Hello,
I'm using Cygwin's Xwindows. When I launch applications that connect to the windowing system, the Kerio Personal Firewall 2.1.5 catches it. I launched a few Xwindows applications to characterize the accesses:
Local Remote ------------- :1120 127.0.0.1:1034 :1122 127.0.0.1:1034 :1123 127.0.0.1:1023 :1124 127.0.0.1:1034 :1125 127.0.0.1:1125
Both TCP and UDP (outgoing) is required for most of the applications tried. I created a single rule for any application and any port to allow access for the plurality of applications:
Local_Loopback_for_Xwin ----------------------- * Protocol: TCP and UDP * Direction: Outgoing * Local endpoint: Any port, any application - Different applications use different ports e.g. 1120, 1122, 1123, 1124, 1125 * Remote endpoint: 127.0.0.1, any port - Different applications use different ports e.g. 1034, 1034, 1023, 1034, 1125 * Always permit
Since it's a local connection, is it safe to have an open-ended port specification and open-ended application specification?
The safer alternative is to specify exactly which application the rule applies to, which is less convenient. I'd need a rule for each application. Also, if some Xwindows activity or application doesn't work in the future, it might take some troubleshooting before tracking it back to the firewall.
Hopefully, the open-endedness in the rule specification sacrifices very little safety, since it's much more convenient.