Diagnose Networking Issues Using urlpoke.jar

Sonatype products are heavily dependent on the Hypertext Transport Protocol (HTTP) and Transport Layer Security (TLS). These protocols need to successfully navigate through complex organizational network infrastructures and occasionally experience problems which are better debugged in isolation from a Sonatype product experiencing a related problem.

Sonatype products are also Java based and use common HTTP client shared libraries. Sometimes particular issues need to be replicated with specific Java or HTTP client versions.

To aid this advanced debugging, Sonatype Support has written a tool offering a Java based pseudo client which can help isolate the root cause of a networking related problem.

Download urlpoke.jar

When should I use urlpoke?

The tool is typically used on the advice of Sonatype support staff.

While trivial to use, it should be considered one of the last resorts needed after the more common debugging techniques of examining product logs have not provided enough info.

What does urlpoke do?

The urlpoke.jar is a simple Java based program can make a socket connection and/or HTTP/TLS connection to a remote host that you specify. Features include:

  • plain TCP and secure TLS socket connections
  • plain http and secure https HEAD, GET connections
  • http proxy server support
  • basic http proxy and target URL authentication

Why use urlpoke instead of ...?

This tool was created by Sonatype support staff to help diagnose common networking problems our server products encounter. Sometimes debugging problems in a production server product can be simplified by using a standalone client making similar requests the server products make. Experience has also shown that some networking issues are only reproducible using specific Java client libraries and versions that closely match those used by Sonatype products.


The urlpoke.jar requires Java 8 or greater. Typically you want to ensure that the exact same Java runtime used to run a Sonatype product experiencing a problem is also used to execute urlpoke.

Ideally run this tool on the same host and user where the Sonatype product experiencing the problem is located. This reduces the variables which could be contributing to a product problem.

How to use it

Use the java command to launch the jar file with program arguments. Typically all output from stderr/stdout is redirected to a file (Unix / Windows), then the contents of the resulting file should be examined in a text editor to diagnose problems.

Unix Terminal Example

java -jar urlpoke.jar https://www.sonatype.com &> urlpoke.log

Windows Command Prompt Example

java -jar urlpoke.jar https://www.sonatype.com 1> urlpoke.log 2>&1

Program Help

The jar is a self contained executable. To get help, simply launch it without arguments, or specify the -? argument:

java -jar urlpoke.jar 
==[12:06:40:809] [INFO] org.sonatype.support.urlpoke.URLPoke - 2020-06-12 15:06:40,808+0000
==[12:06:40:813] [INFO] org.sonatype.support.urlpoke.URLPoke - 61a5f55492a28bdb1c7685ff2aa2747aa0db1487 (202006121206)
==[12:06:40:938] [INFO] org.sonatype.support.urlpoke.URLPoke - Java Cryptography Extension (JCE) detected? - true (2147483647)
==[12:06:40:938] [ERROR] org.sonatype.support.urlpoke.URLPoke - Main parameters are required ("<target URI>")
==[12:06:40:940] [ERROR] org.sonatype.support.urlpoke.URLPoke - Usage: java -jar urlpoke.jar [options] <target URI>
    -p, --proxy
      HTTP Proxy, format <host:port>. Host and port is required.
    -U, --proxy-user
      Credentials for HTTP proxy, format <username:password>
      Log all output to the specified file.
      HTTP methods for poke. Supported: [HEAD, GET].
      Default: [HEAD, GET]
      HTTP client preferred auth schemes. Supported: 
      Default: [NTLM, Negotiate, Digest, Basic]
      Do not log effective system properties.
      Default: false
      Do not log HTTP headers.
      Default: false
      Sets system prop javax.net.debug=ssl
      Default: false
      Sets system prop javax.net.debug=all
      Default: false
    -h, -?, --help
      Show this help screen
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