Memcached was not designed for authentication and is protected only by firewalls and similar mechanisms.
Viable options include the following:
Set up an SSL tunnel between memcached and instances of Tomcat.
Use SASL for authentication.
Use the Lucene server’s firewall to allow access only from the Vibe servers that run Vibe Tomcat.
For example:
At the terminal prompt on the Lucene server, run the following command for each Vibe server that needs access:
iptables -A INPUT -s ip_of_allowed_server -p tcp --dport 11211 -j ACCEPT Where ip_of_allowed_server is the IP address of one of the Vibe servers needing access.
For example:
iptables -A INPUT -s 192.168.1.61 -p tcp --dport 11211 -j ACCEPT
Repeat Step 1 until all of the Vibe servers that need access are allowed to communicate through the Lucene server’s firewall.
Run the following command to block access by all other servers:
iptables -A INPUT -s 0.0.0.0/0 -p tcp --dport 11211 -j DROP