hard-coded environment variables, removed deprecated variables, updated cipher orders

Author: k4yt3x

sshd_config

@@ -1,7 +1,11 @@
 # Name: K4YT3X Hardened OpenSSH Configuration
 # Author: K4YT3X
 # Date Created: October 5, 2020
-# Last Updated: October 8, 2020
+# Last Updated: October 10, 2020
+
+# Licensed under the GNU General Public License Version 3 (GNU GPL v3),
+#   available at: https://www.gnu.org/licenses/gpl-3.0.txt
+# (C) 2020 K4YT3X
 
 ########## Binding ##########
 
@@ -19,12 +23,17 @@
 ########## Features ##########
 
 # accept locale-related environment variables
-AcceptEnv LANG LC_*
+AcceptEnv LANG LC_CTYPE LC_NUMERIC LC_TIME LC_COLLATE LC_MONETARY LC_MESSAGES
+AcceptEnv LC_PAPER LC_NAME LC_ADDRESS LC_TELEPHONE LC_MEASUREMENT
+AcceptEnv LC_IDENTIFICATION LC_ALL LANGUAGE
+AcceptEnv XMODIFIERS
 
 # disallow ssh-agent forwarding to prevent lateral movement
 AllowAgentForwarding no
 
 # prevent TCP ports from being forwarded over SSH tunnels
+# **please be aware that disabling TCP forwarding does not prevent port forwarding**
+# any user with an interactive login shell can spin up his/her own instance of sshd
 AllowTcpForwarding no
 
 # prevent StreamLocal (Unix-domain socket) forwarding
@@ -44,10 +53,6 @@ PermitTunnel no
 # suppress MOTD
 PrintMotd no
 
-# use kernel sandbox mechanisms where possible in unprivileged processes
-# systrace on OpenBSD, Seccomp on Linux, seatbelt on MacOSX/Darwin, rlimit elsewhere
-UsePrivilegeSeparation sandbox
-
 # disable X11 forwarding since it is not necessary
 X11Forwarding no
 
@@ -93,8 +98,8 @@ PubkeyAuthentication yes
 # explicitly define cryptography algorithms to avoid the use of weak algorithms
 Ciphers chacha20-poly1305@openssh.com,aes256-gcm@openssh.com,aes128-gcm@openssh.com,aes256-ctr,aes192-ctr,aes128-ctr
 HostKeyAlgorithms rsa-sha2-512,rsa-sha2-256,ssh-ed25519
-KexAlgorithms curve25519-sha256@libssh.org,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
-MACs umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com
+KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group-exchange-sha256
+MACs hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,umac-128-etm@openssh.com
 
 ########## Connection Preferences ##########