ping which port? Solved

Question

Good evening,  I would like to have some information.  What is the (incoming) port of a computer that receives a ping from another computer, is it a random port or a fixed port?

Géca · Accepted Answer

Good evening,

The ping uses the ICMP protocol (the same level as TCP). The concept of port comes into play at a higher level (TCP or UDP protocol).

http://www.commentcamarche.net/internet/icmp.php3

Happy reading.

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sebsauvage · Answer

He is right.  PING uses neither TCP nor UDP and therefore has no concept of port.

michel · Answer

Thank you,  Even though I find it a bit hard to understand...  Why on this page, "recipient message not accessible," is code 3 = port not accessible?  http://abcdrfc.free.fr/rfc-vf/rfc792.html#2

sebsauvage · Answer

There is a very interesting diagram that places most protocols in the different OSI layers: http://sebsauvage.net/comprendre/tcpip/protocols.pdf  ICMP is right next to IP, in the same layer.

sebsauvage · Answer

ZA blocks ping (as well as everything else) by default.  Can this be configured differently than through a firewall?  Under Windows, to my knowledge, it is not possible without a firewall.

michel · Answer

I don’t know why, my firewall is set to maximum, and during tests, for example with Shields Up:

http://assiste.free.fr/p/scan_de_ports_gratuits_en_ligne/scan_de_ports_en_ligne.php

It indicates that my PC is responding to the request, so it is not completely secure.

sebsauvage · Answer

Weird.  Check that you have the very latest version (I have 5.5.094.000)

michel · Answer

Well, I don't understand anymore.

I had the latest version of ZA (5.5.109.000), so I uninstalled it and then reinstalled it, still getting responses to the echo...

So to be sure, I installed another firewall, Look 'n' Stop, and there too responses to ping echo requests.

????????

So it wouldn't come from my firewall, but from what then?

It's certainly not very important since my computer is relatively well protected, but I admit that I would like to know why these tests show a weakness in my protection.

sebsauvage · Answer

When you ping, are you pinging from the local network or from a machine on the internet?  Because ZA (and other firewalls) accept to respond to the ping when it comes from a local IP.

michel · Answer

When you ping, do you ping from the local network or from a machine on the internet?  If I understood your question correctly, when I ping, I do it from a machine on the internet, since I am not on a network, and when I do this, ZA asks me to allow the request.  So for me, the reliability of the GRC test and others remains, during which there was no solicitation from my firewall, not the slightest sign...  Here is the report it indicates to me:  GRC Port Authority Report created on UTC: 2005-08-03 at 08:23:28 Results from scan of ports: 0, 21-23, 25, 79, 80, 110, 113, 119, 135, 139, 143, 389, 443, 445, 1002, 1024-1030, 1720, 5000 0 Ports Open 0 Ports Closed 26 Ports Stealth --------------------- 26 Ports Tested ALL PORTS tested were found to be: STEALTH. TruStealth: FAILED - ALL tested ports were STEALTH, - NO unsolicited packets were received, - A PING REPLY (ICMP Echo) WAS RECEIVED.

sebsauvage · Answer

GRC Port Authority Report created on UTC: 2005-08-03 at 08:23:28 Results from scan of ports: 0, 21-23, 25, 79, 80, 110, 113, 119, 135, 139, 143, 389, 443, 445, 1002, 1024-1030, 1720, 5000 0 Ports Open 0 Ports Closed 26 Ports Stealth

Ben, the report is perfect!

No open ports.

michel · Answer

Yes, I know that all my ports are invisible.

But it's this line that indicates to me that the report is not perfect.

- A PING REPLY (ICMP Echo) WAS RECEIVED.

Finally, thank you for taking an interest in my topic, it's nice of you.

sebsauvage · Answer

Oh sorry, I read too quickly.

It should be in the ZA options, I think.
I don’t have ZA at hand;
Go check in the Firewall tab, "Advanced" button
(I believe there are additional options).

For your information, I have ZA and I tested it on grc.com:
I am totally stealth, including on ping.

So it must just be a settings issue.

michel · Answer

In the advanced options of ZA, there are:

Block safe zone servers

--> checked

Block internet zone servers

--> checked

Allow non-standard protocols at high security level

--> unchecked

Allow outgoing DNS/DHCP connections in the safe zone with elevated settings

--> unchecked

Allow outgoing DNS/DHCP connections in the internet zone with elevated settings

--> unchecked

Lock the host file

--> checked (I don't know what this is for, so I checked it)

So apparently everything is set to maximum.

sebsauvage · Answer

weird :-.

michel · Answer

Finally!!!

I found where it was coming from, I really hadn't thought about it (I am stupid).

Being with Wanadoo, I had forgotten the integrated firewall of the Livebox, and yes, the error came from there...

By the way, I tested it by disabling it, and many ports appeared as visible, so you should never disable this pseudo firewall.

So many hours spent looking, when it was just under my eyes :-(((

So I configured it like this:

Receiving interface: ppp0 Transmitting interface: ppp0 Sequence: 0 Source IP from: 1.1.1.1 To: 254.254.254.254 Destination IP: 1.1.1.1 To: 254.254.254.254 Protocol: icmp

Is it correct?
Given that I have limited knowledge in this area, I would like an experienced opinion.

And here is the result with GRC:

GRC Port Authority Report created on UTC: 2005-08-03 at 13:49:11 Results from scan of ports: 0, 21-23, 25, 79, 80, 110, 113, 119, 135, 139, 143, 389, 443, 445, 1002, 1024-1030, 1720, 5000 0 Open Ports 0 Closed Ports 26 Stealth Ports --------------------- 26 Ports Tested ALL PORTS tested were found to be: STEALTH. TruStealth: PASSED - ALL tested ports were STEALTH, - NO unsolicited packets were received, - NO Ping reply (ICMP Echo) was received.

Phew!!!
Finally with Wanadoo, they could at least have put this in the default settings....

Thank you very much, sebsauvage, once again thanks to you, one more problem solved.

Conrad · Answer

Hello everyone,

I'm using VNC for remote assistance; the person gives me their IP number, I connect and everything works fine.
But as soon as I try to ping with that same IP number, I can't find it. Why ??
VNC is configured on ports 5800 and 5900.

I'm connected via Wi-Fi to a modem/router, I tried doing the same thing with Ethernet and got the same result. Do I need to manage a NAPT rule?

Thanks to the experts for your response.

Ping which port?

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