diff --git a/README.md b/README.md
index 539cf8a..520050f 100644
--- a/README.md
+++ b/README.md
@@ -28,10 +28,10 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Setup ssh session
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
 ```
 
-To get the connection string, just open the `Checks` tab in your Pull Request or Run and scroll to the bottom. There you can connect either directly per SSH or via a web based terminal. The connection string is also logged inside workflow logs.
+To get the connection string, just open the `Checks` tab in your Pull Request or Run and scroll to the bottom. There you can connect directly per SSH, or via a web based terminal when `limit-access-to-actor` is `false`. The connection string is also logged inside workflow logs.
 
 ![screenshots](https://github.com/WarpBuilds/action-debugger/assets/9110203/2e1ce772-285f-4a4e-a41a-d12054d8960e)
 ![check](https://github.com/WarpBuilds/action-debugger/assets/9110203/d8cb31ef-5044-4f39-a391-a198ec09ce39)
@@ -66,7 +66,7 @@ jobs:
     steps:
       # Enable ssh debugging of manually-triggered workflows if the input option was provided
       - name: Setup interactive ssh session
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
         if: ${{ github.event_name == 'workflow_dispatch' && inputs.debug_enabled }}
 ```
 
@@ -89,7 +89,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Setup interactive ssh session
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
         with:
           detached: true
 ```
@@ -119,7 +119,7 @@ jobs:
     - uses: actions/checkout@v4
     - name: Setup ssh session
       id: debugger
-      uses: Warpbuilds/action-debugger@v1.3
+      uses: Warpbuilds/action-debugger@v2
       with:
         detached: true
         
@@ -145,7 +145,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: Setup ssh session
-      uses: Warpbuilds/action-debugger@v1.3
+      uses: Warpbuilds/action-debugger@v2
       with:
         sudo: false
 ```
@@ -163,7 +163,7 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Setup interactive ssh session
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
         timeout-minutes: 15
 ```
 
@@ -184,7 +184,7 @@ jobs:
       - uses: actions/checkout@v4
       - name: Setup interactive ssh session
         if: ${{ failure() }}
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
 ```
 <!--
 {% endraw %}
@@ -192,7 +192,9 @@ jobs:
 
 ## Use registered public SSH key(s)
 
-If [you have registered one or more public SSH keys with your GitHub profile](https://docs.github.com/en/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account), ssh will be started such that only those keys are authorized to connect, otherwise anybody can connect to the ssh session. If you want to require a public SSH key to be installed with the ssh session, no matter whether the user who started the workflow has registered any in their GitHub profile, you will need to configure the setting `limit-access-to-actor` to `true`, like so:
+By default, only the user who started the workflow can connect, using the public SSH keys [registered with their GitHub profile](https://docs.github.com/en/github/authenticating-to-github/adding-a-new-ssh-key-to-your-github-account). If that user has no public SSH key, the step fails and no session starts. The web shell is also turned off.
+
+To allow anyone with the connection string to connect, set `limit-access-to-actor` to `false`. Do not do this on a public repository, because anyone who can read the job log can then open a shell on the runner.
 
 ```yaml
 name: CI
@@ -203,9 +205,9 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Setup interactive ssh session
-        uses: Warpbuilds/action-debugger@v1.3
+        uses: Warpbuilds/action-debugger@v2
         with:
-          limit-access-to-actor: true
+          limit-access-to-actor: false
 ```
 
 If the registered public SSH key is not your default private SSH key, you will need to specify the path manually, like so: `ssh -i <path-to-key> <ssh-connection-string>`.
@@ -223,7 +225,7 @@ jobs:
     steps:
     - uses: actions/checkout@v4
     - name: Setup ssh session
-      uses: Warpbuilds/action-debugger@v1.3
+      uses: Warpbuilds/action-debugger@v2
       with:
         tmate-server-host: ssh.tmate.io
         tmate-server-port: 22
@@ -242,7 +244,7 @@ jobs:
   build:
     runs-on: [self-hosted, linux]
     steps:
-    - uses: Warpbuilds/action-debugger@v1.3
+    - uses: Warpbuilds/action-debugger@v2
       with:
         install-dependencies: false
 ```
@@ -260,7 +262,7 @@ jobs:
     steps:
     - uses: msys2/setup-msys2@v2
       id: setup-msys2
-    - uses: Warpbuilds/action-debugger@v1.3
+    - uses: Warpbuilds/action-debugger@v2
       with:
         msys2-location: ${{ steps.setup-msys2.outputs.msys2-location }}
 ```
diff --git a/action.yml b/action.yml
index a47a599..bbcff11 100644
--- a/action.yml
+++ b/action.yml
@@ -19,9 +19,9 @@ inputs:
     required: false
     default: "true"
   limit-access-to-actor:
-    description: "Whether to authorize only the public SSH keys of the user triggering the workflow (defaults to true if the GitHub profile of the user has a public SSH key)"
+    description: "Whether to authorize only the public SSH keys of the user triggering the workflow. The session fails to start if the user has no public SSH key. Set to false to allow anyone with the session address to connect."
     required: false
-    default: "auto"
+    default: "true"
   detached:
     description: "In detached mode, the workflow job will continue while the ssh session is active"
     required: false
diff --git a/detached/action.yml b/detached/action.yml
index 2df030e..90f2d77 100644
--- a/detached/action.yml
+++ b/detached/action.yml
@@ -19,9 +19,9 @@ inputs:
     required: false
     default: "true"
   limit-access-to-actor:
-    description: "Whether to authorize only the public SSH keys of the user triggering the workflow (defaults to true if the GitHub profile of the user has a public SSH key)"
+    description: "Whether to authorize only the public SSH keys of the user triggering the workflow. The session fails to start if the user has no public SSH key. Set to false to allow anyone with the session address to connect."
     required: false
-    default: "auto"
+    default: "true"
   detached:
     description: "In detached mode, the workflow job will continue while the ssh session is active"
     required: false
diff --git a/lib/index.js b/lib/index.js
index 8a6658f..6964fa8 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -35242,7 +35242,7 @@ function core_error(message, properties = {}) {
  * @param properties optional properties to add to the annotation.
  */
 function warning(message, properties = {}) {
-    command_issueCommand('warning', utils_toCommandProperties(properties), message instanceof Error ? message.toString() : message);
+    issueCommand('warning', toCommandProperties(properties), message instanceof Error ? message.toString() : message);
 }
 /**
  * Adds a notice issue
@@ -41232,9 +41232,8 @@ async function run() {
 
     let newSessionExtra = "";
     let tmateSSHDashI = "";
-    let publicSSHKeysWarning = "";
     const limitAccessToActor = getInput("limit-access-to-actor");
-    if (limitAccessToActor === "true" || limitAccessToActor === "auto") {
+    if (limitAccessToActor !== "false") {
       const { actor, apiUrl } = github_context;
       const auth = getInput("github-token");
       const octokit = new dist_src_Octokit({
@@ -41246,12 +41245,9 @@ async function run() {
         username: actor,
       });
       if (keys.data.length === 0) {
-        if (limitAccessToActor === "auto")
-          publicSSHKeysWarning = `No public SSH keys found for ${actor}; continuing without them even if it is less secure (please consider adding an SSH key, see https://docs.github.com/en/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account)`;
-        else
-          throw new Error(
-            `No public SSH keys registered with ${actor}'s GitHub profile`
-          );
+        throw new Error(
+          `No public SSH keys registered with ${actor}'s GitHub profile. Add one at https://github.com/settings/keys, or set limit-access-to-actor: false to allow anyone with the session address to connect.`
+        );
       } else {
         const sshPath = external_path_default().join(external_os_default().homedir(), ".ssh");
         await external_fs_default().promises.mkdir(sshPath, { recursive: true });
@@ -41354,9 +41350,6 @@ async function run() {
       core_debug("Entering detached mode");
 
       let message = "";
-      if (publicSSHKeysWarning) {
-        message += `::warning::${publicSSHKeysWarning}\n`;
-      }
       if (tmateWeb) {
         message += `::notice::Web shell: ${tmateWeb}\n`;
       }
@@ -41383,9 +41376,6 @@ async function run() {
 
     core_debug("Entering main loop");
     while (true) {
-      if (publicSSHKeysWarning) {
-        warning(publicSSHKeysWarning);
-      }
       if (tmateWeb) {
         info(`Web shell: ${tmateWeb}`);
       }
diff --git a/src/index.js b/src/index.js
index 320b2d6..71d9502 100644
--- a/src/index.js
+++ b/src/index.js
@@ -155,9 +155,8 @@ export async function run() {
 
     let newSessionExtra = "";
     let tmateSSHDashI = "";
-    let publicSSHKeysWarning = "";
     const limitAccessToActor = core.getInput("limit-access-to-actor");
-    if (limitAccessToActor === "true" || limitAccessToActor === "auto") {
+    if (limitAccessToActor !== "false") {
       const { actor, apiUrl } = github.context;
       const auth = core.getInput("github-token");
       const octokit = new Octokit({
@@ -169,12 +168,9 @@ export async function run() {
         username: actor,
       });
       if (keys.data.length === 0) {
-        if (limitAccessToActor === "auto")
-          publicSSHKeysWarning = `No public SSH keys found for ${actor}; continuing without them even if it is less secure (please consider adding an SSH key, see https://docs.github.com/en/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account)`;
-        else
-          throw new Error(
-            `No public SSH keys registered with ${actor}'s GitHub profile`
-          );
+        throw new Error(
+          `No public SSH keys registered with ${actor}'s GitHub profile. Add one at https://github.com/settings/keys, or set limit-access-to-actor: false to allow anyone with the session address to connect.`
+        );
       } else {
         const sshPath = path.join(os.homedir(), ".ssh");
         await fs.promises.mkdir(sshPath, { recursive: true });
@@ -277,9 +273,6 @@ export async function run() {
       core.debug("Entering detached mode");
 
       let message = "";
-      if (publicSSHKeysWarning) {
-        message += `::warning::${publicSSHKeysWarning}\n`;
-      }
       if (tmateWeb) {
         message += `::notice::Web shell: ${tmateWeb}\n`;
       }
@@ -306,9 +299,6 @@ export async function run() {
 
     core.debug("Entering main loop");
     while (true) {
-      if (publicSSHKeysWarning) {
-        core.warning(publicSSHKeysWarning);
-      }
       if (tmateWeb) {
         core.info(`Web shell: ${tmateWeb}`);
       }
diff --git a/src/index.test.js b/src/index.test.js
index 51cf640..0bc1d29 100644
--- a/src/index.test.js
+++ b/src/index.test.js
@@ -39,13 +39,16 @@ jest.mock(
   }),
   { virtual: true }
 );
+const mockListPublicKeysForUser = jest.fn(async () => ({
+  data: [{ key: "ssh-ed25519 AAAA test-user" }],
+}));
 jest.mock(
   "@octokit/rest",
   () => ({
     __esModule: true,
     Octokit: class {
       users = {
-        listPublicKeysForUser: async () => ({ data: [] }),
+        listPublicKeysForUser: mockListPublicKeysForUser,
       };
     },
   }),
@@ -124,7 +127,7 @@ describe("Tmate GitHub integration", () => {
     Object.defineProperty(process, "platform", {
       value: "win32",
     });
-    core.getInput.mockReturnValueOnce("false");
+    core.getInput.mockReturnValueOnce("false").mockReturnValueOnce("false");
     const customConnectionString = "foobar";
     execShellCommand.mockReturnValue(Promise.resolve(customConnectionString));
     await run();
@@ -244,6 +247,44 @@ describe("Tmate GitHub integration", () => {
 
     expect(core.setFailed).not.toHaveBeenCalled();
   });
+
+  it("should authorize only the actor's public SSH keys by default", async () => {
+    core.getInput.mockReturnValue("");
+
+    await run();
+
+    expect(core.setFailed).not.toHaveBeenCalled();
+    expect(execShellCommand).toHaveBeenCalledWith(
+      expect.stringContaining("-a \"")
+    );
+  });
+
+  it("should fail when the actor has no public SSH keys", async () => {
+    core.getInput.mockReturnValue("");
+    mockListPublicKeysForUser.mockResolvedValueOnce({ data: [] });
+
+    await run();
+
+    expect(core.setFailed).toHaveBeenCalledWith(
+      expect.objectContaining({
+        message: expect.stringContaining("No public SSH keys registered with test-user"),
+      })
+    );
+    expect(execShellCommand).not.toHaveBeenCalledWith(
+      expect.stringContaining("new-session")
+    );
+  });
+
+  it("should allow anyone to connect when limit-access-to-actor is false", async () => {
+    core.getInput.mockImplementation((name) =>
+      name === "limit-access-to-actor" ? "false" : ""
+    );
+
+    await run();
+
+    expect(core.setFailed).not.toHaveBeenCalled();
+    expect(mockListPublicKeysForUser).not.toHaveBeenCalled();
+  });
   it("should validate correct tmate options", async () => {
     // Check for the happy path first.
     core.getInput.mockImplementation(function (opt) {