There is a Centos 7 machine where this falls after 80 loops target="same host" while [ $i -ne 500 ];do echo -e "$i" ssh -p 22 root@${target} "ls / 1>/dev/null && exit;" ((i++)) done The loop does not fail against Ubuntu boxes. kindly let me know if I am doing something wrong. This is my sshd_config sshd -T port 22 addressfamily any listenaddress [::]:22 listenaddress 0.0.0.0:22 usepam no logingracetime 120 x11displayoffset 10 maxauthtries 20 maxsessions 100 clientaliveinterval 0 clientalivecountmax 3 streamlocalbindmask 0177 permitrootlogin without-password ignorerhosts yes ignoreuserknownhosts no hostbasedauthentication no hostbasedusesnamefrompacketonly no pubkeyauthentication yes kerberosauthentication no kerberosorlocalpasswd yes kerberosticketcleanup yes gssapiauthentication no gssapicleanupcredentials yes passwordauthentication no kbdinteractiveauthentication yes challengeresponseauthentication yes printmotd yes printlastlog yes x11forwarding no x11uselocalhost yes permittty yes permituserrc yes strictmodes no tcpkeepalive yes permitemptypasswords no compression yes gatewayports no usedns no allowtcpforwarding yes allowagentforwarding yes disableforwarding no allowstreamlocalforwarding yes streamlocalbindunlink no fingerprinthash SHA256 exposeauthinfo no pidfile /var/run/sshd.pid xauthlocation /usr/bin/xauth ciphers chacha20-poly1305@xxxxxxxxxxx,aes128-ctr,aes192-ctr,aes256-ctr, aes128-gcm@xxxxxxxxxxx,aes256-gcm@xxxxxxxxxxx macs umac-64-etm@xxxxxxxxxxx,umac-128-etm@xxxxxxxxxxx, hmac-sha2-256-etm@xxxxxxxxxxx,hmac-sha2-512-etm@xxxxxxxxxxx, hmac-sha1-etm@xxxxxxxxxxx,umac-64@xxxxxxxxxxx,umac-128@xxxxxxxxxxx ,hmac-sha2-256,hmac-sha2-512,hmac-sha1 banner none forcecommand none chrootdirectory none trustedusercakeys none revokedkeys none authorizedprincipalsfile none versionaddendum none authorizedkeyscommand none authorizedkeyscommanduser none authorizedprincipalscommand none authorizedprincipalscommanduser none hostkeyagent none kexalgorithms curve25519-sha256,curve25519-sha256@xxxxxxxxxx ,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,diffie-hellman-group14-sha1 casignaturealgorithms ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa hostbasedacceptedkeytypes ecdsa-sha2-nistp256-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp384-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp521-cert-v01@xxxxxxxxxxx,ssh-ed25519-cert-v01@xxxxxxxxxxx, rsa-sha2-512-cert-v01@xxxxxxxxxxx,rsa-sha2-256-cert-v01@xxxxxxxxxxx, ssh-rsa-cert-v01@xxxxxxxxxxx ,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa hostkeyalgorithms ecdsa-sha2-nistp256-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp384-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp521-cert-v01@xxxxxxxxxxx,ssh-ed25519-cert-v01@xxxxxxxxxxx, rsa-sha2-512-cert-v01@xxxxxxxxxxx,rsa-sha2-256-cert-v01@xxxxxxxxxxx, ssh-rsa-cert-v01@xxxxxxxxxxx ,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa pubkeyacceptedkeytypes ecdsa-sha2-nistp256-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp384-cert-v01@xxxxxxxxxxx, ecdsa-sha2-nistp521-cert-v01@xxxxxxxxxxx,ssh-ed25519-cert-v01@xxxxxxxxxxx, rsa-sha2-512-cert-v01@xxxxxxxxxxx,rsa-sha2-256-cert-v01@xxxxxxxxxxx, ssh-rsa-cert-v01@xxxxxxxxxxx ,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa rdomain none loglevel INFO syslogfacility AUTH authorizedkeysfile .ssh/authorized_keys hostkey /etc/ssh/ssh_host_rsa_key hostkey /etc/ssh/ssh_host_ecdsa_key hostkey /etc/ssh/ssh_host_ed25519_key allowusers root authenticationmethods any subsystem sftp /usr/libexec/sftp-server maxstartups 500:30:500 permittunnel no ipqos af21 cs1 rekeylimit 0 0 permitopen any permitlisten any permituserenvironment no _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev