Can't access SSH server when it's on a wireless laptop.

jschiwal · 04-18-2011, 07:49 AM

I wonder if the problem is with a spotty wifi connection. Once an ssh connection is made, does it drop off?

anomie · 04-18-2011, 07:59 AM

Quote:

Originally Posted by RaisedByWolves

Code:

PC>arp -a
Interface: 192.168.1.115 --- 0x2
  Internet Address      Physical Address      Type
  192.168.1.1           98-fc-11-81-1d-c5     dynamic
  192.168.1.117         00-00-00-00-00-00     invalid
...

Something strange is happening with the PC's ARP cache. Next time the laptop hops from Ethernet to wifi, issue the command (from the laptop):

Code:

# arping -U -c 2 192.168.1.117

Everything work OK afterward?

RaisedByWolves · 04-19-2011, 09:54 PM

Last night I tested to see how long a connection would last (once they find each other). I was able to stay SSH'ed in for six hours or so before I went to bed. I have been knocked off the SSH connection in the past but I wouldn't characterize the connection as tenuous once made.

running arping on the laptop didn't make the PC aware of it. They still can't see each other until they are both pinging each other.

I did have to use a lowercase 'u' instead of a capital 'U' for arping

results:

(117 is laptop, 116 is pc)

Code:

# arping -u -c 2 192.168.1.117
arping: Um.. lo looks like the wrong interface to use. Is it? (-i switch)
arping: using it anyway this time
ARPING 192.168.1.117

--- 192.168.1.117 statistics ---
2 packets transmitted, 0 packets received, 100% unanswered (0 extra)

# arping -u -c 2 192.168.1.116
ARPING 192.168.1.116

--- 192.168.1.116 statistics ---
2 packets transmitted, 0 packets received, 100% unanswered (0 extra)
root@modef:~#

martyndwheeler · 07-06-2012, 04:17 AM

Did you ever sort this out? I have exactly the same problem on my network. I cannot ping any Linux machines that are wirelessly connected to my router unless they are first pinged by a windows machine, after which time it can be accessed for about a minute before being pinged again. Please help.....

RaisedByWolves · 07-10-2012, 02:50 AM

Sorry, no. I was never able to resolve this. I'm assuming it is an issue with my wireless drivers or Debian.

jschiwal · 07-10-2012, 03:19 AM

Your router may be isolating wireless connections only allowing internet traffic. Wireless can be tricky. My router will stop wireless authentication. I found that this only happens when my laptop is connected on the wired side. Strangely, this still happens after switching to the Tomato firnware!

RaisedByWolves · 04-20-2013, 12:51 AM

Thank you Schiwal, with that tip I believe I have found the problem.

My Linksys Router has a feature on it (which is apparently common) called AP isolation. It isolates wireless devices so they can only communicate to the router, not each other.

It took forever to find, because in my router's settings, it was set to off. However it was indeed on, and toggling that setting on and off was needed to fully disable it.

Since the toggle I haven't had any issues connecting via wireless.