How to remediate the Vul Deprecated SSH Cryptographic Settings which was flagged via scanning on PRD

OS version: Oracle Linux server 8.8 using kernel 5

Avoid using deprecated cryptographic settings.  

Use best practices when configuring SSH. 

Refer to Security of Interactive and Automated Access Management Using Secure Shell (SSH) ( https://csrc.nist.gov/publications/detail/nistir/7966/final )  . 

Settings currently considered deprecated: 

1.Ciphers using CFB or OFB: 

These are considered uncommon and deprecated due to vulnerabilities when compared to newer cipher chaining modes such as CTR or GCM. 

 

2.RC4 cipher (arcfour, arcfour128, arcfour256): 

The RC4 cipher is no longer considered secure and exhibits cryptographic bias. 

 

3.Ciphers with a 64-bit block size (DES, 3DES, Blowfish, IDEA, CAST): 

These ciphers may be vulnerable to birthday attacks (Sweet32).