error: package org.jboss.netty.channel.socket.nio

Which JAR contains org.jboss.netty.channel.socket.nio? I'm not using maven or ivy, just ant (from netbeans).

Ant compile gives:

-do-compile:
    [javac] Compiling 4 source files to /home/thufir/NetBeansProjects/EchoClient/build/classes
    [javac] /home/thufir/NetBeansProjects/EchoClient/src/net/bounceme/dur/netty/client/ObjectEchoClient.java:3: error: package org.jboss.netty.channel.socket.nio does not exist
    [javac] import org.jboss.netty.channel.socket.nio.NioClientSocketChannelFactory;

In the classpath is:

thufir@dur:~/NetBeansProjects/EchoClient/nbproject$ 
thufir@dur:~/NetBeansProjects/EchoClient/nbproject$ head -n 58 project.properties | tail -n 29
endorsed.classpath=
excludes=
file.reference.netty-all-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/all-in-one/netty-all-4.0.21.Final-sources.jar
file.reference.netty-all-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/all-in-one/netty-all-4.0.21.Final.jar
file.reference.netty-buffer-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-buffer-4.0.21.Final-sources.jar
file.reference.netty-buffer-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-buffer-4.0.21.Final.jar
file.reference.netty-codec-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-4.0.21.Final-sources.jar
file.reference.netty-codec-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-4.0.21.Final.jar
file.reference.netty-codec-http-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-http-4.0.21.Final-sources.jar
file.reference.netty-codec-http-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-http-4.0.21.Final.jar
file.reference.netty-codec-socks-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-socks-4.0.21.Final-sources.jar
file.reference.netty-codec-socks-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-codec-socks-4.0.21.Final.jar
file.reference.netty-common-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-common-4.0.21.Final-sources.jar
file.reference.netty-common-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-common-4.0.21.Final.jar
file.reference.netty-example-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-example-4.0.21.Final-sources.jar
file.reference.netty-example-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-example-4.0.21.Final.jar
file.reference.netty-handler-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-handler-4.0.21.Final-sources.jar
file.reference.netty-handler-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-handler-4.0.21.Final.jar
file.reference.netty-tcnative-1.1.30.Fork2-linux-x86_64.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-tcnative-1.1.30.Fork2-linux-x86_64.jar
file.reference.netty-tcnative-1.1.30.Fork2-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-tcnative-1.1.30.Fork2-sources.jar
file.reference.netty-transport-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-4.0.21.Final-sources.jar
file.reference.netty-transport-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-4.0.21.Final.jar
file.reference.netty-transport-rxtx-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-rxtx-4.0.21.Final-sources.jar
file.reference.netty-transport-rxtx-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-rxtx-4.0.21.Final.jar
file.reference.netty-transport-sctp-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-sctp-4.0.21.Final-sources.jar
file.reference.netty-transport-sctp-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-sctp-4.0.21.Final.jar
file.reference.netty-transport-udt-4.0.21.Final-sources.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-udt-4.0.21.Final-sources.jar
file.reference.netty-transport-udt-4.0.21.Final.jar=/home/thufir/jars/netty-4.0.21.Final/jar/netty-transport-udt-4.0.21.Final.jar
includes=**
thufir@dur:~/NetBeansProjects/EchoClient/nbproject$

Which was downloaded from:

http://netty.io/downloads.html

netty-4.0.21.Final.tar.bz2

I added each JAR from that download to the project. Yes, I realize it's not using the CLI javac classpath, but the JAR's are visible in the project, as well as in the output above.

I looked through some of the JAR's and was unable to find this specific class.

You seem to be trying to build an application developed against netty 3.x using netty 4.0. There have been API changes, including channel creation and bootstrap. Also, the package prefix changed from org.jboss.netty to io.netty reflecting the project status change.

Use the API documentation (which no longer documents NioClientSocketChannelFactory) corresponding to the release you're using and checkout the provided examples (netty-example-4.0.21.Final-sources.jar) to help port any code you have that's built against netty 3.x.