> Source: [sk182982](https://support.checkpoint.com/results/sk/sk182982)

# sk182982 - Cannot disable a Key Exchange (KEX) Cipher

| Property | Value |
|----------|-------|
| Solution ID | sk182982 |
| Date Created | 2025-01-15 |
| Last Modified | 2025-01-19 |
| Technical Level | Advanced |
| Products | Security Gateway |
| Versions | R81.20 |

## Symptoms

- * After disabling a Key Exchange (KEX) cipher with the command: "`set ssh server kex <Cipher> off`" as described in [sk172189](https://support.checkpoint.com/results/sk/sk172189), the cipher is still active.

* The output of the "`sshd -T -C 'user=admin,addr=::1' | grep -i kex`" command shows that the cipher is still enabled after setting it off.

## Cause

The file */etc/ssh/sshd_config* has immutable ('i') extended attribute. When this attribute is present, the file cannot be modified.

To find if the attribute is on, run the command:

`# lsattr /etc/ssh/sshd_config`

Example output:

![](https://sc1.checkpoint.com/sc/SolutionsStatics/sk182982/root-cause202501151616191.png)

## Solution

This solution requires authentication. Please log in to view the full solution.

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