a good > reason to be let in. In practice, you need to let a few ICMP messages through, then. For example, source quench and destination unreachable. -- [ 7'ism - a condition by which the sufferer experiences an inability to give concise answers,...

blocked by my firewall. The firewall reports > follow the pattern below:- >> ICMP packet dropped - Source:a.b.c.d, 3, WAN - Destination:w.x.y.z, > 1, LAN - >> The firewall drops them as 'Destination Unreachable' since port 1 > doesn't exist...

sygate and shields up. Archived from groups: comp.security.firewalls () When I test my sygate firewall on Gibson's Shields Up. The ports are coming up as closed, but not all are coming up as what GRC calls stealth. I figure this is to be expected. I...

3: Destination Unreachable Packets Network troubleshooters – Often closely track ICMP Destination Unreachable packets Host that sends Destination Unreachable packet – Must return IP header and eight bytes of original datagram that triggered this response...

will see that. Your "Personal Firewall" just violates the Internet Protocol by nor sending RST (see RFC 793 / STD 0007, section 3.4), nor sending ICMP Destination Unreachable Message with code 3 (port unreachable, see RFC 792 / STD 0005). Say: your...

I'm under the impression that one should allow ICMP type 3 both in and out > thru the firewall. I'm using Kerio here, so I set up a rule to allow type > 3 incoming and outgoing to any address. I prefer allowing "Destination Unreachable", so long as it...

Destination: 255.255.255.255 (255.255.255.255) User Datagram Protocol, Src Port: bootpc (68), Dst Port: bootps (67) Source port: bootpc (68) Destination port: bootps (67) Length: 556 Checksum: 0x6fcc (correct) Bootstrap Protocol Message...

because an host seems to be not there only, if a router before the host sends ICMP Destination Unreachable with code 0 (net unreachable) or code 1 (host unreachable), see RFC 791 / STD 0005, Therefore i.e. portscanners have no problem to detect a PC,...

ICMP. Sure could use some help. Which of the following should be: (1) allowed incoming (2) allowed outgoing (3) allowed both incoming and outgoing. ICMP 0 echo reply ICMP 8 echo request ICMP 3 destination unreachable ICMP 10 router solicitation...

you're getting a packet back! Why? The router before the non-existing PC then is sending an ICMP packet, either which means "no computer here", or which means "the complete network is not here, so there cannot be a computer" (ICMP destination unreachable...