diff --git a/nginx.env.conf b/nginx.env.conf
index 2d7f26c..8226671 100644
--- a/nginx.env.conf
+++ b/nginx.env.conf
@@ -162,6 +162,7 @@ http {
           }),
           headers = {
             ["Content-Type"] = "application/x-www-form-urlencoded",
+            ["Host"] = ngx.var.host
           },
           method = "POST",
           ssl_verify = false
@@ -182,7 +183,8 @@ http {
             clientId = client_id
           },
           headers = {
-            ["Authorization"] = "Bearer " .. access_token
+            ["Authorization"] = "Bearer " .. access_token,
+            ["Host"] = ngx.var.host
           },
           method = "GET",
           ssl_verify = false
@@ -208,7 +210,8 @@ http {
         res, err = httpc:request_uri("http://${SSO_SERVICE_HOSTNAME}/auth/admin/realms/"..realm.."/clients/" .. client_id_rhssoid .. "/certificates/jwt.credential", {
           method = "GET",
           headers = {
-            ["Authorization"] = "Bearer " .. access_token
+            ["Authorization"] = "Bearer " .. access_token,
+            ["Host"] = ngx.var.host
           },
           ssl_verify = false
         })
@@ -251,7 +254,8 @@ http {
           body = body,
           headers = {
             ["Authorization"] = "Bearer " .. access_token,
-            ["Content-Type"] = content_type
+            ["Content-Type"] = content_type,
+            ["Host"] = ngx.var.host
           },
           ssl_verify = false
         })
@@ -274,21 +278,95 @@ http {
     location ~ ^/auth/realms/(${SSO_REALMS})/protocol/openid-connect/token$ {
       access_by_lua_block {
         ngx.log(ngx.INFO, "VERIFY: ", ngx.var.ssl_client_verify)
-        if ngx.var.ssl_client_verify ~= "SUCCESS" then
+        if ngx.var.ssl_client_verify ~= "SUCCESS" or not ngx.var.ssl_client_raw_cert then
           ngx.status = ngx.HTTP_FORBIDDEN
           ngx.header['Content-Type'] = 'application/json'
           ngx.say('{"error":"invalid_request","error_description":"You need to authenticate using an SSL/TLS Client Certificate."}')
           ngx.exit(ngx.HTTP_OK)
         end
-        ngx.log(ngx.ERR, "Authenticated Client : ", ngx.var.ssl_client_s_dn)
+        ngx.log(ngx.INFO, "Authenticated Client : ", ngx.var.ssl_client_s_dn)
       }
 
-      # Beware: no slash at the end of the proxy_pass directive since we don't want to rewrite URLs
-      proxy_pass http://${SSO_SERVICE_HOSTNAME};
-      proxy_set_header Host $host;
-      proxy_set_header X-Real-IP $remote_addr;
-      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
-      proxy_set_header X-Forwarded-Proto $scheme;
+      content_by_lua_block {
+        local jwt = require "resty.jwt"
+        local http = require "resty.http"
+
+        ngx.req.read_body()
+        local form, err = ngx.req.get_post_args()
+        if not form then
+          ngx.status = ngx.HTTP_BAD_REQUEST
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"You need to pass the token request arguments in the post body."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        local client_assertion = form['client_assertion']
+        local client_assertion_type = form['client_assertion_type']
+        if not client_assertion_type or client_assertion_type ~= "urn:ietf:params:oauth:client-assertion-type:jwt-bearer" then
+          ngx.status = ngx.HTTP_BAD_REQUEST
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"Only JWT is allowed for client authentication. See RFC 7523."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        if not client_assertion then
+          ngx.status = ngx.HTTP_BAD_REQUEST
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"No client_assertion found."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        local certificate = ngx.var.ssl_client_raw_cert
+        local jwt_obj = jwt:load_jwt(client_assertion)
+        if not jwt_obj.valid then
+          ngx.status = ngx.HTTP_BAD_REQUEST
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"client_assertion is not a valid JWT."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        if jwt_obj.header.alg ~= "RS256" then
+          ngx.status = ngx.HTTP_BAD_REQUEST
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"client_assertion must be signed using the RS256 algorithm."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        jwt_obj = jwt:verify_jwt_obj(certificate, jwt_obj, {})
+        if not jwt_obj.verified then
+          ngx.status = ngx.HTTP_FORBIDDEN
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"invalid_request","error_description":"client_assertion signature cannot be verified."}')
+          ngx.log(ngx.WARN, "JWT validation error: ", jwt_obj.reason)
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        local httpc = http.new()
+
+        local body = ngx.req.get_body_data()
+        local headers = {}
+        local h = ngx.req.get_headers()
+        for k, v in pairs(h) do
+          headers[k] = v
+        end
+        local res, err = httpc:request_uri("http://${SSO_SERVICE_HOSTNAME}" .. ngx.var.uri, {
+          body = body,
+          headers = headers,
+          method = "POST",
+          ssl_verify = false
+        })
+
+        if not res then
+          ngx.status = ngx.HTTP_INTERNAL_SERVER_ERROR
+          ngx.header['Content-Type'] = 'application/json'
+          ngx.say('{"error":"server_error","error_description":"Could not get a response from RH-SSO."}')
+          ngx.exit(ngx.HTTP_OK)
+        end
+
+        ngx.status = res.status;
+        ngx.header['Content-Type'] = res.headers['Content-Type']
+        ngx.say(res.body);
+      }
     }
 
     location ~ ^/.* {
diff --git a/tests/sign.sh b/tests/sign.sh
new file mode 100755
index 0000000..367a05c
--- /dev/null
+++ b/tests/sign.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+
+if [ "$#" -ne 2 ]; then
+    echo "Usage: $0 subject audience"
+    exit 1
+fi
+
+ISSUER="$1"
+SUBJECT="$1"
+AUDIENCE="$2"
+EXPIRATION=$(date -v+1d "+%s")
+ISSUED_AT=$(date "+%s")
+NOT_BEFORE=$(date -v-1H "+%s")
+TOKENID=$(openssl rand -hex 8)
+
+jwt -claim "iss=$ISSUER" \
+    -claim "sub=$SUBJECT" \
+    -claim "aud=$AUDIENCE" \
+    -claim "exp=$EXPIRATION" \
+    -claim "iat=$ISSUED_AT" \
+    -claim "nbf=$NOT_BEFORE" \
+    -claim "jti=$TOKENID" \
+    -sign + \
+    -key "client.key" \
+    -alg "RS256"
+
+
+