SSH Diffie-Hellman ¶
moduli of 2048 bits or greater¶
Take a copy of /etc/ssh/moduli and /etc/ssh/sshd_config file first
cp /etc/ssh/moduli /etc/ssh/moduli.backup
cp /etc/ssh/sshd_config /etc/ssh/sshd_config.backup
Delete lines from /etc/ssh/moduli where the 5th column is less than 2000.
awk '$5 > 2000' /etc/ssh/moduli > /usr/src/moduli
mv "/usr/src/moduli" /etc/ssh/moduli
Diffie-Hellman ¶
Add the following KexAlgorithms in /etc/ssh/sshd_config
KexAlgorithms ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256
Restart SSH service on the server¶
systemctl restart sshd