Check Jira version

grab the ajs-version-number from the login page source code

$ curl <http://JIRA/login.jsp> | grep 'ajs-version-number'
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
100 39884    0 39884    0     0   599k      0 --:--:-- --:--:-- --:--:--  608k
<meta name="ajs-version-number" content="8.20.4">

Also can get from JIRA:8080/rest/api/latest/serverInfo

$ curl <http://JIRA:8080/rest/api/latest/serverInfo>
{
  "baseUrl": "<https://REDACTED>",
  "version": "8.20.4",
  "versionNumbers": [
    8,
    20,
    4
  ],
  "deploymentType": "Server",
  "buildNumber": 820004,
  "buildDate": "2022-01-18T00:00:00.000+0200",
  "databaseBuildNumber": 820004,
  "scmInfo": "REDACTED",
  "serverTitle": "Jira"
}

Check user jira permissions

If you have access to a Jira user you can query the REST API to check the permissions:

https://COMPANY_NAME.atlassian.net/rest/api/3/mypermissions?permissions=ADD_COMMENTS,ADMINISTER,ADMINISTER_PROJECTS,ASSIGNABLE_USER,ASSIGN_ISSUES,BROWSE_PROJECTS,BULK_CHANGE,CLOSE_ISSUES,CREATE_ATTACHMENTS,CREATE_ISSUES,CREATE_PROJECT,CREATE_SHARED_OBJECTS,DELETE_ALL_ATTACHMENTS,DELETE_ALL_COMMENTS,DELETE_ALL_WORKLOGS,DELETE_ISSUES,DELETE_OWN_ATTACHMENTS,DELETE_OWN_COMMENTS,DELETE_OWN_WORKLOGS,EDIT_ALL_COMMENTS,EDIT_ALL_WORKLOGS,EDIT_ISSUES,EDIT_OWN_COMMENTS,EDIT_OWN_WORKLOGS,LINK_ISSUES,MANAGE_GROUP_FILTER_SUBSCRIPTIONS,MANAGE_SPRINTS_PERMISSION,MANAGE_WATCHERS,MODIFY_REPORTER,MOVE_ISSUES,RESOLVE_ISSUES,SCHEDULE_ISSUES,SET_ISSUE_SECURITY,SYSTEM_ADMIN,TRANSITION_ISSUES,USER_PICKER,VIEW_AGGREGATED_DATA,VIEW_DEV_TOOLS,VIEW_READONLY_WORKFLOW,VIEW_VOTERS_AND_WATCHERS,WORK_ON_ISSUES

Example output:

curl https://COMPANY_NAME.atlassian.net/rest/api/3/mypermissions?permissions=ADD_COMMENTS,ADMINISTER,ADMINISTER_PROJECTS,ASSIGNABLE_USER,ASSIGN_ISSUES,BROWSE_PROJECTS,BULK_CHANGE,CLOSE_ISSUES,CREATE_ATTACHMENTS,CREATE_ISSUES,CREATE_PROJECT,CREATE_SHARED_OBJECTS,DELETE_ALL_ATTACHMENTS,DELETE_ALL_COMMENTS,DELETE_ALL_WORKLOGS,DELETE_ISSUES,DELETE_OWN_ATTACHMENTS,DELETE_OWN_COMMENTS,DELETE_OWN_WORKLOGS,EDIT_ALL_COMMENTS,EDIT_ALL_WORKLOGS,EDIT_ISSUES,EDIT_OWN_COMMENTS,EDIT_OWN_WORKLOGS,LINK_ISSUES,MANAGE_GROUP_FILTER_SUBSCRIPTIONS,MANAGE_SPRINTS_PERMISSION,MANAGE_WATCHERS,MODIFY_REPORTER,MOVE_ISSUES,RESOLVE_ISSUES,SCHEDULE_ISSUES,SET_ISSUE_SECURITY,SYSTEM_ADMIN,TRANSITION_ISSUES,USER_PICKER,VIEW_AGGREGATED_DATA,VIEW_DEV_TOOLS,VIEW_READONLY_WORKFLOW,VIEW_VOTERS_AND_WATCHERS,WORK_ON_ISSUES | jq . 
{
  "permissions": {
    "ADD_COMMENTS": {
      "key": "ADD_COMMENTS",
      "name": "Add Comments",
      "type": "PROJECT",
      "description": "Ability to comment on issues."
    },
    "ADMINISTER": {
      "key": "ADMINISTER",
      "name": "Administer Jira",
      "type": "GLOBAL",
      "description": "Create and administer projects, issue types, fields, workflows, and schemes for all projects. Users with this permission can perform most administration tasks, except: managing users, importing data, and editing system email settings."
    },
    "ADMINISTER_PROJECTS": {
      "key": "ADMINISTER_PROJECTS",
      "name": "Administer Projects",
      "type": "PROJECT",
      "description": "Ability to administer a project in Jira."
    },
    "ASSIGNABLE_USER": {
      "key": "ASSIGNABLE_USER",
      "name": "Assignable User",
      "type": "PROJECT",
      "description": "Users with this permission may be assigned to issues."
    },

check if a dashboard is externally accessible

Query the REST API for all the dashboards and grab the id

https://COMPANY_NAME.atlassian.net/rest/api/3/dashboard

Query each dashboard for information (without any auth):

curl https://COMPANY_NAME.atlassian.net/rest/api/3/dashboard/172722

If successful:

curl https://COMPANY_NAME.atlassian.net/rest/api/3/dashboard/172 | jq .
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100  2190    0  2190    0     0   7966      0 --:--:-- --:--:-- --:--:--  7963
{
  "description": "",
  "id": "172",
  "isFavourite": false,
  "name": "DASHBOARD_NAME_REDACTED",
  "owner": {
    "self": "https://COMPANY_NAME.atlassian.net/rest/api/3/user?accountId=**************5f714d",
    "displayName": "OWNER_NAME_REDACTED",
    "active": true,
    "accountId": "**************5f714d",
    

Not publicly available:

 curl https://COMPANY_NAME.atlassian.net/rest/api/3/dashboard/172722 | jq .                                   
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    80    0    80    0     0    313      0 --:--:-- --:--:-- --:--:--   314
{
  "errorMessages": [
    "The dashboard with id '172722' does not exist."
  ],
  "errors": {}
}