tue, Aug 6, 2019
How setting the TZ environment variable avoids thousands of system calls
Viewed 10380 times since Mon, May 21, 2018
Create a Linux Swap File
Viewed 3198 times since Fri, Jun 8, 2018
Super Grub2 Disk
Viewed 3575 times since Wed, May 22, 2019
How to recover error - Audit error: dispatch err (pipe full) event lost
Viewed 26347 times since Tue, Aug 6, 2019
Secure Secure Shell
Viewed 11150 times since Fri, Aug 21, 2020
RHEL: Manually encrypting a filesystem with LUKS
Viewed 4017 times since Sun, May 27, 2018
Linux - How to perform I/O performance test with dd command
Viewed 6242 times since Fri, Jun 8, 2018
Use Fail2ban to Secure Your Server
Viewed 15186 times since Fri, Jul 5, 2019
Linux 16 Useful Bandwidth Monitoring Tools to Analyze Network Usage in Linux
Viewed 15720 times since Mon, Sep 21, 2020