Disabling ARC4 Weak Algorithm (SSH Weak Algorithms Supported)

How to Mitigate SSH weak algorithm caused by ARC4 in 

OS: Redhat Linux

Description

Nessus / Open VAS has detected that the remote SSH server is configured to use the Arcfour stream cipher or no cipher at all. RFC 4253 advises against using Arcfour due to an issue with weak keys.

Solution:

To disable ARC4  go to /etc/ssh/sshd_config  and add the following entry 

# restrict ciphers to exclude arcfour

Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc

Now restart the sshd 

 service sshd restart

 This should mitigate the identified vulnerability and remove RC4.

you can use the command  sshd -T |grep ciphers to check the current supported cipher versions running .