.sshd.hmac: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/sbin/.sshd.hmac - from package: openssh-server

You may install the required package with command yum install {package}
Error in other languages:
.sshd.hmac: bevel nie gevind nie
.sshd.hmac: comandă negăsită
.sshd.hmac: comando não encontrado
.sshd.hmac: commande introuvable
.sshd.hmac: command not found
.sshd.hmac: käsku ei ole
.sshd.hmac: không tìm thấy lệnh
.sshd.hmac: komanda nerasta
.sshd.hmac: Kommando nicht gefunden.
.sshd.hmac: kommandot finns inte
.sshd.hmac: komut yok
.sshd.hmac: nie znaleziono polecenia
.sshd.hmac: níor aimsíodh an t-ordú
.sshd.hmac: no se encontró la orden
.sshd.hmac: no s'ha trobat l'ordre
.sshd.hmac: opdracht niet gevonden
.sshd.hmac: parancs nem található
.sshd.hmac: perintah tidak ditemukan
.sshd.hmac: príkaz nenájdený
.sshd.hmac: příkaz nenalezen
.sshd.hmac: команда не найдена
.sshd.hmac: командата не е открита
.sshd.hmac: 命令找不到
.sshd.hmac: コマンドが見つかりません