Why "service sshd start" command can not return to command prompt? - linux

Question

I'm install a new CentOS7, its sshd service works fine. Then I download the source code of openssh7.5p1, build it and install it to the default directory "/usr/local/sbin/sshd". I want to use it to replace the system's sshd.
I modify the file "/usr/lib/systemd/system/sshd.service", change following line:
old:
ExecStart=/usr/sbin/sshd $OPTIONS
new:
ExecStart=/usr/local/sbin/sshd $OPTIONS
After that, type command "service sshd start", the command can not return and seems hang up. Looks as follows:
[root#localhost ~]# service sshd start
Redirecting to /bin/systemctl start sshd.service
I press Ctl+C to terminate the command. Then use command "netstat -ntlp" to find that the "sshd" already started, not sure why the "service sshd start" can not return to prompt.
[root#localhost ~]# netstat -ntlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1/systemd
tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN 2443/dnsmasq
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 63144/sshd
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1043/cupsd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1815/master
tcp6 0 0 :::111 :::* LISTEN 1/systemd
tcp6 0 0 :::22 :::* LISTEN 63144/sshd
tcp6 0 0 ::1:631 :::* LISTEN 1043/cupsd
tcp6 0 0 ::1:25 :::* LISTEN 1815/master
I try to start sshd manually, it works fine, the sshd started successfully(no any warning message) and the command return immediately. The command as follows:
[root#localhost ~]# /usr/local/sbin/sshd -f /etc/ssh/sshd_config
Any help is appreciated. Let me know if you want to known more information. Thanks.

Answer 1

How about tinkering With type in your .service ?
have you tried to set it to idle ?
maybe systemd waits to receive a message from sshd and seems to hang..