On a new CentOS 7/CloudLinux server, i had to get CloudLinux license support, but for some reason CloudLinux support can’t login to my server. It worked fine on Ubuntu 16.04. CloudLinux support sent following log, asked me to check.
[17:41]divanov@sshbox:~$ ssh -v root@SERVER-IP-HERE OpenSSH_5.3p1, OpenSSL 1.0.1e-fips 11 Feb 2013 debug1: Reading configuration data /home/clsupport/.ssh/config debug1: Applying options for * debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Executing proxy command: exec /usr/bin/sss_ssh_knownhostsproxy -p 22 SERVER-IP-HERE debug1: permanently_drop_suid: 500 debug1: identity file /home/clsupport/.ssh/identity type -1 debug1: identity file /home/clsupport/.ssh/identity-cert type -1 debug1: identity file /home/clsupport/.ssh/id_rsa type 1 debug1: identity file /home/clsupport/.ssh/id_rsa-cert type -1 debug1: identity file /home/clsupport/.ssh/id_dsa type 2 debug1: identity file /home/clsupport/.ssh/id_dsa-cert type -1 debug1: identity file /home/clsupport/.ssh/id_ecdsa type -1 debug1: identity file /home/clsupport/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6.1 debug1: match: OpenSSH_6.6.1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received no matching mac found: client hmac-sha1,umac-64@openssh.com,hmac-ripemd160 server hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
This is because CentOS 7 ssh server have removed some MAC for better security. But enabling them is fine for most.
This is fixed by editing
vi /etc/ssh/sshd_config
Find line
MACs hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256
Replace it with
MACs hmac-sha1,hmac-sha1-96,hmac-md5,hmac-sha2-512-etm@openssh.com,hmac-sha2-256-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-512,hmac-sha2-256,hmac-ripemd160
This will add following extra MACs.
hmac-sha1,hmac-sha1-96,hmac-md5,hmac-ripemd160
Now restart SSHD with
service sshd restart