We have all been there. You deploy a new integration, fire the test, and get the single most unhelpful error message in the history of computing:

Remote host closed connection during handshake.

That’s it. No reason. No error code. Just silence.

Junior engineers start randomly swapping certificates. Senior engineers start Googling cipher suites. Principal Architects turn on the lights.

The Java Virtual Machine (JVM) has a built-in "God Mode" for SSL/TLS networking: -Djavax.net.debug. It logs every single packet, byte, and decision made during the handshake. But where you enable it depends on which era of webMethods you are running.

The "Old World" (Integration Server Monolith)

If you are still running a classic on-premise IS (v10.15 or older) via the Tanuki Service Wrapper, you live in the custom_wrapper.conf file.

  • Location: .../profiles/IS/configuration/custom_wrapper.conf

  • The Fix:

    wrapper.java.additional.999=-Djavax.net.debug=ssl,handshake

    (Pro Tip: Ensure 999 is a unique index).

The "New World" (Microservices Runtime / IWHI)

In the containerized world of IBM webMethods Hybrid Integration, there is no wrapper. The IS process is the PID 1 of the container. If you look for custom_wrapper.conf, you are looking for a ghost.

Instead, you must inject the flag directly into the JVM startup environment.

  • The Mechanism: The JAVA_CUSTOM_OPTS environment variable.

  • The Fix (Docker/Kubernetes):

    env:
  - name: JAVA_CUSTOM_OPTS
    value: "-Djavax.net.debug=ssl,handshake"

Reading the Matrix (What to Look For)

Once you trigger the error, your logs will explode with text. Don’t panic. You are looking for The Breakup:

1. The ClientHello (The Offer)

*** ClientHello, TLSv1.2
Cipher Suites: [TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384, ...]

  • The Director's Check: Does the client offer a protocol your server accepts? If they send TLSv1 and you require TLSv1.2, the conversation ends here.

2. The ServerHello (The Agreement)

*** ServerHello, TLSv1.2
Cipher Suite: TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384

  • The Director's Check: If you see a ClientHello but no ServerHello, your server looked at the menu and decided it couldn't eat anything. You have a Cipher Mismatch.

3. The Certificate Chain (The ID Card)

*** Certificate chain
chain [0] = [ Subject: CN=api.company.com ... ]
chain [1] = [ Issuer: CN=DigiCert Global Root CA ... ]

  • The Director's Check: The most common "Cloud Migration" failure is a missing Intermediate CA. If the chain stops at the Leaf, the client will hang up.

The Lesson

The architecture changes (Monolith → Microservice), but the physics stay the same. You cannot architect a Zero Trust network if you don't understand the handshake that builds trust.

Stop guessing. Turn on the logs. See the matrix.

Further Reading: From the Console to the Architecture

1. The "God Mode" Manual: Oracle JSSE Reference Guide

  • The Link: Troubleshooting Security (Oracle Docs)

  • Why read it: This is the official documentation for javax.net.debug. It lists every available option beyond just ssl,handshake (like record, keygen, and session). If you really want to know what the JVM is thinking, start here.

2. The Physics of the Handshake: "High Performance Browser Networking" (O'Reilly)

  • The Link: TLS Handshake Chapter

  • Why read it: Ilya Grigorik’s breakdown is widely considered the gold standard for visualizing the cost of latency in a handshake. It explains why we care about the difference between a 1-RTT and 2-RTT handshake in distributed systems.

3. The "New World" Spec: RFC 8446 (TLS 1.3)

  • The Link: The Transport Layer Security (TLS) Protocol Version 1.3

  • Why read it: Real Architects read RFCs. TLS 1.3 fundamentally changes the handshake (encrypting the certificate exchange itself), which makes debugging harder. If you are moving to modern mesh architectures, you need to understand how this breaks your old packet capture habits.

4. Container Configuration: Passing Env Vars in Kubernetes

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