nginx fails to start due to left Apache configuration files from Kloxo panel: nginx: [emerg] bind() to 203.0.113.2:80 failed (98: Address already in use)

Symptoms

• After enabling nginx with the command plesk sbin nginxmng -e, it is failed to start:

  # service nginx status
  ● nginx.service - Startup script for nginx service
  Loaded: loaded (/usr/lib/systemd/system/nginx.service; enabled; vendor preset: disabled)
  Active: failed (Result: exit-code) since Cts 2018-02-10 18:54:45 +03; 10s ago
  nginx[11996]: nginx: [emerg] bind() to 203.0.113.2:80 failed (98: Address already in use)
  nginx[11996]: nginx: [emerg] bind() to 192.0.2.2:80 failed (98: Address already in use)
  nginx[11996]: nginx: [emerg] bind() to 203.0.113.2:443 failed (98: Address already in use)
  nginx[11996]: nginx: [emerg] bind() to 192.0.2.2:443 failed (98: Address already in use)
  nginx[11996]: nginx: [emerg] still could not bind()
  systemd[1]: nginx.service: control process exited, code=exited status=1
  systemd[1]: Failed to start Startup script for nginx service.
  systemd[1]: Unit nginx.service entered failed state.
  systemd[1]: nginx.service failed.

• Apache listens both on backend ports (7080 and 7081) and on the frontend ones (80 and 443):

  # netstat -tulpn | grep 80
  tcp      0    0  0.0.0.0:8880   0.0.0.0:*   LISTEN 1121/sw-cp-server:
  tcp6     0    0  :::80          :::*        LISTEN 11876/httpd
  tcp6     0    0  :::8880        :::*        LISTEN 1121/sw-cp-server:
  tcp6     0    0  :::7080        :::*        LISTEN 11876/httpd

  # netstat -tulpn | grep 7081
  tcp6     0    0  :::7081        :::*        LISTEN 11876/httpd

  # netstat -tulpn | grep 443
  tcp      0    0  0.0.0.0:8443   0.0.0.0:*   LISTEN 1121/sw-cp-server:
  tcp6     0    0  :::443         :::*        LISTEN 11876/httpd
  tcp6     0    0  :::8443        :::*        LISTEN 1121/sw-cp-server:

• After repairing the web servers configuration with the command plesk repair web, the issue still persists.

• In the Apache configuration directory, the configuration file /etc/httpd/conf.d/~lxcenter.conf, which contains the following lines at the end of it:

  CONFIG_TEXT: Include /opt/configs/apache/conf/defaults/*.conf
  Include /opt/configs/apache/conf/domains/*.conf
  Include /opt/configs/apache/conf/customs/*.conf

• One of the configuration files at the mentioned locations contain instructions for Apache to listen on port 80 and 443.

Cause

Third-party hosting panel Kloxo (or one of its forks) was previously installed on the server, and its configuration files were not fully removed.

Resolution

1. Connect to the server using SSH.

2. Rename the found configuration file:

   # mv /etc/httpd/conf.d/~lxcenter.conf{,.bak}

3. Restart Apache to apply changes (on Debian and Ubuntu, the service is called apache2):

   # service httpd restart

4. Start nginx:

   # service nginx start