SQUID as Tranparent Proxy

[Roman Gelfand <rgelfand2@xxxxxxxxx>]

When squid is acting as transparent proxy, does squid rewrite ip or
layer 2 data.

Let's say the route is as follows.  Will the outgoing traffic be seen
as coming from client's ip as source ip or squid's ip as source ip?

client ====> firewall ====>  wan
                     ^      ||
                     ||      ||
              eth0||      || GRE tunnel (on eth0 Physical interface)
                     ||      ||
                     ||      V
                  SQUID Server

Thanks in advance