Proxying on an HTTP backend and sending back 50x errors 20% of the time:

$ vaurien --protocol http --proxy --backend \
          --behavior 20:error

An SSL SMTP proxy with a 5% error rate and 10% delays:

$ vaurien --proxy --backend \
          --protocol smtp --behavior 5:error,10:delay

An SSL SMTP Proxy that starts to error out after 12 calls (so in the middle of the transaction):

$ vaurien --proxy --backend \
          --protocol smtp --behavior 100:error --behavior-error-warmup 12

Adding a 1 second delay on every call to a MySQL server:

$ vaurien --proxy --backend --stay-connected --behavior 100:delay \
          --behavior-delay-sleep 1

A quick’n’dirty SSH tunnel from your box to another box:

$ vaurien --stay-connected --proxy --backend \