diff --git a/app/controllers/concerns/epp_requestable.rb b/app/controllers/concerns/epp_requestable.rb
index 59d064644..05f39d93f 100644
--- a/app/controllers/concerns/epp_requestable.rb
+++ b/app/controllers/concerns/epp_requestable.rb
@@ -9,8 +9,8 @@ module EppRequestable
     authorize! :create, Epp::Server
     result = server.request(request_params[:payload])
     render_success(data: { xml: result.force_encoding('UTF-8') })
-  rescue StandardError
-    handle_non_epp_errors(nil, I18n.t('errors.messages.epp_conn_error'))
+  rescue StandardError => e
+    handle_non_epp_errors(nil, e.message.presence || I18n.t('errors.messages.epp_conn_error'))
   end
 
   private
diff --git a/app/controllers/concerns/error_and_log_handler.rb b/app/controllers/concerns/error_and_log_handler.rb
new file mode 100644
index 000000000..57f8c6b08
--- /dev/null
+++ b/app/controllers/concerns/error_and_log_handler.rb
@@ -0,0 +1,80 @@
+module ErrorAndLogHandler
+  extend ActiveSupport::Concern
+
+  included do
+    around_action :log_request
+  end
+
+  private
+
+  # rubocop:disable Metrics/MethodLength
+  def log_request
+    yield
+  rescue ActiveRecord::RecordNotFound
+    handle_record_not_found
+  rescue ActionController::ParameterMissing, Apipie::ParamMissing => e
+    handle_parameter_missing(e)
+  rescue Apipie::ParamInvalid => e
+    handle_param_invalid(e)
+  rescue CanCan::AccessDenied => e
+    handle_access_denied(e)
+  rescue Shunter::ThrottleError => e
+    handle_throttle_error(e)
+  ensure
+    create_repp_log
+  end
+  # rubocop:enable Metrics/MethodLength
+
+  def handle_record_not_found
+    @response = { code: 2303, message: 'Object does not exist' }
+    render(json: @response, status: :not_found)
+  end
+
+  def handle_parameter_missing(error)
+    @response = { code: 2003, message: error.message.gsub(/\n/, '. ') }
+    render(json: @response, status: :bad_request)
+  end
+
+  def handle_param_invalid(error)
+    @response = { code: 2005, message: error.message.gsub(/\n/, '. ') }
+    render(json: @response, status: :bad_request)
+  end
+
+  def handle_access_denied(error)
+    @response = { code: 2201, message: 'Authorization error' }
+    logger.error error.to_s
+    render(json: @response, status: :unauthorized)
+  end
+
+  def handle_throttle_error(error)
+    @response = { code: 2502, message: Shunter.default_error_message }
+    logger.error error.to_s unless Rails.env.test?
+    render(json: @response, status: :bad_request)
+  end
+
+  def create_repp_log
+    log_attributes = build_log_attributes
+    ApiLog::ReppLog.create(log_attributes)
+  end
+
+  def build_log_attributes
+    {
+      request_path: request.path, ip: request.ip,
+      request_method: request.request_method,
+      request_params: build_request_params_json,
+      uuid: request.try(:uuid),
+      response: @response.to_json,
+      response_code: response.status,
+      api_user_name: current_user.try(:username),
+      api_user_registrar: current_user.try(:registrar).try(:to_s)
+    }
+  end
+
+  def build_request_params_json
+    request.params.except('route_info').to_json
+  end
+
+  def logger
+    Rails.logger
+  end
+end
diff --git a/app/controllers/repp/v1/base_controller.rb b/app/controllers/repp/v1/base_controller.rb
index d2057599e..1faca4e68 100644
--- a/app/controllers/repp/v1/base_controller.rb
+++ b/app/controllers/repp/v1/base_controller.rb
@@ -3,51 +3,18 @@ module Repp
     class BaseController < ActionController::API # rubocop:disable Metrics/ClassLength
       attr_reader :current_user
 
-      around_action :log_request
+      include ErrorAndLogHandler
+
       before_action :authenticate_user
       before_action :set_locale
       before_action :validate_webclient_ca
-      before_action :validate_client_certs
-      before_action :check_ip_restriction
+      before_action :validate_api_user_cert
+      before_action :check_registrar_ip_restriction
+      before_action :check_api_ip_restriction
       before_action :set_paper_trail_whodunnit
 
       private
 
-      def log_request
-        yield
-      rescue ActiveRecord::RecordNotFound
-        @response = { code: 2303, message: 'Object does not exist' }
-        render(json: @response, status: :not_found)
-      rescue ActionController::ParameterMissing, Apipie::ParamMissing => e
-        @response = { code: 2003, message: e.message.gsub(/\n/, '. ') }
-        render(json: @response, status: :bad_request)
-      rescue Apipie::ParamInvalid => e
-        @response = { code: 2005, message: e.message.gsub(/\n/, '. ') }
-        render(json: @response, status: :bad_request)
-      rescue CanCan::AccessDenied => e
-        @response = { code: 2201, message: 'Authorization error' }
-        logger.error e.to_s
-        render(json: @response, status: :unauthorized)
-      rescue Shunter::ThrottleError => e
-        @response = { code: 2502, message: Shunter.default_error_message }
-        logger.error e.to_s unless Rails.env.test?
-        render(json: @response, status: :bad_request)
-      ensure
-        create_repp_log
-      end
-
-      # rubocop:disable Metrics/AbcSize
-      def create_repp_log
-        ApiLog::ReppLog.create(
-          request_path: request.path, request_method: request.request_method,
-          request_params: request.params.except('route_info').to_json, uuid: request.try(:uuid),
-          response: @response.to_json, response_code: response.status, ip: request.ip,
-          api_user_name: current_user.try(:username),
-          api_user_registrar: current_user.try(:registrar).try(:to_s)
-        )
-      end
-      # rubocop:enable Metrics/AbcSize
-
       def set_domain
         registrar = current_user.registrar
         @domain = Epp::Domain.find_by(registrar: registrar, name: params[:domain_id])
@@ -121,25 +88,23 @@ module Repp
         render(json: @response, status: :unauthorized)
       end
 
-      def check_ip_restriction
-        ip = webclient_request? ? request.headers['X-Client-IP'] : request.ip
-        return if registrar_ip_white?(ip) && webclient_request?
-        return if api_ip_white?(ip) && !webclient_request?
+      def check_api_ip_restriction
+        return if webclient_request?
+        return if @current_user.registrar.api_ip_white?(request.ip)
 
-        render_unauthorized_response(ip)
+        render_unauthorized_ip_response(request.ip)
       end
 
-      def registrar_ip_white?(ip)
-        return true unless ip
+      def check_registrar_ip_restriction
+        return unless webclient_request?
 
-        @current_user.registrar.registrar_ip_white?(ip)
+        ip = request.headers['Request-IP']
+        return if @current_user.registrar.registrar_ip_white?(ip)
+
+        render_unauthorized_ip_response(ip)
       end
 
-      def api_ip_white?(ip)
-        @current_user.registrar.api_ip_white?(ip)
-      end
-
-      def render_unauthorized_response(ip)
+      def render_unauthorized_ip_response(ip)
         @response = { code: 2202, message: I18n.t('registrar.authorization.ip_not_allowed', ip: ip) }
         render json: @response, status: :unauthorized
       end
@@ -167,18 +132,37 @@ module Repp
         render(json: @response, status: :unauthorized)
       end
 
-      def validate_client_certs
+      def validate_api_user_cert
         return if Rails.env.development? || Rails.env.test?
         return if webclient_request?
-        return if @current_user.pki_ok?(request.env['HTTP_SSL_CLIENT_CERT'],
-                                        request.env['HTTP_SSL_CLIENT_S_DN_CN'])
 
-        @response = { code: 2202, message: 'Invalid certificate' }
+        crt = request.env['HTTP_SSL_CLIENT_CERT']
+        com = request.env['HTTP_SSL_CLIENT_S_DN_CN']
+
+        return if @current_user.pki_ok?(crt, com)
+
+        render_invalid_cert_response
+      end
+
+      def validate_webclient_user_cert
+        return if skip_webclient_user_cert_validation?
+
+        crt = request.headers['User-Certificate']
+        com = request.headers['User-Certificate-CN']
+
+        return if @current_user.pki_ok?(crt, com, api: false)
+
+        render_invalid_cert_response
+      end
+
+      def render_invalid_cert_response
+        @response = { code: 2202, message: 'Invalid user certificate' }
         render(json: @response, status: :unauthorized)
       end
 
-      def logger
-        Rails.logger
+      def skip_webclient_user_cert_validation?
+        !webclient_request? || request.headers['Requester'] == 'tara' ||
+          Rails.env.development?
       end
 
       def auth_values_to_data(registrar:)
diff --git a/app/controllers/repp/v1/registrar/auth_controller.rb b/app/controllers/repp/v1/registrar/auth_controller.rb
index 5da1b3a38..676ea670e 100644
--- a/app/controllers/repp/v1/registrar/auth_controller.rb
+++ b/app/controllers/repp/v1/registrar/auth_controller.rb
@@ -2,9 +2,11 @@ module Repp
   module V1
     module Registrar
       class AuthController < BaseController
+        before_action :validate_webclient_user_cert, only: :index
         skip_before_action :authenticate_user, only: :tara_callback
-        skip_before_action :check_ip_restriction, only: :tara_callback
-        skip_before_action :validate_client_certs, only: :tara_callback
+        skip_before_action :check_registrar_ip_restriction, only: :tara_callback
+        skip_before_action :check_api_ip_restriction, only: :tara_callback
+        skip_before_action :validate_api_user_cert, only: :tara_callback
 
         THROTTLED_ACTIONS = %i[index tara_callback].freeze
         include Shunter::Integration::Throttle
@@ -21,7 +23,10 @@ module Repp
         def tara_callback
           user = ApiUser.from_omniauth(auth_params)
           response = { code: 401, message: I18n.t(:no_such_user), data: {} }
-          render(json: response, status: :unauthorized) and return unless user && user&.active
+          unless user&.active && webclient_request?
+            render(json: response, status: :unauthorized)
+            return
+          end
 
           token = Base64.urlsafe_encode64("#{user.username}:#{user.plain_text_password}")
           render_success(data: { token: token, username: user.username })
diff --git a/config/application.yml.sample b/config/application.yml.sample
index 2de9c29cb..0d2fd399c 100644
--- a/config/application.yml.sample
+++ b/config/application.yml.sample
@@ -187,6 +187,13 @@ default_response_timeout: '1'
 
 epp_sessions_per_registrar: '4'
 
+shunter_default_adapter: "Shunter::Adapters::Redis"
+shunter_enabled: "false"
+shunter_redis_host: "redis"
+shunter_redis_port: "6379"
+shunter_default_timespan: '60'
+shunter_default_threshold: '100'
+
 # Since the keys for staging are absent from the repo, we need to supply them separate for testing.
 test:
   payments_seb_bank_certificate: 'test/fixtures/files/seb_bank_cert.pem'
diff --git a/test/application_system_test_case.rb b/test/application_system_test_case.rb
index 726767390..63c91fcde 100644
--- a/test/application_system_test_case.rb
+++ b/test/application_system_test_case.rb
@@ -19,6 +19,7 @@ end
 class JavaScriptApplicationSystemTestCase < ApplicationSystemTestCase
   self.use_transactional_tests = false
   DatabaseCleaner.strategy = :truncation
+  Webdrivers::Chromedriver.required_version = '114.0.5735.90'
 
   Capybara.register_driver(:chrome) do |app|
     options = ::Selenium::WebDriver::Chrome::Options.new
diff --git a/test/integration/repp/v1/accounts/switch_user_test.rb b/test/integration/repp/v1/accounts/switch_user_test.rb
index 2299f2bf5..fa26b442d 100644
--- a/test/integration/repp/v1/accounts/switch_user_test.rb
+++ b/test/integration/repp/v1/accounts/switch_user_test.rb
@@ -53,8 +53,8 @@ class ReppV1AccountsSwitchUserTest < ActionDispatch::IntegrationTest
   end
 
   def test_returns_error_response_if_throttled
-    ENV["shunter_default_threshold"] = '1'
-    ENV["shunter_enabled"] = 'true'
+    ENV['shunter_default_threshold'] = '1'
+    ENV['shunter_enabled'] = 'true'
 
     new_user = users(:api_goodnames)
     new_user.update(identity_code: '1234')
@@ -71,7 +71,7 @@ class ReppV1AccountsSwitchUserTest < ActionDispatch::IntegrationTest
     assert_response :bad_request
     assert_equal json[:code], 2502
     assert response.body.include?(Shunter.default_error_message)
-    ENV["shunter_default_threshold"] = '10000'
-    ENV["shunter_enabled"] = 'false'
+    ENV['shunter_default_threshold'] = '10000'
+    ENV['shunter_enabled'] = 'false'
   end
 end
diff --git a/test/integration/repp/v1/base_test.rb b/test/integration/repp/v1/base_test.rb
index ed69eba13..3fdc84c30 100644
--- a/test/integration/repp/v1/base_test.rb
+++ b/test/integration/repp/v1/base_test.rb
@@ -43,7 +43,7 @@ class ReppV1BaseTest < ActionDispatch::IntegrationTest
     assert_equal 'Invalid authorization information', response_json[:message]
   end
 
-  def test_takes_ip_whitelist_into_account
+  def test_takes_ip_whitelist_into_account_if_api_request
     Setting.api_ip_whitelist_enabled = true
     Setting.registrar_ip_whitelist_enabled = true
 
@@ -67,7 +67,7 @@ class ReppV1BaseTest < ActionDispatch::IntegrationTest
 
     Repp::V1::BaseController.stub_any_instance(:webclient_request?, true) do
       Repp::V1::BaseController.stub_any_instance(:validate_webclient_ca, true) do
-        get repp_v1_contacts_path, headers: @auth_headers.merge!({ 'X-Client-IP' => whiteip.ipv4 })
+        get repp_v1_contacts_path, headers: @auth_headers.merge!({ 'Request-IP' => whiteip.ipv4 })
       end
     end
 
@@ -77,6 +77,43 @@ class ReppV1BaseTest < ActionDispatch::IntegrationTest
     Setting.registrar_ip_whitelist_enabled = false
   end
 
+  def test_validates_webclient_user_certificate_ok
+    cert = certificates(:registrar)
+    @auth_headers.merge!({ 'User-Certificate' => cert.crt, 'User-Certificate-CN' => cert.common_name })
+
+    Repp::V1::BaseController.stub_any_instance(:webclient_request?, true) do
+      Repp::V1::BaseController.stub_any_instance(:validate_webclient_ca, true) do
+        get repp_v1_registrar_auth_index_path, headers: @auth_headers
+      end
+    end
+
+    assert_response :ok
+  end
+
+  def test_validates_webclient_user_certificate_if_missing
+    Repp::V1::BaseController.stub_any_instance(:webclient_request?, true) do
+      Repp::V1::BaseController.stub_any_instance(:validate_webclient_ca, true) do
+        get repp_v1_registrar_auth_index_path, headers: @auth_headers
+      end
+    end
+
+    assert_unauthorized_user_cert
+  end
+
+  def test_validates_webclient_user_certificate_if_revoked
+    cert = certificates(:registrar)
+    cert.update(revoked: true)
+    @auth_headers.merge!({ 'User-Certificate' => cert.crt, 'User-Certificate-CN' => cert.common_name })
+
+    Repp::V1::BaseController.stub_any_instance(:webclient_request?, true) do
+      Repp::V1::BaseController.stub_any_instance(:validate_webclient_ca, true) do
+        get repp_v1_registrar_auth_index_path, headers: @auth_headers
+      end
+    end
+
+    assert_unauthorized_user_cert
+  end
+
   private
 
   def assert_unauthorized_ip
@@ -86,4 +123,12 @@ class ReppV1BaseTest < ActionDispatch::IntegrationTest
     assert_equal 2202, response_json[:code]
     assert response_json[:message].include? 'Access denied from IP'
   end
+
+  def assert_unauthorized_user_cert
+    response_json = JSON.parse(response.body, symbolize_names: true)
+
+    assert_response :unauthorized
+    assert_equal 2202, response_json[:code]
+    assert response_json[:message].include? 'Invalid user certificate'
+  end
 end
diff --git a/test/integration/repp/v1/registrar/auth/tara_callback_test.rb b/test/integration/repp/v1/registrar/auth/tara_callback_test.rb
index 918fce9cc..0493f47f4 100644
--- a/test/integration/repp/v1/registrar/auth/tara_callback_test.rb
+++ b/test/integration/repp/v1/registrar/auth/tara_callback_test.rb
@@ -18,7 +18,12 @@ class ReppV1RegistrarAuthTaraCallbackTest < ActionDispatch::IntegrationTest
       },
     }
 
-    post '/repp/v1/registrar/auth/tara_callback', headers: @auth_headers, params: request_body
+    Repp::V1::BaseController.stub_any_instance(:webclient_request?, true) do
+      Repp::V1::BaseController.stub_any_instance(:validate_webclient_ca, true) do
+        post '/repp/v1/registrar/auth/tara_callback', headers: @auth_headers, params: request_body
+      end
+    end
+
     json = JSON.parse(response.body, symbolize_names: true)
 
     assert_response :ok
@@ -43,4 +48,21 @@ class ReppV1RegistrarAuthTaraCallbackTest < ActionDispatch::IntegrationTest
     assert_response :unauthorized
     assert_equal 'No such user', json[:message]
   end
+
+  def test_invalidates_user_if_not_webclient_request
+    request_body = {
+      auth: {
+        uid: 'EE1234',
+      },
+    }
+
+    Repp::V1::BaseController.stub_any_instance(:webclient_request?, false) do
+      post '/repp/v1/registrar/auth/tara_callback', headers: @auth_headers, params: request_body
+    end
+
+    json = JSON.parse(response.body, symbolize_names: true)
+
+    assert_response :unauthorized
+    assert_equal 'No such user', json[:message]
+  end
 end