Score:2

Ubuntu

Unable to SSH to remote computer

2.1

12/1/23, 7:35 AM

I have two proxy (two ip address) connections in my Ubuntu computer, and I am trying to connect through ssh to my university supercomputer using "corkscrew", but not able to connect, it fails as

Couldn't establish connection to proxy: Connection timed out
kex_exchange_identification: Connection closed by remote host

Could you please help me out here ?

I am able to connect to same supercomputer following the same process from another ubuntu computer which has only single ip

output of ssh -v:

sachin@localhost:~$ ssh -v sachinv@atulya.compunet.barc.in
OpenSSH_8.2p1 Ubuntu-4ubuntu0.5, OpenSSL 1.1.1f  31 Mar 2020
debug1: Reading configuration data /home/sachin/.ssh/config
debug1: /home/sachin/.ssh/config line 1: Applying options for *.compunet.barc.in
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: include /etc/ssh/ssh_config.d/*.conf matched no files
debug1: /etc/ssh/ssh_config line 21: Applying options for *
debug1: Executing proxy command: exec corkscrew compunetgw.barc.gov.in 8080 atulya.compunet.barc.in 22 ~/.ssh/proxyauth
debug1: identity file /home/sachin/.ssh/id_rsa type 0
debug1: identity file /home/sachin/.ssh/id_rsa-cert type -1
debug1: identity file /home/sachin/.ssh/id_dsa type -1
debug1: identity file /home/sachin/.ssh/id_dsa-cert type -1
debug1: identity file /home/sachin/.ssh/id_ecdsa type -1
debug1: identity file /home/sachin/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/sachin/.ssh/id_ecdsa_sk type -1
debug1: identity file /home/sachin/.ssh/id_ecdsa_sk-cert type -1
debug1: identity file /home/sachin/.ssh/id_ed25519 type -1
debug1: identity file /home/sachin/.ssh/id_ed25519-cert type -1
debug1: identity file /home/sachin/.ssh/id_ed25519_sk type -1
debug1: identity file /home/sachin/.ssh/id_ed25519_sk-cert type -1
debug1: identity file /home/sachin/.ssh/id_xmss type -1
debug1: identity file /home/sachin/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.2p1 Ubuntu-4ubuntu0.5
Couldn't establish connection to proxy: Connection timed out
kex_exchange_identification: Connection closed by remote host

output of ip a

sachin@localhost:~$ ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever    
2: enp1s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 00:e0:4c:68:12:d2 brd ff:ff:ff:ff:ff:ff
    inet 10.143.111.41/24 brd 10.143.111.255 scope global noprefixroute enp1s0
       valid_lft forever preferred_lft forever
    inet6 fe80::b3fe:fd97:d21c:6b88/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever      
3: enp4s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 70:85:c2:ba:10:14 brd ff:ff:ff:ff:ff:ff
    inet 10.15.111.45/24 brd 10.15.111.255 scope global noprefixroute enp4s0
       valid_lft forever preferred_lft forever
    inet6 fe80::b524:bbb9:23f7:32e9/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever

output of ip route

sachin@localhost:~$ ip route
default via 10.143.111.1 dev enp1s0 proto static metric 20100
default via 10.15.111.1 dev enp4s0 proto static metric 20101
10.15.91.230 via 10.15.111.1 dev enp4s0
10.15.111.0/24 dev enp4s0 proto kernel scope link src 10.15.111.45 metric 101'     
10.143.111.0/24 dev enp1s0 proto kernel scope link src 10.143.111.41 metric 100'      
90.3.15.135 via 10.15.111.1 dev enp4s0
169.254.0.0/16 dev enp1s0 scope link metric 1000

626

1 + 8

server

ssh

networking

proxy

Serg

12/1/23, 9:20 AM

Run `ssh` with `-v` to obtain more detailes on your connection. It may help you find answer or add its output to your question.

Esther

12/1/23, 2:43 PM

no, the suggestion was to use `-v` (verbose) not `-V` (version). use `ssh -v username@hostname` or however you would normally run ssh, but with the `-v` (lowercase) flag included. That will give you extra information about exactly what is happening.

Esther

12/1/23, 2:45 PM

https://serverfault.com/questions/1015547/what-causes-ssh-error-kex-exchange-identification-connection-closed-by-remote a bunch of suggestions on why this might happen

2.1

12/1/23, 6:55 PM

@Esther, Oh! Thanks, Tomorrow, I will check it and update the question accordingly.

2.1

12/2/23, 4:43 AM

@Serg, added now

2.1

12/2/23, 4:43 AM

@Esther pl have a look on post now

muru

12/2/23, 4:50 AM

Also add the output of `ip a` and `ip route -n`, please.

2.1

12/2/23, 6:00 AM

@muru added, you may now check it

Score:0

Ubuntu

niyaz

12/27/23, 6:04 AM

I assume ip route show still shows same output.

Run the following commands and try to connect again:

$ip route add default via 10.143.111.1 dev enp1s0 proto static metric 20102
$ip route del default via 10.143.111.1 dev enp1s0 proto static metric 20100

[Edit]

In case operation is not permitted, execute with root previleges:

$sudo ip route add default via 10.143.111.1 dev enp1s0 proto static metric 20102
$sudo ip route del default via 10.143.111.1 dev enp1s0 proto static metric 20100

+ 3

2.1

12/28/23, 7:43 AM

1: Yes, same output. 2: It says `RTNETLINK answers: Operation not permitted `

niyaz

12/28/23, 9:50 AM

You need to execute these commands with root previleges. I added `sudo` commands.

2.1

1/12/24, 5:06 AM

Ok, I will do, thanks

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Unable to SSH to remote computer

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