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Questions tagged [telnet]

For questions about Telnet, a protocol for bidirectional interactive text-oriented communication with remote hosts via virtual terminals. It is defined in RFC 854.

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Connecting to a DB server using telnet

I have a db server that can only be accessed by from another server[cant access it from my local device] and the DB server can only be accessed using telnet, SSH is not supported by the DB server. My ...
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How to telnet to a unix socket in debian to test memcached

To test memcached on Ubuntu, I would run this command: echo "stats settings" | nc -U /run/mydir/memcached.sock However now I have changed to Debian, and Debian nc does not support the -U ...
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Iptables + telnet not blocking ports

I have a Debian server from which I want to block all incoming and outgoing ports (especially all outgoing email ports), except those that I specifically add in iptables. The current setup I have is ...
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How to set the vty line of R1 and R3 to be access by local local pc only?

Configuring acl(telnet) on vty line
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Could not SSH and when I try to connect to the server using telnet I received the error "could not open connection to the host, on port 22"

I have spin up database server using customer AMI. All of my team members are on same network and I am able to SSH and telnet to the server but one of my team member is not able to SSH and telnet to ...
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Telnet reconnect or maintain session?

We currently have several RFID Scanners connected to the backend via a telnet client. However due to coverage of our wifi these scanners might lose there connection for a small period of time. The ...
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telnet only works one way

I recently cloned two AWS CentOS 7 instances from a physical server. From the first AWS instance, I can telnet on port 22 to the second AWS instance. From the second AWS instance, I cannot telnet to ...
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Allowing IP & Port specific traffic for card terminal

I hope you can help me :) I am setting up a credit card terminal in my store network. (It‘s just a mobile LTE Router with a static IP address and a switch) The payment processing provider requires me ...
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All Outbound Traffic Uses IPV6

I have a Debian 10 server which has postfix installed, each time I try to send outbound mail traffic, the server uses IPV6 over IPV4. This causes postfix to log Connection timed out. I have tried ...
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Postfix + Dovecot and folder "sent mail"

We’re using for sending mails our own mail server Postfix + Dovecot with parameter for Postfix sender_bcc_maps which ensures that sent mail thanks to blind copy (BCC) is also sent to a sender’s ...
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Connecting To 127.0.0.1…Could not open connection to the host, on port 8123: Connect failed

Well aware this has been asked, but I have scoured Google/StackOverflow and tried every single suggested solution, without being able to connect to port 8123 on my local (which is running Windows 10). ...
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How to use curl and telnet instead of cgi-fcgi?

I am using this script.c: #include <fcgi_stdio.h> #include <stdlib.h> int main (void) { while (FCGI_Accept() >= 0) { printf("Status: 200 OK\r\n"); printf("Content-...
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Telnet connects to server but cannot transmit data

Our client has a server and our web apps run on port 443 and 2000. Our client has two groups of IP addresses. One group is for the computers used in the company building. These computers can browse ...
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Simple code running in systemd exits to fast?

I had this old code base running in xinet d. It was basically a simple python script that waited for standard in to come in on a socket, it would do something with it and respond on standard out. ...
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Windows to Linux Ping not working while Telnet works

On Linux we have a service running which is listening on port 9999 but when we try to check it from a Windows machine on same network with PING it says : Ping request could not find host 10.32.9.82:...
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Postfix - How to enable SMTP authentication on local delivery

I have an email server running Postfix. Everything is working fine, However, recently, some internal emails received emails from their own addresses with phishing content. After finding out, I learned ...
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1 answer
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How can I lock down an SSH and/or telnet user to only run a custom shell and no other commands or programs?

I asked this question on stack overflow, but I thought it might be more appropriate here on serverfault, because it has to do with system administration and security. I am looking to prototype a ...
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4 votes
1 answer
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Send test mail using telnet via smtps (465) port

Based on this guide I am trying to send a test email using telnet from linux https://linuxconfig.org/send-an-email-using-telnet but the connection immediately disconnects: $ telnet smtp.gmail.com 465 ...
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telnet disabled, server 2012r2 still listening on port 23

How else can I disable telnet to comply with a security audit? The Telnet services roles are not enabled on this server. But it is LISTENING at 0.0.0.0:23. Also there is no local windows firewall to ...
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Azure VM, unable to connect from internet on ports configured (9089-9095)

I have created a VM on Azure with below steps:- Created VM Assigned a public static IP Created a new Virtual Network (Subnet default - (10.0.0.0/24) Did not create a NSG initially (NIC NSG was NONE - ...
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Host is not resolved but connecting via telnet, can somebody explain how?

In aws ec2 instance, rds host name is not resolved by ping or nslookup but it is still able to reach via telnet or nc how ? ~# nslookup xxxx.rds.amazonaws.com nslookup: can't resolve '(null)': Name ...
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How to connect to mail.hotmail.com via port 25 from DNS as instructed by Outlook

If you read https://sendersupport.olc.protection.outlook.com/pm/troubleshooting.aspx, it says Confirm that your DNS is set up correctly Try connecting to mail.hotmail.com via port 25. If you are ...
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Is there a "server" version of telnet? [closed]

If I want to quickly connect to a socket as a client and type something I can use telnet. Is there a version of telnet or a similar program that provides the server-side of this? In other words, is ...
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how to build a telnet middleware server

I need to comunicate an old crm system with a new asset. Crm system can only send fixed commans over telnet connection but this new asset can only receibe commands via api rest. Im planning to ...
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Service sometimes working, sometimes not working

I want to connect Centos B's 33060 port from Centos A. I can ping Server B. [root@serverb ~]# ping 10.42.40.182 PING 10.42.40.182 (10.42.40.182) 56(84) bytes of data. 64 bytes from 10.42.40.182: ...
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Execute command on LINUX via PUTTY from Windows [duplicate]

I want to open a putty session (SSH) from command line and immediately execute on the remote machine a specific command. Something like: putty.exe -ssh user@host -pw pass123 < "cd /some/...
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Telnet not working with windows 10 [closed]

I am using telnet on windows 10. I would like to manually set get requests to chosen server. If I type (just example it can be any site): telnet www.cnn.com 80 for a second I see message '...
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Test TLS TCP Endpoint

I have TCP endpoint for a Service running with TLS (Self-Signed) Certificate. To test this endpoint I use openssl s_client -connect service.domain.com:5050 which prints CONNECTED(00000006) nothing ...
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VMWare network: some guest service not accessible from host

I have elastic search installed on a guest (CentOS7) on my vmware host, I am able to visit it on the default port 9100: If I access it from the guest directly, it shows differently: If I telnet from ...
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2 votes
1 answer
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Postfix (Imap) with Dovecot: no auth available

I'm using Dovecot to get Imap access to my mail server (on Raspbian). I'm using system users and am able to successfully test logins (doveadm auth test ...). But I'm not able to get auth option via ...
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2 votes
1 answer
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Testing connectivity between Unix and Windows servers

I am doing a failover activity between 2 data centers. In 1 data center, 1 Oracle database on Linux is replicating data to 1 SQL Server database on Windows using a replication tool. There is storage ...
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emulate telnet over ssh

I have a client/server application that work over a telnet connection, and it does not support SSH. Basically the client opens a telnet connection to the server, which starts a specific shell, and the ...
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2 votes
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How to Open Telnet Console in post section of Kickstart [closed]

I want to configure external VxWork based device in post section of kickstart file, this accept telnet based commands. I found following #!/usr/bin/expect -f send -- "terminal length 0\r" expect "*?...
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2 answers
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Unable to connect to AWS ec2 instance public ip via browser

I've newly installed Openresty as the web server on an ec2 instance and its currently running but I can't even view the welcome page when I try to navigate to it via my public ip address at the ...
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Telnet shows blank screen on port 443 but TCP handshake not done

From my windows 10 machine (172.18.164.50) if I do a telnet 172.20.187.10 443 It shows a blank screen as if it is connected. It is totally unespected because in theory a firewall is blocking the ...
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How can I abort a telnet connection attempt? [closed]

Suppose I execute the following in command prompt: telnet XXX.XXX.XXX.XXX 80 half a second later, I realize it would never connect (for whatever reason). I want to abort the connection attempt ...
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Why do we need the host name again when downloading the webpage by using telnet?

I learned you could use telnet to download a webpage(making http request), like telnet www.example.com 80 GET HTTP / HTTP/1.1 HOST: www.example.com then the output would be an html source page or ...
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Why smtp server can not be telnet?

https://www.webdigi.co.uk/blog/2009/how-to-check-if-an-email-address-exists-without-sending-an-email/ I am following the above instruction to telnet an email server of gmail. But I got an error. ...
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EXIM SMTP allows to send mails without login / authentication via telnet to any domain

I'm ashamed, but I have to ask for help. My server is being used for sending spam, I've found out I can simply connect with telnet (edit: from any server in office, home and even directly from CMD/...
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1 vote
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How to set the mode of port? access, trunk, general

I tried to set (change) the mode of my port, and I read the book and followed it step by step. But I still get a lot of error. There were what I input. (Routing) (Interface 0/3)#switchport mode ...
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How can I enable SMTP receipt through firewalld on Linux?

I've leased a dedicated, lightly-managed CentOS7 box from a hosting company. The host came with firewalld installed and running and with its iptables preferences pre-imposed. I was not expecting ...
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Is there a security risk to just having the telnet client installed on Windows?

I was recently asking for the telnet client to be turned on on my Windows install. The devops guy told me it was restricted because it passed people's usernames and passwords through clear text. I ...
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SSH and Telnet connectivity issues. It connects sometimes and sometimes it does not

I have come across a problem with SSH and Telnet wherein the connectivity is slow and drops multiple times. But I see that my network has no problems. When I ping a server, it gives me ttl of 127, ...
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telnet 3-Way Handshake

I'm trying to see a simple 3-Way Handshake using telnet on the Client side and tcpdump on the Server side, both Client and Server are inside VMs. I use telnet this way : telnet 172.10.10.21 80 On ...
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telnet non interactive: connection closed by foreign host

if I do telnet host_ip port < /dev/null Trying host_ip... Connected to host_ip. Escape character is '^]'. Connection closed by foreign host. By checking the wireshark, the client side sends tcp ...
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Telnet through a serial terminal server

I have a Perle IOLAN device like this, and one configuration option is for a serial terminal. The corresponding configuration screen. As you can see, one option is to configure the terminal to ...
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Telnet SMTP gives OK but not accepted or queued message and mails not received

I am trying to debug a CDO.Message.1 error '80040213', The transport failed to connect to the server. So I am testing the connection to the SMTP server via telnet. After entering the DATA I am ...
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5 votes
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10k views

Use telnet to check that VNC port is open

I am supposed to connect to a Mac VNC/ARD server. Let's say that the Mac VNC server has the hypothetical IP address 8.8.8.8. I want to check if the Mac VNC server even listens to the default VNC port ...
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telnet: Unable to connect to remote host: Connection timed out

Setting up a postfix server, trying to figure out why it's not working. Here's a command that I ran while troubleshooting. I expected to be able to connect, but could not. lol@foldingmachine:~$ ...
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How can I run an interactive console program when a user connects via SSH

Looking to start a python program when a user connects to my SSH server. An example use case would be a MUD program (except using SSH and not Telnet). If they somehow exit the program or it errors out,...
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