Management is asking me to tweak a couple of sites (http only is OK, https not needed) that employees access from our internal network. It would be something very basic, inserting some JS that displays a message. This would only be needed for some particular sites.
I was wondering what tool would you recommend for this? UNIX/Debian based.
Squid and perl :)
Squid can send whatever it serves back through a content filter, so you can do whatever you want.