SSH / Telnet Software

Telnet is an application layer protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. SSH was designed as a replacement for Telnet and for unsecured remote shell protocols. The term telnet is also used to refer to the software that implements the client part of the protocol. SSH provides a secure channel over an unsecured network in a client-server architecture, connecting an SSH client application with an SSH server.

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Have two Dell powerconnect 5548's set up in a stack. Recently have been unable to login and when attempting ssh, I get the following error.
Remote side sent disconnect message - type 2 (protocol error): "Connection closed by server: Server reached maximum number of simultaneous connections

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There seems to be a command for other dell switches to clear sessions however I am not seeing anything for the 5500x series. I set a session timeout and even rebooted the switch but I am still getting this error. All line connections show as locked in the web UI however reactivating the locked line through the GUI does not do anything. Anybody more familiar with Dell switches have an idea for how to resolve this error? I can currently manage the switch by console and web ui however it would be great to get remote ssh sessions running again.
Learn SQL Server Core 2016
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I had this question after viewing Unable to login to SFTP (Silvershield).

I have a problem that the software was installed and no one knows what was entered as the password.   I do not have the file name in the help article.   Is there a way to get in to change the password?  We have version 6.1....
Have a Ruby script the ssh into multiple servers. I am trying to modify it so that it would first attempt  to use password and then 2nd attempt use a key.
Have script do each by there self however I need to have one script that will try to use password first then key.

Below is my script:
#!/usr/bin/env ruby
require 'rubygems'
require 'net/ssh'

PASS = 'password'
KEY = "~/.ssh/id_rsa"
hosts = ['host1',  'host2',] 

hosts.each do |host|
  Net::SSH.start(host, USER, :password => PASS, :keys => KEY,
                   :auth_methods => ["password", "keys"], :port => 22,
                   :timeout => 5,
                   :non_interactive => true ) do |ssh|
     result = ssh.exec!('hostname')
     puts result
     result = ssh.exec!('hostname -i')
     puts result
     result = ssh.exec!("echo \'*** ****\'")
     puts result
     puts result

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I know encryption decryption mechanism for a typical HTTPS based communications.

However, Failed to understand the how chemistry between below 2 blocks works  
{private&Public key} ---vs-  {SSL certificate }

Please advice
I generated a new private and public key pair using the following command -
ssh-keygen -t rsa
on my system
And shared it to a team in my company to put that on prod box.
Will that be a problem ? Can anyone take advantage of it. or hack into my system
Hi All, SLES 12: How to disable download & delete privilege for selected user as per request, but upload is always enable, please advise whats the setting.
I want to create a ssh script file to execute .sh file … my user is sudo
I tried with PowerShell but I want automated way to put the password inside the script.... but I didn't find a parameter for that.
also I tried with putty but when I run the cmd file :
putty.exe -ssh admin@9.9.99 -pw "!123!~sasaZ~" -m commands.txt
its's stop and asked me for password !
I have a vb6 program that reads from a *.log file that is being written to via TelNet.  Can that cause records to not be written by TelNet and, if so, how can I avoid that?  

Thank you!
I am making an SFTP connection using JSch libaray in java.
Strangely enough the first time i call the api which internally sftp to the server it succeeds. But the second time it fails.
what could be the reason for that ?

Each time a file gets uploaded to the server the following piece of code gets called :
 private CompletionStage<ChannelSftp> getChannel() {
    return sessionManagerInit
        .thenCompose(__ -> sessionManager.establishConnection(timeoutMillis))
        .thenCompose(__ -> sessionManager.openSftpChannel())
        .exceptionally(throwable -> {
          logger.error("Error in getChannel", throwable).attr("message", throwable.getMessage()).log();
          throw new ChannelException(throwable);

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the code fails in establishConnection.
One thing i noticed is that i am not disconnecting the session or closing the connection explicitly here after all the files are uploaded to the sftp server.
Although each time i upload a file i open a sftp channel and then close it.
So the next time when i make the api call ideally the same connection must be available if only it doesnt get disconnected due to inactivity.
Even in that case establishConnection should make a connection :

But i still dont see why this could be the reason for the failure.
In the first api call everything goes fine..
In the second i see the following JSCH logs :
Disconnection from host ...
Caught an exception, leaving main loop due to Connection reset
[user@ansible01 install]$ ssh-copy-id
/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/user/.ssh/"
/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
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i did migrate a Linux box to another datacenter and I had to re-ip the server. The hostname remains the same.  After migration i came to know there was another server which was communicating with the migrated server with ssh keys authentication.  I have ssh-agent running on serverB which should take care the passphrase. ServerA has been migrated and I did re-ip.  

I did remove serverA entry from known_hosts and did handshake again.

now ServerA has the authorized_keys which is exactly the key from ServerB.  

not sure what is the issue here and why I am getting prompt for passphrase ?  Please help

serverB:~/.ssh> ssh ServerA

Enter passphrase for key '/home/appid/.ssh/id_rsa':  

serverB:~/.ssh> ps aux | grep ssh-agent | grep -v grep
appid 9509  0.0  0.0  18540   556 ?        Ss   Mar10   0:00 /usr/bin/ssh-agent

I have a security related question on Linux Ubuntu.
Can we remove sudo access to root console for power users.
But still allow admin to ssh to the servers with root password.
As a security measure is it a good idea to disable root access to everyone if  connecting to servers remotely.


How to resolve this error SFTP error #3 Permission denied mobaxterm to access on redhat VM lucky directory. thanks
VBOXerr1.txtSSH connection refused when running SSH (putty) from my WINDOWS PC a  an ORACLE LINUX running on the same PC on Oracle Virtual BOX.

PUTTY displays the error:
PUTTY Network  error:  Connection refused  on

Sure, something is wrong. Could you help?


I already attached a log from the Windows8  machine (ipconfig ).
What I am ryng to do is connect from Windows using putty (SSH) to the VM Linux running on the same machine .
Someone can give any advice?

See below the ifconfig of the VM Linux machine:

root@ServidorLinux7 ~]# ifconfig
enp0s3: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet  netmask  broadcast
        inet6 fe80::52d0:9ddb:1f83:48f2  prefixlen 64  scopeid 0x20<link>
        ether 08:00:27:5d:46:25  txqueuelen 1000  (Ethernet)
        RX packets 6787  bytes 4818007 (4.5 MiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 4517  bytes 617833 (603.3 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING>  mtu 65536
        inet  netmask
        inet6 ::1  prefixlen 128  scopeid 0x10<host>
        loop  txqueuelen 0  (Local Loopback)
        RX packets 46  bytes 7314 (7.1 KiB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 46  bytes 7314 (7.1 KiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  …
Hi All,

I setup a Server A as a telnet server. Then client A is using putty to telnet into Server A.
I successfully connect to the server and can run commands but when I try and open an exe. Nothing happens
It just returns  an empty line.When I go to Server A and open command prompt and execute the program it runs inside the command prompt window.
So not sure what I am doing wrong in the telnet setting for the program not to be starting.
After 30+ hours of research and trying different solutions I have found many solutions to each piece of this puzzle but can't quite get them to work together or figure out the best approach so I'm hoping you guys can help.

The goal: Use public IP from a remote server(Ubuntu) as a browser proxy. The kicker is that the server should pass all traffic through to a local machine which has a 4g modem internet connection to use its internet connection. We need to be able to assign fixed IP addresses/IP port combinations to these local modem/s to be used as undetectable browser proxies to make it appear that the browser client is logged in using the mobile internet connection.

I have seen multiple solutions to each part of this including the use of ssh tunnels, dynamic port forwarding/socks, remote port forwarding, squid proxy server/other proxy server software, iptables configs etc..

I have found this solution that I can get traffic to travel from anywhere to my local machine:

//1st terminal establishes connection/tunnel ssh -nN -R 8888:localhost:8889 -i "connection.pem"

//2nd terminal listens on port 8889 netcat -l -p 8889 //this command works and prints abc on the local machine echo "abc" | nc -v xx.xx.xx.xx(remote server ip) 8888

I have also successfully installed a squid proxy server in a docker container and used the following command to open socks connection with reverse forwarded port.

//Socks/Dynamic forwarding with…
Hello Experts,
Seemingly out of the blue (starting July 29th), though possibly corresponding with installing VMware Tools on the server (7/22), or, less likely I think, updating our ERP software including telnet server (7/21) and OS updates (7/21 - see attached), our Server 2012 R2 VM has been acting up.

I have been rebooting a telnet server service daily for two years+ to kick out clients that didn't log out and had their then sessions hang, which frees up licenses for new clients to log on in the morning. Recently, this has caused the server to not accept new connections on port 23. Nothing seems to fix it except for an OS reboot. The corresponding message in the Event Viewer is from AFD:

Closing a TCP socket with local port number 23 in process 16584 is taking longer than expected. The local port number may not be available until the close operation is completed. This happens typically due to misbehaving network drivers. Ensure latest updates are installed for Windows and any third-party networking software including NIC drivers, firewalls, or other security products.

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This happens reliably now every time the telnet service is restarted. The process ID corresponds to the telnet server. Killing the process (that was restarted initially and caused this error) does not then allow connections on 23 - the OS must be rebooted. Disabling and then enabling the network adapter does not help. I reinstalled VMware tools which did not help.

Another error from Tcpip may be related started happening about a week later (8/7) and has been occurring daily or up to six times a day since:

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Hello All,

We receive an instruction to upgrade to Dropbear SSH version, but I have no idea about this. Can you please me understand this please?

I want to automate the file transfer.
FTP Client : Reflection FTP Client
SFTP Server : Tectia SFTP Server.
I tried using similar to winscp scripts powershell but it didnt work.
Can someone help me providing the script which will work to transfer file to sftp server running script.
Authentication method is public key + password authentication and password must be encrypted.
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I had this question after viewing How to connect to multiple parallel SFTP using JSCH?.

Is it possible to have multiple SFTP connections for the same host,username and port??
We have a Linux server and after it was scanned for any security vulnerabilities, we got one about "SSH Weak Algorithms Supported".  I tried to make a change to the ssh_config file under /etc/ssh/ to remove the support for any "arcfour" algorithm, but after another scan, it is still showing that this vulnerability exists.  Can anyone tell me exactly what I need to change?  This is my line in the ssh_config file:

 Ciphers aes128-ctr,aes192-ctr,aes256-ctr,aes128-cbc,3des-cbc

Thanks in advance!
- Christian
I configured new FTP user in ubuntu linux . but connecting to FTP via Filezilla occured this error .
Received unexpected end-of-file from SFTP server Error: Could not connect to server
There is a security system scanner that needs to access a server to scan.  If it states the below, what would be the command to allow?  I've check sshd_config and thought allowed IPs would be in that config.  But it seems I need a command and the system previous setup owner is gone at my current new job.  

RHEL 7.4 Maipo

If you are running IP filters or IP wrappers you will need to permit the systems to access your system via Secure Shell (SSH) on port 22. The IP addresses for the systems are

These are just placeholder IP addresses.  
What would be the command line only to add this?
Hi all,

I've been trying to access our Cisco SG300 via URL and putty and no luck. The switch is fine and running. I've been wanting to go in and bring a port alive.

Earlier, for the first time in weeks the GUI loaded via URL on the browser so I tried to log on and it wasn't doing anything. Also tried HTTPS and nothing (GUI.PNG) also I exit browser and reload it says... Unable to connect, etc on most browsers(cisco_browsers.png)

I also tried console access with PUTTY.
SG300 -> male to male serial cable-> DB9 to USB cable. Device manager shows COM4 so I set that into putty.

Connect to: COM4
Speed: 115200  (have tried 9600)
Data Bits: 8
Stop Bits: 1
Parity: NONE
Flow Control: NONE

SSH and Telnet was also not working.

SSH- file attached (cisco_putty_ssh) ...  "Disconnected: No supported authentication methods available (server sent: public key)

Telnet- file attached (cisco_putty_telnet) ... "Network error: Software caused connection abort"

I've completely rebooted my laptop and the SG300 switch as well.
We use SFTP on our AS400 to Send data to a client on port 10022 (was set up a long time ago), and it works perfectly.  We have a new client who wants us to SFTP using port 22, which is the default port.  When we try to SFTP it tries to use port 10022.  I looked and the SSH config file shows port 22.  Why is SFTP getting port 10022 from, and more importantly how do we change it to use port 22 for this client?

OpenSSH_6.9p1, OpenSSL 1.0.2j  26 Sep 2016                                            
debug1: Reading configuration data /QOpenSys/QIBM/ProdData/SC1/OpenSSH/etc/ssh_config
debug2: ssh_connect: needpriv 0                                                      
debug1: Connecting to [] port 10022.              
debug1: connect to address port 10022: Connection refused            
ssh: connect to host port 10022: Connection refused              
Connection closed

SSH / Telnet Software

Telnet is an application layer protocol used on the Internet or local area networks to provide a bidirectional interactive text-oriented communication facility using a virtual terminal connection. SSH was designed as a replacement for Telnet and for unsecured remote shell protocols. The term telnet is also used to refer to the software that implements the client part of the protocol. SSH provides a secure channel over an unsecured network in a client-server architecture, connecting an SSH client application with an SSH server.

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SSH / Telnet Software