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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18 views

Browsers won't connect to localhost on ubuntu

I am making a simple, custom server (server.c) on my ubuntu platform, and am trying to get a browser to open up an html file (the html file is stored in the same directory as my server.c file), via my ...
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1answer
23 views

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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1answer
33 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 ...
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1answer
86 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. ...
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1answer
150 views

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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2answers
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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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1answer
43 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 ...
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25 views

Unable to access port of AWS EC2

I have a VPN tunnel setup between Local Infrastructure and EC2 instances. I am able to ssh into the EC2 instance means I am able to access port 22 but unable to access 5432 port. Below is Security ...
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1answer
1k 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 ...
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35 views

Hyper-V VM's LocalPorts blocked

I am having issues with Local ports on hyper-V VM's I have enabled Hyper-V on my Windows10 laptop and Deployed windows 2019 sever Virtual machines to create the SCCM Lab environment. All Virtual ...
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1answer
82 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 ...
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54 views

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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1answer
353 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 ...
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1answer
46 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 ...
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1answer
86 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 ...
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1answer
137 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: ...
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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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2answers
338 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 '...
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2answers
400 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 ...
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43 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 ...
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1answer
440 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 ...
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1answer
1k 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 ...
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1answer
3k 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 ...
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0answers
34 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 "*?...
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2answers
501 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 ...
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530 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 ...
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1answer
158 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 ...
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1answer
51 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 ...
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1answer
830 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. ...
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1answer
2k 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/...
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99 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 ...
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1answer
884 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 ...
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2answers
3k views

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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641 views

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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0answers
944 views

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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3answers
1k views

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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1answer
768 views

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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1answer
2k views

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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1answer
8k 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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1answer
17k views

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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2answers
88 views

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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1answer
4k views

Check if HTTP Methods have been Allowed and Enabled on Localhost

I’m running Apache/2.2.15 (Unix) on a RHEL system. My LAMP is running on localhost. I want to check if the HTTP methods: POST GET PUT DELETE are allowed and enabled. I’ve read that they can be ...
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154 views

OpenVPN connected, partial internet [IPv6]

I've got an OpenVPN server set up and it works wonderfully, with all internet traffic using the VPN connection. On one specific WiFi network, I can use telnet/openssl s_client to connect to web ...
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1answer
43 views

Unable to telnet particular server IP from our CentOS 7.2 server

I am unable to telnet a partner server IP (103.x.x.x) from our server. I am getting following error telnet: connect to address 103.x.x.x: Connection timed out but I am able to telnet other server ...
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1answer
8k views

Connecting to Hotmail's IMAP Server using Telnet [closed]

Hotmail appears to have two separate IMAP ports: imap-mail.outlook.com 993 And: imap-mail.outlook.com 143 My guess here is that 143 is unsecured, and 993 is over SSL. However, when I try to ...
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2answers
2k views

Linux - opened port, but still fail to connect to it using telnet

I'm currently working on CentOS 7.3. In order to activate SNMP, I installed it, configured it and successfully started the service using the firewall-cmd command. Now, I realized that I need to ...
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1answer
668 views

Amazon EC2 Ubuntu 16.04 telnet works on some ports and not for others

I am having a strange issue on my newly installed Amazon Ec2 ubuntu 16.04 LTS server. I have a server with ip (10.129.29.46) in a VPC which has the following ports open 80, 443, 11300 and 9000. Port ...
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0answers
190 views

SSH or telnet on other ports is not working from a specific network

We have an Lenovo server working well since one and a half year. Sudenly, we started having issues to connect to it from our office network. I reinstalled ubuntu 16.04 sever on it. It has two ethernet ...
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1answer
34 views

Exchange 2016 is ignoring a single host for SMTP/EWS

We've just completed a deployment and migration from Exchange 2010 to Exchange 2016. Our ticket system connects to an Exchange mailbox to generate tickets. Connections from the ticket system to ...

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