Convention for using ports in the 100-105 range

Question

Is there a conventions for using/not using ports in the 100-105 range for e.g. webservices?

Most browsers seem to block these for security reasons.

Update

The "most browser" statement is based on a mac at several locations but possibly a firewall issue as stated in the answers below.

Answer 1

Ports <= 1024 are typically reserved as "well known ports", meaning that they are used for commodity services which are commonly used. These services often are run in higher security contexts.

Browsers don't typically block anything without help from another entity. When you get a "blocked" message from your browser it usually means that there's a firewall or other gateway somewhere that's restricting the access.