Memcached is a service that can improve website performance by reducing the number times the database has to be queried. Infor CRM (formerly Saleslogix) uses memcached on its web server for exactly this purpose. Unfortunately, the memcached service does not offer much security, and leaving a server with memcached exposed to the internet allows hackers access to that server’s memcached service. Memcached uses port 11211, so it is important that an Infor CRM web server not be reachable on port 11211 from the internet.
In the Infor CRM documentation, it mentions that port 11211 need to be open for the Saleslogix cache server to work. This advice applies only to the machine itself. So, if you are using Windows Firewall (or some other security) on the Infor CRM web server itself, you would need to have port 11211 open. Port 11211 must be closed on the firewall that connects the Infor CRM web server to the outside internet. (If other web servers are behind the same hardware firewall, you’ll want port 11211 blocked for them as well.) If you have your Infor CRM web server connected directly to the internet, with no hardware firewall: you probably shouldn’t have been doing that in the first place, but you really need to stop now and get it behind a firewall.
The short version: make sure your Infor CRM web server is behind a firewall that blocks traffic on port 11211.