Some folks have been having issues getting all the Maven repositories set up properly in Nexus for Apache Camel. Here's my working Nexus config and settings.xml - hope it helps!
Nexus config (admittedly polluted with repos from other projects...)
I found my Nexus config in /opt/sonatype-work/nexus/conf. I'm not sure what happens when you copy in a new Nexus config file so you should probably make a copy of the sonatype-work directory first :)