It is possible to do this. Take a look at:
http://devcentral.f5.com/wiki/default.aspx/iRules/LTMMaintenancePage.html
...for an example. This particular iRule serves content directly from the LTM (in this case, a maintenance page) and shows how/where to put the text and uuencoded graphics.
Hmm, but can I do it with just iRule, as this http in one line and non easy editable is too complicated, actually the wpad.dat file is very simple javascript code like this:
function FindProxyForURL(url, host) {
if(shExpMatch(host, "*[^0123456789.]*") == false)
if( isInNet(host, "127.0.0.0", "255.0.0.0")
|| isInNet(host, "172.17.0.0", "255.255.0.0")
|| isInNet(host, "172.18.0.0", "255.255.0.0")
)
return "DIRECT";
else
return "PROXY proxygateway.internal:8080; DIRECT";
)
I found one one similar example -
http://devcentral.f5.com/Wiki/default.aspx/iRules/LTMMaintenancePageLite.html but didn't figure how how to access access it from F5 with url like this -
http://wpad.internal/wpad.dat