host={HostList} -- interface host with the client.
true if the client has connected to the DeleGate via the specified network
interface included in the HostList.
Note that this option is applicable to any client side protocol, that is,
not only HTTP-DeleGate but also DeleGate for FTP, POP, NNTP, etc. can
switch destination server based on the client side interface if
its has an IP address distinguishable from others.
When the DeleGate is acting as an origin HTTP server and a virtual
host name is shown in "Host: host" field in the request message,
the virtual name is examined prior to the real host name. If
multiple virtual names are bound to the same IP-address,
prefix "-" to the virtual hostname like "host=-hostname" to
distinguish among virtual names.