Hopefully I've chosen the correct forum for this...
I have two MBPs, and two iphones in the house, connecting wirelessly through an AirportExtreme.
Out of all the devices, there is one MBP that can't be pinged even though it's online and works perfectly. It can see everything else, but nothing can ping it. Since noone can ping it (by IP), obviously it isn't DNS or other routing.
I've got the firewall turned off on all machines since I'm on a private network, so that isn't it either.
First, the firewall wasn't on, so I don't think the Stealth Mode was a factor but I did try turning the f/w on so that I could deselect that option. No change.
Also, it's not really a service that I want to allow access to, so I haven't enabled any of the services. I have an http server running on 8080 that I want the other machines to access (but as I previously mentioned I can't even ping it).
I'm pretty sure that it isn't just pings that aren't getting through though since I can't ssh into it from the other MBP either, even though remote login is enabled.
Since you are pinging by numeric IP address, maybe try changing its LAN IPA to manual address with DHCP and give it an address within the subnet but outside the DHCP pool.
And for lack of any better ideas, are you sure you are pinging the right IPA? I know, I know, it sounds insultingly stupid for me to even suggest this, but I suggest it coz' it almost sounds like you're not calling the correct address.
One last thing as a random troubleshooting tip: On the machine to which you are trying to connect, launch Terminal.app as an admin user and try running sudo tcpdump -i en1 dst host 192.168.x.x, where en1 is the airport card interface (use en0 if tethered via ethernet cable) and 192.168.x.x is the IPA of the destination machine. At least you'll be able to see if the computer is even seeing the incoming packets. Where to go from there I'm really not sure....
Outside of that, I'm pretty much out of ideas, good ones and bad ones.
Excellent idea re: the tcpdump - I hadn't thought of that.
Don't worry about being insulting. I do enough phone support to know that the obvious questions are not always obvious to the other person. Although if I never show my face around here again you'll know why 🙂
I'll update the thread after I debug a little more.
I was thinking that if you could repeat this exercise, that maybe there might be a log file in /private/var/log/, like /private/var/log/secure.log or /private/var/log/system.log, that might tell you something a little more revealing. But I can't identify a viable candidate log file. I did a successful ping from one machine to the other and checked the two log files mentioned above on the target machine and saw no activity related to the incoming pings or to the outgoing responses in them. Just seems like there would be a log of that somewhere -- everything else under the sun gets logged somewhere. Assuming that such a log file exists, hopefully you or someone else following this thread can identify it.
Dwayne K King wrote:
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
Request timeout for icmp_seq 2
Did you or anyone else turn off ICMP on that machine? If ICMP is off, you can't be pinged. It's a 'security' option sometimes used to prevent certain kinds of attack, such as the Ping of Death. Some websites (www.microsoft.com is an example) have ICMP turned of for precisely that reason and cannot be pinged, and if you try, you get
exactly the 'request timeout' message above.
And, no, I have no idea how you'd do that without involving the firewall at some point. Are you
sure that the firewall is disabled on that machine, 'cause it sure looks as though it's live and is blocking ICMP.
