diff --git a/.env.sample b/.env.sample
index b4826ee..a7b1ec2 100644
--- a/.env.sample
+++ b/.env.sample
@@ -2,6 +2,7 @@
 NODE_ENV="development"
 
 # general
+TRUST_PROXY="loopback" # empty to disable, ('loopback', 'linklocal', 'uniquelocal' or ip addresses)
 ENABLED_PROTOCOLS="http,https" # ('http', 'https')
 ENABLED_REDIRECT_HTTP_HTTPS="no" # redirect http to https ('yes' or 'no')
 INDEX_REDIRECT_TYPE="permanent" # ('temporary' or 'permanent')