When I first got the Windows message "Scanner unreachable", I tried unplugging the power cord and plugging it back in, but the scanner was still 'unreachable'. I also tried unplugging the USB cable and plugging it back in, but still no scanner. I also tried plugging the USB cable into another USB port on my PC, but no scanner.
C:\corenetworkz>ping 4.2.2.2 Pinging 4.2.2.2 with 32 bytes of data: Destination host unreachable. Destination host unreachable. Destination host unreachable. Destination host unreachable. Ping statistics for 4.2.2.2: Packets: Sent = 4, Received = 0, Lost = 4 (100% loss), C:\corenetworkz> Why Am I Getting Destination Host Unreachable ICMP Error [modauthkerb] Intermittent ICMP 'port unreachable' from The problem I'm having is that the apache server (RHEL5 VM) sends back an 'ICMP port unreachable' message to the KDC every 20-50 packets. I patched mod_auth_kerb with the passwd-cache-patch, which reduced the apache <-> KDC traffic down to almost nothing, and I … ICMP Unreachable - Engineer Life Nov 09, 2016 networking - Is ICMP port unreachable error generated by ICMP Port unreachable is a code 3 within type 3 3.3. Port Unreachable - generated if the designated transport protocol (e.g., UDP) is unable to demultiplex the datagram in the transport layer of the final destination but has no protocol mechanism to inform the sender
R3 will reply with a type 3 destination unreachable message. Take a close look at the type and code. The type tells us the destination is unreachable. This could mean that the remote host or network is unreachable. However, the code is number 3 which means port unreachable. R3 uses this code because nothing is listening on UDP port 33435.
Barring server S doing something (like sending an ICMP Destination Port Unreachable) or the application on C stopping this transfer for some reason, it will continue to send 3 TB of data to S. S must still receive (and then discard) all this data. The ICMP Destination Port Unreachable prevents the majority of this data from ever being sent. A Destination Unreachable message that is received MUST be reported to the transport layer. A transport protocol that has its own mechanism for notifying the sender that a port is unreachable (e.g., TCP, which sends RST segments) MUST nevertheless accept an ICMP Port Unreachable for the same purpose. A port unreachable message indicates that the process or application the source host is attempting to establish a connection with is not active on the destination host. Typically this type of message is sent when an application has not been started or has failed on this host. "ICMP port unreachable" messages here indicate something very fishy (or broken). An "ICMP port unreachable" message should only be received if you are attempting to access an unavailable TCP or UDP service, not in response to an ICMP echo request (unless I missed the fine print in an RFC somewhere).
server unreachable - Xfinity Help and Support Forums - 3347331
If you do not specify which ICMP message to reject with, the server by default will send back ICMP port unreachable (type 3, code 3).--reject-with modifies this behaviour to send a specific ICMP message back to the source host. You can find information about --reject-with and the available rejection messages in man iptables: REJECT Protocol Unreachable. The protocol specified in the Protocol field was invalid for the host to which the datagram was delivered. 3. Port Unreachable. The destination port specified in the UDP or TCP header was invalid. 4. Fragmentation Needed and DF Set. This is one of those “esoteric” codes. whereas with a running service, the service was correctly listening on port 161: # /etc/init.d/snmpd start # netstat -apn|grep snmpd udp 0 0 0.0.0.0:161 0.0.0.0:* 21018/snmpd and also responding with 3424 lines of SNMP counters to the # snmpwalk localhost -c public -v1. Please understand that this we cannot try debugging the issue any deeper in Nov 09, 2016 · And R2 will send destination host unreachable message back to HOST1. Code 2 : Protocol unreachable & Code 3 : Port unreachable Normaly you get this message from destination host to tell you that protocol module or desination port not known by destination host. Example User on HOST2 telnet to WEB SERVER. When packet arrvice WEB SERVER, it de UDP scan works by sending a UDP packet to every targeted port. For most ports, this packet will be empty (no payload), but for a few of the more common ports a protocol-specific payload will be sent. Based on the response, or lack thereof, the port is assigned to one of four states, as shown in Table 5.3 . The problems appears when I try to make the call from the BPL modems. If I capture the packets between them, I can see all the time the same pattern. After the SIP packets, which seems to be ok, the modem starts to send one UDP packet to the X-lite phone, and receive an ICMP packet with the "port unreachable" message.