Example of creating a virtual host based on Apache port

[root@localhost httpd]# vim /etc/httpd/conf/httpd.conf
Comment out the following line in the main configuration file #DocumentRoot "/var/www/html"

Find the Listen line and add a line Listen 8080 based on the original line Listen 80 
Listen 81

[root@localhost httpd]#vim /etc/httpd/conf.d/virtualhost.conf
<VirtualHost 192.168.87.131:80>
  DocumentRoot "/var/www/a"
  ServerName www.a.com
</VirtualHost>
<VirtualHost 192.168.87.131:8080>
  DocumentRoot "/var/www/b"
  ServerName www.b.com
</VirtualHost>
<VirtualHost 192.168.87.131:81
  DocumentRoot "/var/www/c"
  ServerName www.c.com
</VirtualHost>

[root@localhost conf.d]# cd /var/www 
[root@localhost www]# mkdir abc
[root@localhost www]# echo welcome to www.a.com >> ./a/index.html
[root@localhost www]# echo welcome to www.b.com >> ./b/index.html
[root@localhost www]# echo welcome to www.c.com >> ./c/index.html

[root@localhost ~]#systemctl restart httpd