roles/common: Remove Encrypt-and-MAC modes from Ubuntu 20.04 sshd_config

Recommended by ssh-audit, but also generally the concensus for a few
years that Encrypt-and-MAC is hard to get right. OpenSSH has several
Encrypt-then-MAC schemes available so we can use those.

See: https://www.daemonology.net/blog/2009-06-24-encrypt-then-mac.html
This commit is contained in:
Alan Orth 2021-07-22 12:48:12 +03:00
parent 9b7a31ebf9
commit 9ea14de6f5
Signed by: alanorth
GPG Key ID: 0FB860CC9C45B1B9

View File

@ -128,7 +128,7 @@ PasswordAuthentication yes
# ... but with ciphers and MACs with < 256 bits removed, as NSA's Suite B now
# does away with these! See: https://www.nsa.gov/ia/programs/suiteb_cryptography/index.shtml
Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes256-ctr
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com
KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group-exchange-sha256
{% if ssh_allowed_users is defined and ssh_allowed_users %}