This is a short one. Really short. ISA tricked me. Once more.
I have a setup with ISA Server 2006 where only certain people have access to outside FTP services. So I’ve setup a rule to just allow FTP for only these few users to the external network. A few days later people started complaining that connecting to FTP servers would succeed, reading files also but changing files on the servers always resulted in an “Access Denied” or “550″ message. Hum - that is strange.
After using the live monitoring feature of ISA and trying it myself over and over again (that actually took me two hours), I tried to see whether the “community” did encounter this before - and see, the solution is as easy as stupid:
Right-Click the FTP access rule, choose “Configure FTP” (Configure FTP! Believe it? How can anyone be *that* blind?) and untick the “Read-Only” box.