debugging SSH problem in LAN

lleb · 04-29-2020, 02:43 PM

in all things look like they should work. just fyi, the MTR you displayed above is not pointing to the same IP as the ssh log files are showing for the Old laptop. Ensure it is pointing to the correct IP.

new (192.168.1.171) != old.local ([192.168.1.86]

Have you attempted disabling the eth0 card and only allowing the laptop to use the wifi card?

piramiday · 04-29-2020, 02:47 PM

Quote:

Originally Posted by lleb

in all things look like they should work.

I know! I've been troubleshooting ssh stuff for years, so I'm sure that the problem will be very quirky.

Quote:

Originally Posted by lleb

just fyi, the MTR you displayed above is not pointing to the same IP as the ssh log files are showing for the Old laptop. Ensure it is pointing to the correct IP.

on the contrary, it does. the first line in the MTR log is the host that mtr is running on (that is, new, 192.168.1.171), while the first result in the table contains the target (that is, old, 192.168.1.86).

Quote:

Originally Posted by lleb

Have you attempted disabling the eth0 card and only allowing the laptop to use the wifi card?

when I'm trying my wireless tests, my ethernet cable is not connected, so I don't think there would be any confusion with respect to the dual interface.

piramiday · 05-01-2020, 01:17 PM

Quote:

Originally Posted by Turbocapitalist

Code:

ssh -p 2200 -o IPQoS=0 user@old
ssh -p 2200 -o IPQoS=throughput user@old
ssh -p 2200 -o IPQoS=lowdelay user@old
ssh -p 2200 -o IPQoS=reliability user@old

tried, and the same happens: ssh hangs up, there are no interesting debug lines to take a look at.
this is really unnerving. any further suggestion?

michaelk · 05-01-2020, 05:51 PM

Just out of curiosity does networking work in general on old except for ssh?

Just for fun try running a simple chat server and see.

On old
netcat -l 2200

On new
netcat old_IP_address 2200

Not what you type on one computer and when you press enter it should be displayed on the other.

Make sure you have stopped all the other ssh servers if still running.

scasey · 05-01-2020, 06:01 PM

Quote:

Originally Posted by piramiday

when I'm trying my wireless tests, my ethernet cable is not connected, so I don't think there would be any confusion with respect to the dual interface.

I have seen laptops that continue to try to use the wired connection even when there's no wire plugged in...and laptops that require the wired connection to be disabled befort the wireless connection will work.

Going to repeat lleb's suggestion that you disable the wired connection (in addition to unplugging the cable)

Another thought: Are you sure there's not a duplicate IP address on the LAN?

michaelk · 05-01-2020, 06:04 PM

That was going to be my next question...

piramiday · 05-01-2020, 06:35 PM

Quote:

Originally Posted by scasey

I have seen laptops that continue to try to use the wired connection even when there's no wire plugged in...and laptops that require the wired connection to be disabled befort the wireless connection will work.

Going to repeat lleb's suggestion that you disable the wired connection (in addition to unplugging the cable)

I have tried that, but I will try again.

Quote:

Originally Posted by scasey

Another thought: Are you sure there's not a duplicate IP address on the LAN?

yes, of course, I've just checked that my devices have non-clashing addresses (everything is set to DHCP and the router is fine, anyway)...

for the rest, the network (even wireless!) is working good, even torrent reaches 2+ MBps speeds.

I'll try the netcat suggested commands and let you know.