Menu
Reply
  • 1
  • 0
  • 0
leemhenson
Joining in
205 Views
Message 1 of 8
Flag for a moderator

very flaky ssh connections

Hi.

For the last few weeks or so I've had really poor reliability when it comes to making ssh connections (over wifi). For example I can run the following command three times, and the first two times it will work and the third time it will time out:

$ xxxxxx@github.com -vvv
OpenSSH_7.3p1, OpenSSL 1.0.2j 26 Sep 2016
debug1: Reading configuration data ~/.ssh/config
debug1: ~/.ssh/config line 1: Applying options for *
debug1: Reading configuration data /usr/local/etc/ssh/ssh_config
debug2: resolving "github.com" port 22
debug2: ssh_connect_direct: needpriv 0
debug1: Connecting to github.com [192.30.253.113] port 22.
debug1: connect to address 192.30.253.113 port 22: Operation timed out
ssh: connect to host github.com port 22: Operation timed out

I've done the usual power cycling on both my laptop and the Superhub. Visiting github.com in the browser works absolutely fine every time. If I run a speed test I get:

  • Ping: 13ms
  • Download: 55Mbps
  • Upload: 10MBps

Traceroute says:

traceroute to github.com (192.30.253.112), 30 hops max, 64 byte packets
01 * * *
02 82.2.243.13 <10.000ms <0.000ms <10.000ms
03 * * *
04 * * *
05 * * *
06 * * *
07 * * *
08 62.254.42.242 <10.000ms <30.000ms <20.001ms
09 62.254.85.86 <40.000ms <30.001ms <30.000ms
10 * * *
11 84.116.130.66 <130.002ms <130.002ms <130.002ms
12 84.116.130.174 <130.002ms <130.003ms <140.002ms
13 206.126.236.12 <130.002ms <130.002ms <140.003ms
14 129.250.197.74 <130.002ms <130.002ms <140.002ms
15 * * *
16 * * *
17 192.30.253.112 <140.002ms <130.003ms <140.002ms
Traceroute complete.

For what it's worth, my Virgin package is Vivid 150 Optical Fibre, and I've kicked off one of these:

http://www.thinkbroadband.com/ping/share/4fb40b9b96a5a68e25a7479b1617fcee.html

Any ideas on what I can do to diagnose this further?

Cheers

[MOD EDIT: Personal and private information has been removed from this post. Please do not post personal or private information in your public posts. Please review the Forum Guidelines]

0 Kudos
Reply
  • 12.48K
  • 353
  • 1.45K
Forum Team
Forum Team
178 Views
Message 2 of 8
Flag for a moderator

Re: very flaky ssh connections

Hi leemhenson,

Thank you for opting to report this to our Forum, welcome on board Smiley Happy

Interestingly I dealt with another report of this issue earlier today. Please read the customer's post and my reply here.

The fault ticket I've raised, ref: F004864037, is specific to that customer and this would now appear to be a more widespread issue as you are connected to a different CMTS. If you don't mind I'd like to see how the afore-mentioned fault pans out as I suspect it will also impact you. If at any point I feel the need to raise an individual ticket against your connection then I shall do so.

I'll keep an eye on this to see what happens and shall update you accordingly.


Jen
Forum Team



0 Kudos
Reply
  • 12.48K
  • 353
  • 1.45K
Forum Team
Forum Team
161 Views
Message 3 of 8
Flag for a moderator

Re: very flaky ssh connections

Hi leemhenson,

I'm now thinking that I'd like to get this flagged up for you too.

Would you please provide:

  • A traceroute that fails to resolve to github.com
  • A list of times of day that this problem occurs.

Thank you very much Smiley Happy


Jen
Forum Team



0 Kudos
Reply
  • 3
  • 0
  • 0
ronenbarzel
Joining in
124 Views
Message 4 of 8
Flag for a moderator

Re: very flaky ssh connections

Hello, I have found very repeatably that if I execute a series of "scp" commands one after another, then ssh gets blocked entirely for a few minutes.

E.g. just a simple script that looks like this:

 

scp file1.jpg bamboo.dreamhost.com:dir1/file1.jpg
scp file2.jpg bamboo.dreamhost.com:dir2/file2.jpg
scp file3.jpg bamboo.dreamhost.com:dir3/file3.jpg
...etc...
scp fileN.jpg bamboo.dreamhost.com:dir4/fileN.jpg

gets through perhaps half a dozen of them.  Then the ssh connection starts timing out, and it's impossible to establish a new ssh connection to that host.  There's no error, there's simply no response:

$ ssh -v bamboo.dreamhost.com
OpenSSH_7.4p1, LibreSSL 2.5.0
debug1: Reading configuration data /Users/ronen/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Connecting to bamboo.dreamhost.com [66.33.212.111] port 22.
ssh: connect to host bamboo.dreamhost.com port 22: Operation timed out
$

If I stop trying to connect then wait a few minutes, ssh connections can be established again.

Here's a traceroute when ssh was jammed (though it doesn't seem to be different when ssh is jammed) or isn't:

$ traceroute bamboo.dreamhost.com
traceroute to bamboo.dreamhost.com (66.33.212.111), 64 hops max, 52 byte packets
1 routerlogin.net (192.168.0.1) 5.631 ms 2.682 ms 2.578 ms
2 10.234.172.1 (10.234.172.1) 19.964 ms 13.102 ms 8.698 ms
3 sgyl-core-2b-xe-210-0.network.virginmedia.net (62.253.0.97) 11.849 ms 17.479 ms 9.924 ms
4 * * *
5 * * *
6 nrth-ic-1-ae1-0.network.virginmedia.net (62.254.42.218) 20.485 ms 24.708 ms 18.736 ms
7 m674-mp2.cvx1-b.lis.dial.ntli.net (62.254.42.162) 27.431 ms 19.596 ms 19.467 ms
8 ae-11.r24.londen12.uk.bb.gin.ntt.net (195.66.224.138) 18.376 ms 19.276 ms 20.610 ms
9 ae-5.r24.nycmny01.us.bb.gin.ntt.net (129.250.2.18) 119.741 ms 112.178 ms 113.724 ms
10 ae-1.r25.nycmny01.us.bb.gin.ntt.net (129.250.3.207) 118.054 ms 111.784 ms 113.316 ms
11 ae-9.r22.asbnva02.us.bb.gin.ntt.net (129.250.2.149) 117.103 ms 117.436 ms 112.714 ms
12 ae-7.r06.asbnva02.us.bb.gin.ntt.net (129.250.2.121) 117.790 ms 115.733 ms 119.127 ms
13 ae-1.a03.asbnva02.us.bb.gin.ntt.net (129.250.5.214) 112.492 ms 112.092 ms 111.574 ms
14 ae-0.dreamhost.asbnva02.us.bb.gin.ntt.net (129.250.196.242) 116.711 ms 112.044 ms 112.752 ms
15 ip-208-113-156-8.dreamhost.com (208.113.156.8) 120.419 ms 114.814 ms 114.527 ms
16 ip-208-113-156-14.dreamhost.com (208.113.156.14) 118.998 ms 120.808 ms 113.409 ms
17 * * *
18 * * *
19 * * *
20 * * *
21 * * *
22 * * *
23 * * *
24 * * *
25 * * *
26 * * *
27 *^C

I had a long session with a sysadmin at the other end and he verified that the problem wasn't with the server; no firewall or DDOS blocking was happening and he was able to make ssh connections while I was blocked.   So he said to check with my ISP, and I found this thread...

Any way of fixing this would be great.

Thanks!

 

 

 

 

 

0 Kudos
Reply
  • 3
  • 0
  • 0
ronenbarzel
Joining in
112 Views
Message 5 of 8
Flag for a moderator

Re: very flaky ssh connections

Followup: the issue seems to be related to the number or frequency of establishing ssh connections, not the quantity of data.

I was able to work around my problem with a script that opened a single ssh connection, and uploaded very many files (as well as performed some remote commands) through it without any trouble.

0 Kudos
Reply
  • 7.2K
  • 173
  • 420
Forum Team
Forum Team
76 Views
Message 6 of 8
Flag for a moderator

Re: very flaky ssh connections

Hi ronenbarzel, 

 

Welcome to the forums, I am glad to see you managed to get things resolved. 

 

Just as a quick additional I can see your downstream power levels are too low and I would like to get an engineer out to correct this for you. 

 

I will pop you a PM to get this arranged. Keep an eye out for the Purple Envelope, top right hand corner. 

 

Speak to you soon.

 

Emma


New around here? To find out more about the Community check out our Getting Started guide


0 Kudos
Reply
  • 3
  • 0
  • 0
ronenbarzel
Joining in
69 Views
Message 7 of 8
Flag for a moderator

Re: very flaky ssh connections

Hi Emma,

Thanks for the reply.  I did get things working, but it doesn't give me the parallelism that I'd hope for -- ideally i'd open multiple ssh sessions simultaneously so that I can send data in parallel.  So still if it's possible to resolve whatever issue there may be with having multiple ssh sessions that'd be great.

And thanks for noticing--and dealing with--the power levels!

Best

-Ronen

 

0 Kudos
Reply
  • 7.2K
  • 173
  • 420
Forum Team
Forum Team
58 Views
Message 8 of 8
Flag for a moderator

Re: very flaky ssh connections

Hi ronenbarzel, 

 

Thanks for getting back in touch, I am sorry to see it is not quite as you would like it. 

 

Please pop the Hub into modem only mode with the computer in safe mode with networking. Let us know if it makes a difference.

 

Keep us posted. 

 

Emma


New around here? To find out more about the Community check out our Getting Started guide


0 Kudos
Reply