I followed the steps strictly from the official documents here :http://trafficserver.readthedocs.org/en/latest/admin/transparent-proxy/bridge.en.html#inline-on-a-linux-bridge
then the Linux bridge works well, every app on the client PC can access the internet but the browser visiting http websites always gets timeout(https is ok).
the 3 processes traffic_cop, traffic_manager and traffic_server can be seen using "ps aux".
there is no access log file squid.log in the log path.
and the Wireshark on the PC using as bridge can not find any interfaces in this situation.
