What are the unsupported Kexalgorithms and Ciphers in FIPS mode enabled?

Solution Verified - Updated -


  • One of the KexAlgorithms configuration in /etc/ssh/sshd_config file is causing issues with FIPS.
root@example ~]# sshd -T | grep -i kex
"curve25519-sha256" is not allowed in FIPS mode
/etc/ssh/sshd_config line 180: Bad SSH2 KexAlgorithms 'curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256'.

root@example ~]# sshd -T | grep -i kex
/etc/ssh/sshd_config line 182: Bad SSH2 cipher spec 'chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com'.


  • Red Hat Enterprise Linux 7
  • Openssh

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