CertiGuide to Security+  9  Chapter 3:  Infrastructure Security (Domain 3.0; 20%)       9  3.5  Security Baselines            9  3.5.3  Application Hardening

3.5.3.5  DNS Servers 1 3.5.3.7  File/Print Servers

NNTP servers handle the distribution of Usenet News. The NNTP (or Net News Transfer Protocol) uses port 119, so if you need to provide NNTP access to clients outside your network, make sure you allow incoming connections to port 119 on your NNTP server.

Through an NNTP server, users can read and post news “articles” which are then made available to other sites participating in Usenet through bulk transfers of batches of articles among cooperating sites. (Yes, you read that right; there WAS peer-to-peer before Napster!)

NNTP software tends to be fairly complex, and security holes are discovered in various implementations from time to time, with results including an attacker obtaining system administrator access to the news server, creating a denial of service situation, reconfiguration of the news server, etc., so do keep up with patches.

NNTP originally controlled access based on the host from which users connected (or they allowed everyone, anywhere, access). When most users read news from multi-user UNIX machines, this model worked well enough, but with the advent of single-user workstations and dynamically assigned IP addresses, became difficult to manage.

Add the problem of users making inappropriate posts, and even “forging” news articles (making it look like someone else posted an article they created), and news server suppliers began to place more emphasis on authenticating those who connect to them.

Some require users to authenticate themselves before access is provided, and some don’t. If possible, run a news server that requires authentication and takes steps to ensure that articles are not submitted with forged identity information.

Based on the provided authentication information, users can be authorized to read news, post or bulk transfer news (which allows the user to upload/download entire sets of multiple articles, a capability which is usually only needed for servers). Most commonly, you would only allow the first two privileges, unless a peer server with whom you exchange news used the user ID in question.

3.5.3.5  DNS Servers 1 3.5.3.7  File/Print Servers