ACL for Incoming Traffic

Last changed: 2024-04-17

There is a firewall that blocks incoming traffic to the NREC instances and infrastructure. This is done to protect our users and their services running on NREC.

Some ports are completely blocked, meaning that traffic to those ports are not allowed from anywhere. For other ports, traffic from IP addresses belonging to Norwegian universities and colleges are allowed, and blocked from anywhere else.

Completely Blocked Ports

The following ports are completely blocked:

Port	Protocol	Service	Comment
23	All	telnet	Telnet is an unencrypted remote login service that should never be used. Use an encrypted service such as SSH instead
111	All	portmapper	The portmapper protocol is mostly used for NFS versions 2 and 3. It is vulnerable to DDoS attacks and should not be exposed to the internet
139	All	netbios-ssn	This port is used for SMB/CIFS services. Exposing SMB from NREC to the outside presents a wealth of security concerns
445	All	microsoft-ds	This port is used for SMB/CIFS services. Exposing SMB from NREC to the outside presents a wealth of security concerns
2049	All	nfs	Exposing NFS from NREC to the outside presents a lot of security concerns

Allowed only from Norwegian Universities and Colleges

The following ports are blocked, except from Norwegian universities and colleges.

Port	Protocol	Service	Comment
25	All	SMTP	Port used by mail servers. If not managed with great care, mail servers are easily exploited
53	All	Domain Name Service (DNS)	There are very few reasons why one would want to run DNS servers in NREC. An incorrectly configured DNS service could disrupt other services running on NREC
1186	All	MySQL Cluster	Database ports should never be open on the internet
1433	All	Microsoft SQL Server	Database ports should never be open on the internet
1434	All	Microsoft SQL Monitor	Database ports should never be open on the internet
3128	All	Squid Web Proxy	An exposed Squid service is a security concern and should not exist in NREC
3306	All	MySQL	Database ports should never be open on the internet
3389	All	RDP	Port used to grant graphical login access to Windows servers. Easily exploitable if the server is not patched aggressively
5432	All	PostgreSQL	Database ports should never be open on the internet
5900	All	VNC	Port used for VNC, which is easy to set up wrong and should not be exposed on the internet
6379	TCP	Redis noSQL database	Database ports should never be open on the internet
8080	All	“Configuration Port”	Port used by various web services (e.g. Tomcat) for configuration and admin access. Should not be open to the whole internet
8443	All	“Configuration Port”	Port used by various web services for configuration and admin access. Should not be open to the whole internet
9200	TCP	Elastisearch	The default port used by Elasticsearch for requests
27017	TCP	MongoDB noSQL database	Database ports should never be open on the internet