How can I provide yahoo-mail only (block other sites) to a PC ?

Question

How can I provide yahoo-mail only (block other sites) to a PC ?

Answer 1

One way would be to block the DNS ports with IPSec (thereby breaking host name resolution) and add yahoo's mail page host name to the HOSTS file, but this assumes that mail page only uses one host name.  Also, if yahoo changes the IP address[es] associated with that host name, the scheme will break and you will have to alter the HOSTS file by hand to fix it.

DNS uses port 53 (both UDP and TCP).  IPSec configuration is a quagmire, get to it using the Local Security Policy console in administrative tools, add rules that deny traffic between any source and destination IP addresses, from any source port to destination port 53.  (One each for TCP and UDP.)

The HOSTS file is in %windir%\system32\drivers\etc, it's format is described in a comment block inside the file, it's just plain text, you can edit it with notepad.

I don't use yahoo mail so you're on your own figuring out the host name[s] it uses; you can use NSLOOKUP.EXE to resolve the IP address[es] -- before enabling the IPSec rules, of course.  :-)

Good Luck!