cleanup SSH key details

doc/ssh/README.md

@@ -13,7 +13,7 @@ read [this nice tutorial by DigitalOcean](https://www.digitalocean.com/community
 
 ## Locating an existing SSH key pair
 
-Before generating a new SSH key check if your system already has one
+Before generating a new SSH key pair check if your system already has one
 at the default location by opening a shell, or Command Prompt on Windows,
 and running the following command:
 
@@ -23,43 +23,49 @@ and running the following command:
 type %userprofile%\.ssh\id_rsa.pub
 ```
 
-**GNU/Linux / macOS / PowerShell:**
+**Git Bash on Windows / GNU/Linux / macOS / PowerShell:**
 
 ```bash
 cat ~/.ssh/id_rsa.pub
 ```
 
 If you see a string starting with `ssh-rsa` you already have an SSH key pair
-and you can skip the next step **Generating a new SSH key pair**
-and continue onto **Copying your public SSH key to the clipboard**.
+and you can skip the generate portion of the next section and skip to the copy
+to clipboard step.
 If you don't see the string or would like to generate a SSH key pair with a
 custom name continue onto the next step.
 
+>
+**Note:** Public SSH key may also be named as follows:
+- `id_dsa.pub`
+- `id_ecdsa.pub`
+- `id_ed25519.pub`
+
 ## Generating a new SSH key pair
 
-1. To generate a new SSH key, use the following command:
+1. To generate a new SSH key pair, use the following command:
 
-    **GNU/Linux / macOS:**
+    **Git Bash on Windows / GNU/Linux / macOS:**
 
     ```bash
-    ssh-keygen -t rsa -C "GitLab" -b 4096
+    ssh-keygen -t rsa -C "your.email@example.com" -b 4096
     ```
 
     **Windows:**
 
-    On Windows you will need to download
+    Alternatively on Windows you can download
     [PuttyGen](http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html)
-    and follow this [documentation article][winputty] to generate a SSH key pair.
+    and follow [this documentation article][winputty] to generate a SSH key pair.
 
-1. Next, you will be prompted to input a file path to save your key pair to.
+1. Next, you will be prompted to input a file path to save your SSH key pair to.
 
     If you don't already have an SSH key pair use the suggested path by pressing
-    enter. Using the suggested path will allow your SSH client
-    to automatically use the key pair with no additional configuration.
+    enter. Using the suggested path will normally allow your SSH client
+    to automatically use the SSH key pair with no additional configuration.
 
-    If you already have a key pair with the suggested file path, you will need
-    to input a new file path and declare what host this key pair will be used
-    for in your `.ssh/config` file, see **Working with non-default SSH key pair paths**
+    If you already have a SSH key pair with the suggested file path, you will need
+    to input a new file path and declare what host this SSH key pair will be used
+    for in your `.ssh/config` file, see [**Working with non-default SSH key pair paths**](#working-with-non-default-ssh-key-pair-paths)
     for more information.
 
 1. Once you have input a file path you will be prompted to input a password to
@@ -68,12 +74,12 @@ custom name continue onto the next step.
    pressing enter.
 
      >**Note:**
-     If you want to change the password of your key, you can use `ssh-keygen -p <keyname>`.
+     If you want to change the password of your SSH key pair, you can use
+     `ssh-keygen -p <keyname>`.
 
-1. The next step is to copy the public key as we will need it afterwards.
+1. The next step is to copy the public SSH key as we will need it afterwards.
 
-    To copy your public key to the clipboard, use the appropriate code for your
-    operating system below:
+    To copy your public SSH key to the clipboard, use the appropriate code below:
 
     **macOS:**
 
@@ -93,7 +99,7 @@ custom name continue onto the next step.
     type %userprofile%\.ssh\id_rsa.pub | clip
     ```
 
-    **Windows PowerShell:**
+    **Git Bash on Windows / Windows PowerShell:**
 
     ```bash
     cat ~/.ssh/id_rsa.pub | clip
@@ -101,7 +107,7 @@ custom name continue onto the next step.
 
 1. The final step is to add your public SSH key to GitLab.
 
-    Navigate to the 'SSH Keys' tab in you 'Profile Settings'.
+    Navigate to the 'SSH Keys' tab in your 'Profile Settings'.
     Paste your key in the 'Key' section and give it a relevant 'Title'.
     Use an identifiable title like 'Work Laptop - Windows 7' or
     'Home MacBook Pro 15'.
@@ -109,14 +115,30 @@ custom name continue onto the next step.
     If you manually copied your public SSH key make sure you copied the entire
     key starting with `ssh-rsa` and ending with your email.
     
+1. Optionally you can test your setup by running `ssh -T git@example.com`
+   (replacing `example.com` with your GitLab domain) and verifying that you
+   receive a `Welcome to GitLab` message.
+
 ## Working with non-default SSH key pair paths
 
 If you used a non-default file path for your GitLab SSH key pair,
-you must configure your SSH client to find your GitLab SSH private key
-for connections to your GitLab server (perhaps gitlab.com).
+you must configure your SSH client to find your GitLab private SSH key
+for connections to your GitLab server (perhaps `gitlab.com`).
+
+For your current terminal session you can do so using the following commands
+(replacing `other_id_rsa` with your private SSH key):
+
+**Git Bash on Windows / GNU/Linux / macOS:**
+
+```bash
+eval $(ssh-agent -s)
+ssh-add ~/.ssh/other_id_rsa
+```
 
-For OpenSSH clients this is configured in the `~/.ssh/config` file.
-Below are two example host configurations using their own key:
+To retain these settings you'll need to save them to a configuration file.
+For OpenSSH clients this is configured in the `~/.ssh/config` file for some
+operating systems.
+Below are two example host configurations using their own SSH key:
 
 ```
 # GitLab.com server
@@ -140,8 +162,8 @@ That's why it needs to uniquely map to a single user.
 
 ## Deploy keys
 
-Deploy keys allow read-only access to multiple projects with a single SSH
-key.
+Deploy keys allow read-only or read-write (if enabled) access to one or
+multiple projects with a single SSH key pair.
 
 This is really useful for cloning repositories to your Continuous
 Integration (CI) server. By using deploy keys, you don't have to setup a
@@ -150,7 +172,8 @@ dummy user account.
 If you are a project master or owner, you can add a deploy key in the
 project settings under the section 'Deploy Keys'. Press the 'New Deploy
 Key' button and upload a public SSH key. After this, the machine that uses
-the corresponding private key has read-only access to the project.
+the corresponding private SSH key has read-only or read-write (if enabled) 
+access to the project.
 
 You can't add the same deploy key twice with the 'New Deploy Key' option.
 If you want to add the same key to another project, please enable it in the
@@ -166,6 +189,18 @@ project.
 
 ### Eclipse
 
-How to add your ssh key to Eclipse: https://wiki.eclipse.org/EGit/User_Guide#Eclipse_SSH_Configuration
+How to add your SSH key to Eclipse: https://wiki.eclipse.org/EGit/User_Guide#Eclipse_SSH_Configuration
 
 [winputty]: https://the.earth.li/~sgtatham/putty/0.67/htmldoc/Chapter8.html#pubkey-puttygen
+
+## Troubleshooting
+
+If on Git clone you are prompted for a password like `git@gitlab.com's password:`
+something is wrong with your SSH setup.
+
+- Ensure that you generated your SSH key pair correctly and added the public SSH
+  key to your GitLab profile
+- Try manually registering your private SSH key using `ssh-agent` as documented 
+  earlier in this document
+- Try to debug the connection by running `ssh -Tv git@example.com`
+  (replacing `example.com` with your GitLab domain)