1.8. Creating a custom unit file by using the second instance of the sshd service

If you need to configure and run multiple instances of a service, you can create copies of the original service configuration files and modify certain parameters to avoid conflicts with the primary instance of the service.

Procedure

To create a second instance of the sshd service:

Create a copy of the sshd_config file that the second daemon will use:
```
# cp /etc/ssh/sshd{,-second}_config
```
Edit the sshd-second_config file created in the previous step to assign a different port number and PID file to the second daemon:
```
Port 22220
PidFile /var/run/sshd-second.pid
```
See the sshd_config(5) manual page for more information about Port and PidFile options. Make sure the port you choose is not in use by any other service. The PID file does not have to exist before running the service, it is generated automatically on service start.

Create a copy of the systemd unit file for the sshd service:

# cp /usr/lib/systemd/system/sshd.service /etc/systemd/system/sshd-second.service

Alter the created sshd-second.service:

Modify the Description option:

Description=OpenSSH server second instance daemon

Add sshd.service to services specified in the After option, so that the second instance starts only after the first one has already started:
```
After=syslog.target network.target auditd.service sshd.service
```
Remove the ExecStartPre=/usr/sbin/sshd-keygen line, the first instance of sshd includes key generation.
Add the -f /etc/ssh/sshd-second_config parameter to the sshd command, so that the alternative configuration file is used:
```
ExecStart=/usr/sbin/sshd -D -f /etc/ssh/sshd-second_config $OPTIONS
```

After the modifications, the sshd-second.service unit file contains the following settings:

[Unit]
Description=OpenSSH server second instance daemon
After=syslog.target network.target auditd.service sshd.service

[Service]
EnvironmentFile=/etc/sysconfig/sshd
ExecStart=/usr/sbin/sshd -D -f /etc/ssh/sshd-second_config $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
KillMode=process
Restart=on-failure
RestartSec=42s

[Install]
WantedBy=multi-user.target

If using SELinux, add the port for the second instance of sshd to SSH ports, otherwise the second instance of sshd will be rejected to bind to the port:
```
# semanage port -a -t ssh_port_t -p tcp 22220
```
Enable sshd-second.service to start automatically on boot:
```
# systemctl enable sshd-second.service
```
Verify if the sshd-second.service is running by using the systemctl status command.
Verify if the port is enabled correctly by connecting to the service:
```
$ ssh -p 22220 user@server
```
Make sure you configure the firewall to allow connections to the second instance of sshd.

1.8. Creating a custom unit file by using the second instance of the sshd service

学习

尝试、购买和销售

社区

关于红帽文档

让开源更具包容性

關於紅帽

Theme

Red Hat legal and privacy links

Red Hat legal and privacy links