How do you configure maven to ignore repositories specified in POM files?

As a workaround, define another repository in your settings.xml with the same ID (is it oss.sonatype.org, defined in jetty-parent:19, that's the problem?) and point it at your repo. Maven will use that definition in favour of the one in the pom.

There's an open issue filed against Maven (MNG-3056) to allow this to be configured so only your repo would be used; in general, if you have a local repository, that would be the behaviour you would want.

That's a great answer Joe. Thank you. I was looking for it for quite some time.

I just quote an example, in which I had the same problem as Nathan.

I use a Maven enterprise repository (Nexus or Artifactory) and I am behind a proxy, that means that I cannot download directly (and do not want to) from any other repositories than mine.
Jasper reports net.sf.jasperreports:jasperreports:6.2.0 defines in its pom a couple of repositories.

<groupId>net.sf.jasperreports</groupId>
<artifactId>jasperreports</artifactId>
<version>6.2.0</version>
...
<repositories>
    <repository>
        <id>jasperreports</id>
        <url>http://jasperreports.sourceforge.net/maven2</url>
    </repository>
    <repository>
        <id>jaspersoft-third-party</id>
        <url>http://jaspersoft.artifactoryonline.com/jaspersoft/third-party-ce-artifacts/</url>
    </repository>
</repositories>

This causes the following exception:

C:\my-project>mvn verify
[INFO] Scanning for projects...

[INFO] Building my-project 1.0.0-SNAPSHOT
[INFO] 
Downloading: http://mynexus/nexus/content/groups/ch-public/com/lowagie/itext/2.1.7.js4/itext-2.1.7.js4.pom
Downloading: http://jasperreports.sourceforge.net/maven2/com/lowagie/itext/2.1.7.js4/itext-2.1.7.js4.pom
Downloading: http://jaspersoft.artifactoryonline.com/jaspersoft/third-party-ce-artifacts/com/lowagie/itext/2.1.7.js4/itext-2.1.7.js4.pom
[INFO] BUILD FAILURE
[INFO] Could not resolve dependencies for project ... :
Failed to collect dependencies at net.sf.jasperreports:jasperreports:jar:6.2.0 -> 
com.lowagie:itext:jar:2.1.7.js4: Failed to read artifact descriptor for com.lowagie:itext:jar:2.1.7.js4: 
Could not transfer artifact com.lowagie:itext:pom:2.1.7.js4 
from/to jasperreports (http://jasperreports.sourceforge.net/maven2): 
Connect to jasperreports.sourceforge.net:80 [jasperreports.sourceforge.net/216.34.181.96] 
failed: Connection timed out: 

The solution as described by Joe is: In global settings.xml (C:/maven-installation/conf/settings.xml) or private settings.xml (~/.m2/settings.xml) add the following profile:

<profiles>
    <profile>
        <id>ignore-repositories</id>
        <activation>
            <activeByDefault>false</activeByDefault>
        </activation>
        <repositories>
            <repository>
                <id>jasperreports</id>
                <url>http://mynexus/nexus/content/groups/ch-public/
                </url>
                <releases>
                    <enabled>true</enabled>
                </releases>
                <snapshots>
                    <enabled>false</enabled>
                </snapshots>
            </repository>
            <repository>
                <id>jaspersoft-third-party</id>
                <url>http://mynexus/nexus/content/groups/ch-public/
                </url>
                <releases>
                    <enabled>true</enabled>
                </releases>
                <snapshots>
                    <enabled>false</enabled>
                </snapshots>
            </repository>
        </repositories>
    </profile>
</profiles>

Important: the repository id in the profiles (jasperreports , jaspersoft-third-party) matches exactly the id of the repository used in pom.xml - in this case the pom.xml of net.sf.jasperreports:jasperreports:6.2.0

Do not forget to add the "external" repositories to the "proxy" list of your Maven Enterprise Repository