06-20-2018 10:21 PM - edited 06-04-2019 02:40 AM
When I am trying to do SSH to 10.10.20.20 DevBox: CentOS 7 Workstation, it is not not responding and getting hang. I am following steps from https://learninglabs.cisco.com/lab/nxos_telemetry_part1/step/2. But this devbox is responding to ping command. Please help me to fix this issue.
Solved! Go to Solution.
06-21-2018 10:19 PM
Hi Nilesh,
The Devbox should be 10.10.20.25 other than 10.10.20.20. I've tried a new reservation and the devbox is working here.
Thanks,
Bob
06-21-2018 10:19 PM
Hi Nilesh,
The Devbox should be 10.10.20.25 other than 10.10.20.20. I've tried a new reservation and the devbox is working here.
Thanks,
Bob
06-25-2018 03:59 AM
Hi,
I have got the same problem. I am using MacOS X High Sierra and the problem is that i can't ssh to 10.10.20.20 and RDP to 10.10.20.161. I did some troubleshooting and Ping does work with no problems. Also when I am doing telnet to 10.10.20.20 on port 22 then port is open. The problem for me looks like it's locally or because of VPN connection.
Interesting thing is that when I start windows on the same computer via VMware then I can access everything, but I do prefer to learn from my main system which is MacOS X of course.
In Addition there is no device under 10.10.20.25
Could you please help me investigate the problem?
PS: I suppose that all MAC users will have similar problem
Thanks
Adrian
06-25-2018 05:22 AM
Hi Adrian,
What Sandbox lab are you using?
Joe
06-26-2018 06:07 AM
Hi Joe,
I am using followind lab: NX-OS with Nexus 9Kv Lab (devnetsandboxlabs.cisco.com/rave36)
In Addition I did debug ssh on my MACBOOK and it stuck in: ssh2_msg_kexinit sent
BR
Adrian
06-29-2018 04:12 AM
Hi Joe,
Have you dad time to have a look in to this what I wrote?
In addition I have found that there is Packet fragmentation and My question is if may be there is a problem.
Max mtu without fragmentation is 12xx
07-01-2018 12:50 AM
Hi,
I have solved the issue and I would like to share with you hot to fix it.
When you connect to VPN it also negotiate the MTU and in my case it negotiated 1406 MTU.
When I did ping with DF bit set and with my negotiated MTU. Ping didn't work:
root@xxx:~# ping -s 1406 10.10.20.20
PING 10.10.20.20 (10.10.20.20) 1406(1434) bytes of data.
^C
After that I have changed MTU on tunnel interface:
root@xxx:~# ifconfig tun0 mtu 1355
I set maximum possible MTU with no fragmentation.
Now I am able to connect to 10.10.20.20 with no problems
I believe such problem will be not only for Mac users but also for linux users. So this solution will be working for linux based users as well.
07-08-2018 08:44 PM
Hi, this solution worked for me but not with that MTU (1355), for me had to be something under the 12xx range.
Also a quick note for anyone testing this, you should test the ping with the -D flag to avoid fragmentation since Jumbo packets are enabled and you can actually ping all over 8184:
```
daniel$ ping -s 8184 10.10.20.20
PING 10.10.20.20 (10.10.20.20): 8184 data bytes
8192 bytes from 10.10.20.20: icmp_seq=0 ttl=63 time=147.845 ms
8192 bytes from 10.10.20.20: icmp_seq=1 ttl=63 time=147.635 ms
8192 bytes from 10.10.20.20: icmp_seq=2 ttl=63 time=147.429 ms
```
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