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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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Cant ssh to my server

I was trying to upgrade debian buster to bullseye, during the installation/upgrade of packages putty crashed. Since then I cant connect anymore to my server. I tried via ssh, telnet, virtualmin(some ...
Anarkie's user avatar
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Connection closed by foreing host - Postifx, Dovecot

2024-02-07T10:44:27.271322+00:00 ubuntuserver postfix/postfix-script[23192]: starting the Postfix mail system 2024-02-07T10:44:27.277625+00:00 ubuntuserver postfix/master[23194]: daemon started -- ...
Doujinx's user avatar
-1 votes
1 answer
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Telnet SmarterMail: 550 This is a submission only port. You must authenticate before sending mail

I have a "newer" server running Windows Server 2019 and I installed Smartermail FREE Edition so I could send mail via PHP/CDONTs from contact forms to my email address. I tried matching the ...
imvain2's user avatar
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connection refused mysql with telnet

i have 2 machines that can see each other and ping my issue is i want to telnet from slave machine to master machine and this is what i get: slave@slave:~$ telnet 192.168.1.131 3306 Trying 192.168.1....
sina kzm's user avatar
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1 answer
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Can't telnet Apache2 Web Server from WAN on port 80

Is there specific port configuration to httpd.conf that opens port 80 aside from using Listen 80 directive? netstat -aon gives LISTENING but I cannot telnet machineName 80 (says failed to connect) PS: ...
SSSOF's user avatar
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104 views

RHEL Server Accepts Telnet from all Clients Except a Rocky Linux VM

I have a few VMs on a XenServer. One is a RHEL 8.7 running SSH server. Another is a Rocky Linux 8 client and also some other Ubuntu and Windows systems. The Ubuntu and Windows systems can telnet to ...
techguy817's user avatar
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1 answer
147 views

How to exit from telnet in xterm (ctrl+], ctrl+'+', ctrl+d) don't work

Can't exit from telnet while connected to host. Commands like (Ctrl+], Ctrl+'+', Ctrl+D) etc. don't work. I have tried all the suggestions from keyboard shortcut to quit 'telnet'. Are there ...
Dmitry Tarasov's user avatar
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276 views

Not receiving any response from SMTP server after successfully connected via openssl or telnet

I am trying to set up my postfix using Gmail smtp relay server. I have set it up in other servers without issues, but I am having difficulty getting it to work in my work network. I tested if there is ...
ricardo3889's user avatar
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1 answer
64 views

What is the name of the string that a service returns when you establish a tcp connection via telnet?

If you telnet to an ssh server, it will establish a connection and return a string, something like SSH-2.0-OpenSSH.... etc. Something similar happens if you connect to a mysql server. What exactly is ...
cat pants's user avatar
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Cisco Switch - Enable Telnet using HTTP

I'm trying to automate the configuration process of a Cisco switch (SG-300). I was able to automate everything I need using telnet, but the last issue I still have is to enable telnet itself. For now ...
Outman's user avatar
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Automate time and date through telnet

im not very clued up with telnet commands but i am looking to automate logins for a device we use in the field. we are having issues with Cmos batteries and every time the power goes out (6 times a ...
Warren's user avatar
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601 views

Linux: telnet arrives to target but no response

We have server in AWS that's trying to connect over TCP to an application in an on premise server but fails. Initially we thought it might be routing/firewall issues so we tried to connect to that ...
Tomer Arazy's user avatar
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1 answer
3k views

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 ...
run_the_race's user avatar
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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 ...
Sem van den Broek's user avatar
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455 views

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 ...
DW24da's user avatar
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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 ...
hokie1999's user avatar
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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 ...
maxig's user avatar
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2 votes
1 answer
327 views

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 ...
Ruby's user avatar
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0 answers
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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 ...
Nichlaus's user avatar
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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). ...
KateMak's user avatar
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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-...
FAQ's user avatar
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1 answer
671 views

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 ...
zarax's user avatar
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1 answer
270 views

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. ...
Codejoy's user avatar
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1 answer
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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:...
Ehsan Sajjad's user avatar
2 votes
2 answers
3k views

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 ...
Vu Hoang Long's user avatar
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1 answer
356 views

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 ...
derekmc's user avatar
7 votes
3 answers
15k views

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 ...
u123's user avatar
  • 277
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1 answer
631 views

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 ...
Benjy's user avatar
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0 answers
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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 - ...
Ujwal Tamminedi's user avatar
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0 answers
618 views

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 ...
Smart Athiyas's user avatar
1 vote
1 answer
1k views

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 ...
cilapo1541's user avatar
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1 answer
172 views

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 ...
CaptainCodeman's user avatar
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1 answer
215 views

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 ...
user2977753's user avatar
1 vote
1 answer
145 views

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: ...
Tester's user avatar
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1 answer
6k views

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/...
Mr.Eddart's user avatar
  • 111
-1 votes
2 answers
1k views

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 '...
FrenkyB's user avatar
  • 130
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2 answers
2k views

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 ...
rp346's user avatar
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0 answers
131 views

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 ...
mdivk's user avatar
  • 145
2 votes
1 answer
1k views

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 ...
User Rebo's user avatar
  • 123
2 votes
1 answer
2k views

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 ...
user528701's user avatar
1 vote
1 answer
8k views

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 ...
Jose L Martinez-Avial's user avatar
2 votes
0 answers
53 views

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 "*?...
ImranRazaKhan's user avatar
1 vote
2 answers
4k views

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 ...
Joshua's user avatar
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0 votes
0 answers
1k views

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 ...
user506420's user avatar
0 votes
1 answer
1k views

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 ...
kevin's user avatar
  • 246
1 vote
1 answer
340 views

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 ...
Hang Chen's user avatar
  • 113
-1 votes
1 answer
2k views

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. ...
user1424739's user avatar
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0 votes
1 answer
5k views

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/...
Mateusz's user avatar
1 vote
0 answers
337 views

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 ...
Steve's user avatar
  • 11
0 votes
1 answer
4k views

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 ...
dg99's user avatar
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