Is there any way to remote control GRUB? I am interested in not having to walk to the machine when it reboots. As such, I am only interested in non-virtualized solutions. In particular, I want remote access to the GRUB console. The ability to select an entry, or edit the options, or even do something completely new. In short, full control. I would be interested in solutions involving VNC, SSH, telnet, or even raw network connections (via netcat or the like). Or something else if there is such a (software) solution. (Security is not *yet* a concern.) Note that I'm not interested in remote control of the booted OS. I also want more direct control than grub-reboot provides. Since everyone is suggesting it: I am **not** interested in a device specific **hardware** solution. I want something I can install on dozens of machines in their GRUB configuration to allow their GRUB boots to be remote controlled.

I'm building a simple shell server using raw Python sockets (not using telnetlib). The client connects using PuTTY with the Telnet connection type. The server displays a basic prompt like: [user@hostname:~]# --- ## The issue: ## When I type a command (for example, wh0ami) and press Ctrl+C, the entire line is wiped and only a fresh prompt appears: [user@hostname:~]# wh0ami ← typed input ^C ← pressed Ctrl+C [user@hostname:~]# ← result: input line cleared --- ## What I expect: ## In typical terminal behavior (like Bash or real Telnet servers), I would expect to see something like: [user@hostname:~]# wh0ami^C [user@hostname:~]# But in my case, the previously typed input disappears completely after pressing Ctrl+C. --- ## Notes: ## - I’m not using raw terminal mode — and I’m unable to use it for my use case. --- ## Question: ## Why does Ctrl+C cause the current input line to be cleared in this setup? Is this normal Telnet behavior, or am I missing something related to how the input buffer or terminal display should be handled? What's the solution to this? Thanks in advance. ---

Is it possible to do the following by expect script? I have Linux server that connected to **linux_machine1** and **linux_machine1** connected to **linux_machine2** My Linux server have access only to **linux_machine1** ( linux server can telnet to **linux_machine1** but can’t telnet to **linux_machine2** ) But from **linux_machine1** I have access VIA telnet to **linux_machine2** So my question is: I need to develop expect script that perform telnet from the Linux server to **linux_machine1** then expect will perform telnet to **linux_machine2** from **linux_machine1** and will copy the **/etc/hosts** file from **linux_machine2** to my Linux server Is this scenario can be implemented by expect script? Short example that descript the process: ( run expect from Linux server ) --> linux_machine1 --> linux_machine2 Linux server <-- /etc/hosts from linux_machine2 <-- * remark - expect script need to be activate from the linux server

With ufw disable on remote postgres system i'm able to connect from my local system However, the connection does not work when I ufw enable as shown below: C:\Users\HOME>telnet 80.240.24.195 5432 Connecting To 80.240.24.195...Could not open connection to the host, on port 5432: Connect failed Below is my postgres configuration at the time of restart. cat /etc/postgresql/12/main/postgresql.conf # - Connection Settings - listen_addresses = '*' # what IP address(es) to listen on; # comma-separated list of addresses; # defaults to 'localhost'; use '*' for all # (change requires restart) port = 5432 # (change requires restart) max_connections = 100 # (change requires restart) #superuser_reserved_connections = 3 # (change requires restart) unix_socket_directories = '/var/run/postgresql' # comma-separated list of directories cat /etc/postgresql/12/main/pg_hba.conf # Database administrative login by Unix domain socket local all postgres peer # TYPE DATABASE USER ADDRESS METHOD # "local" is for Unix domain socket connections only local all all peer # IPv4 local connections: host all all 127.0.0.1/32 md5 host all all 0.0.0.0/0 md5 # IPv6 local connections: host all all ::1/128 md5 telnet works when tried from the postgres host itself, but then I try to make the connection from my local laptop it fails. root@DKERP:/# ufw status numbered Status: active To Action From -- ------ ---- [ 1] 22 ALLOW IN Anywhere [ 2] 8069 ALLOW IN Anywhere [ 3] 443/tcp DENY IN Anywhere [ 4] 443 DENY IN Anywhere [ 5] 80/tcp DENY IN Anywhere [ 6] 80,443,5432/tcp DENY IN Anywhere [ 7] 80 DENY IN Anywhere [ 8] 4433/tcp DENY IN Anywhere [ 9] 5432/tcp ALLOW IN Anywhere 22 (v6) ALLOW IN Anywhere (v6) 8069 (v6) ALLOW IN Anywhere (v6) 443/tcp (v6) DENY IN Anywhere (v6) 443 (v6) DENY IN Anywhere (v6) 80/tcp (v6) DENY IN Anywhere (v6) 80,443,5432/tcp (v6) DENY IN Anywhere (v6) 80 (v6) DENY IN Anywhere (v6) 4433/tcp (v6) DENY IN Anywhere (v6) 5432/tcp (v6) ALLOW IN Anywhere (v6) Can you please suggest what needs to be further done to get the postgres to connect to work from my local laptop?

I have a problem with my script. It seems my password is wrong. #!/usr/bin/expect set ip [lindex $argv 0] spawn telnet $ip set timeout 10 expect "Login:" send "administrator\r" expect "Password:" send "123456" send "\r" It says, login incorrect. But it works, when i use cmd on Windows to telnet to my phone, it works with "administrator" and 123456 as password. I don't know why in my script, I could not log on successfully. I have to use this script to downgrade/upgrade my phones.

I need a tool that tells me if a connection to a host is open or not -- no data to send or receive, just see if the connection is successful. Today I use telnet. $ telnet myhost myport Trying 192.168.1.99... Connected to myhost. Escape character is '^]'. ^[^] telnet> quit Connection closed. ... but I need to have manual input there: the ^] and then also the quit. I need to check several hosts, and that's too much for my simple method. How can I do check for connectivity to multiple hosts more effectively? I would prefer to use a pre-existing tool.

Problem: I have to configure 3 Linux instances that run on docker containers on OpenStack. Routers: Rout, Pout, Mout Rout - should block SMTP & Telnet connections that come from HostR1 on interface sw0.4 and try to go outside the LAN/station (i.e. any other interface) Pout - should block any connections coming from HostP1 trying to access Mout on port 9139 that runs a python tracker script (UDP) Mout - should block ALL external connections (i.e. IPs outside the station) toward HostM1 except icmp and ssh. ! Important: Do not block connections and answers initialized by and towards HostM1. Use stateful rules (Connection tracking)! Mout is connected to Rout on interface sw0.5 and Rout is connected to MainHost on interface to-host. MainHost is also connected to Pout on interface or-pout. My solution which does not work: On Rout: up iptables -A FORWARD -s 10.26.102.67 -p tcp --dport telnet -j REJECT up iptables -A FORWARD -s 10.26.102.67 -p tcp --dport 25 -j REJECT iptables -L -n -v: Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) pkts bytes target prot opt in out source destination 1 60 REJECT tcp -- * * 10.26.102.67 0.0.0.0/0 tcp dpt:23 reject-with icmp-port-unreachable 0 0 REJECT tcp -- * * 10.26.102.67 0.0.0.0/0 tcp dpt:25 reject-with icmp-port-unreachable On Pout: up iptables -A FORWARD -s 10.26.102.194 -p udp -d 10.26.102.66 --dport 9123 -j REJECT up iptables -A FORWARD -s 10.26.102.194 -p udp -d 10.26.102.129 --dport 9123 -j REJECT up iptables -A FORWARD -s 10.26.102.194 -p udp -d 172.30.139.245 --dport 9130 -j REJECT up iptables -A FORWARD -s 10.26.102.194 -p udp -d 172.30.139.241 --dport 9130 -j REJECT On Milano: -no solution yet The commands seen above on Rout and Pout are in a .conf file which apply on reboot or by using: ifdown --force -a && ifup -a. ifdown-ng is already installed & I can't install no other packages on these instances because my instances will break. I can see that the first rule on Rout rejected some packages but the checker I am using still says: WARNING: some required outbound traffic is blocked (try to remove some rules)!

I have a device (RELAY) I am able to telnet into using its IP address from an linux machine (CLIENT) and I'd like to copy a file from the RELAY to the CLIENT. I have very limited privileges on RELAY, but I can view a list of files on it with file dir, and then I should be able to download a file from it using YModem, per the manufacturer, who instructed that the command to send the file is

file read filename.ext

After typing that it displays

> #000 Ready to send file

but I'm not sure how to set up a method to receive the file on CLIENT I have full access to. I've read in this post to receive using minicom, but that appears to be for a serial connection and I'm doing this over a TCP network. I've tried with sz as well and tried to use the --tcp options, but again am not sure if it's simply me not understanding which options to use or if this method isn't correct. What are possible methods for me to connect to RELAY from CLIENT and tell it I'm ready to receive the file? (edit) I had a request to edit this question about why it's different than the one I linked to, and the reason it's different is that for my application I'm using telnet over TCP and the previously linked discussion is using a serial connection.

I'm setting up an OpenVPN access server and I continuously get the error "connection refused" on my client(s).  So I decided to start debugging from the beginning (the server) and tried

telnet 127.0.0.1 2194

The result:

openvpn_as_test_1:~$ telnet 127.0.0.1 2194
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

So this means the issue is on the server.  So I checked if the port was open in ufw with sudo ufw status and noticed the port was not allowed by the firewall.  After adding the port with ufw allow 2194/udp (and ufw allow 2194/tcp even when this is needed), I checked ufw status again, and this was the result:

Status: active

To                         Action      From
--                         ------      ----
2194/udp                   ALLOW       Anywhere
2194/tcp                   ALLOW       Anywhere
22                         ALLOW       Anywhere
2194/udp (v6)              ALLOW       Anywhere (v6)
2194/tcp (v6)              ALLOW       Anywhere (v6)
22 (v6)                    ALLOW       Anywhere (v6)

The port is allowed by the internal firewall, so I tried telnet 127.0.0.1 2194 again and guess what: still connection refused:

openvpn_as_test_1:~$ telnet 127.0.0.1 2194
Trying 127.0.0.1...
telnet: Unable to connect to remote host: Connection refused

Ok, what else could be the problem?  Maybe telnet does not work properly, so I tried:

openvpn_as_test_1:~$ telnet 127.0.0.1 22
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3

Great, telnet is working fine, so… let's check netstat to see if we listen to port 2194:

openvpn_as_test_1:~$ netstat -al | grep "LISTEN"
tcp        0      0 0.0.0.0:943             0.0.0.0:*               LISTEN
tcp        0      0 localhost:domain        0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:ssh             0.0.0.0:*               LISTEN
tcp        0      0 0.0.0.0:https           0.0.0.0:*               LISTEN
tcp        0      0 localhost:904           0.0.0.0:*               LISTEN
tcp        0      0 localhost:905           0.0.0.0:*               LISTEN
tcp        0      0 localhost:906           0.0.0.0:*               LISTEN
tcp        0      0 localhost:907           0.0.0.0:*               LISTEN
tcp        0      0 localhost:908           0.0.0.0:*               LISTEN
tcp        0      0 localhost:909           0.0.0.0:*               LISTEN
tcp6       0      0 [::]:ssh                [::]:*                  LISTEN
unix  2      [ ACC ]     SEQPACKET  LISTENING     13660    /run/udev/control
unix  2      [ ACC ]     STREAM     LISTENING     22260    /run/user/1000/systemd/private
unix  2      [ ACC ]     STREAM     LISTENING     22264    /run/user/1000/gnupg/S.gpg-agent.ssh
unix  2      [ ACC ]     STREAM     LISTENING     22265    /run/user/1000/snapd-session-agent.socket
unix  2      [ ACC ]     STREAM     LISTENING     22266    /run/user/1000/gnupg/S.dirmngr
unix  2      [ ACC ]     STREAM     LISTENING     22267    /run/user/1000/gnupg/S.gpg-agent.extra
unix  2      [ ACC ]     STREAM     LISTENING     22268    /run/user/1000/gnupg/S.gpg-agent.browser
unix  2      [ ACC ]     STREAM     LISTENING     22269    /run/user/1000/gnupg/S.gpg-agent
unix  2      [ ACC ]     STREAM     LISTENING     13568    /run/systemd/private
unix  2      [ ACC ]     STREAM     LISTENING     13578    /run/systemd/journal/stdout
unix  2      [ ACC ]     STREAM     LISTENING     16810    /run/uuidd/request
unix  2      [ ACC ]     STREAM     LISTENING     16816    /var/run/dbus/system_bus_socket
unix  2      [ ACC ]     STREAM     LISTENING     16828    /run/acpid.socket
unix  2      [ ACC ]     STREAM     LISTENING     16830    /run/snapd.socket
unix  2      [ ACC ]     STREAM     LISTENING     16832    /run/snapd-snap.socket
unix  2      [ ACC ]     STREAM     LISTENING     13662    /run/lvm/lvmpolld.socket
unix  2      [ ACC ]     STREAM     LISTENING     13839    /run/lvm/lvmetad.socket
unix  2      [ ACC ]     STREAM     LISTENING     16861    /var/lib/lxd/unix.socket
unix  2      [ ACC ]     STREAM     LISTENING     20300    /usr/local/openvpn_as/etc/sock/sagent
unix  2      [ ACC ]     STREAM     LISTENING     20303    /usr/local/openvpn_as/etc/sock/sagent.localroot
unix  2      [ ACC ]     STREAM     LISTENING     20304    /usr/local/openvpn_as/etc/sock/sagent.api
unix  2      [ ACC ]     STREAM     LISTENING     16865    @ISCSIADM_ABSTRACT_NAMESPACE

Port 2194 is not listed here. Ok, now I have no idea how to continue. Where is my issue?

I have an attendance device running Linux OS. I can connect this device via telnet session. There are some files in the device that I would like to download and upload with new files. How can I do that? I have very low knowledge on Linux OS. Would you please help!

After searching in google I found out that we can telnet to web-server to its http port and use GET to retrieve a html page. For ex: $ telnet web-server-name 80 But I am not able to understand how is this possible ? I thought that if port 80 is for http server, then port 80 will only listen for http requests. But how am I able to telnet to an HTTP port ? Aren't telnet and HTTP two different protocol ?

I'm trying to set up some telnet commands in ~/.telnetrc and they are not being read. The file is

DEFAULT
  mode line

When I go into telnet and do a "display", I get ...

environ         change environment variables ('environ ?'
telnet> display
will flush output when sending interrupt characters.
won't send interrupt characters in urgent mode.
won't read the telnetrc files.
won't map carriage return on output.
will recognize certain control characters.

 Transcribed from [this image , which appears to be cropped.] OS is Ubuntu 18.04. Is something needed to tell telnet to read the .telnetrc file at startup?

When I was using Telnet to remotely access my target computer on Windows and conducting latency testing with cyclictest, after several hours of execution, I suddenly found that the telnet connection was interrupted: C:\Users\guoya>telnet 192.168.5.1 ... 遗失对主机的连接。(Lost connection to host) At this time, I saw the following message appearing on my target computer, as if the network card eth2 had been restarted: [18825.382832] asix 1-6:1.0 eth2: Link is Up - 100Mbps/Full - flow control rx/tx However, at this time, no one or any other process was operating the target device. Of course, there is no process operating eth2 at this moment. My target computer is using a system that I compiled kernel 6.4.0 to generate bzImage and compiled busybox to generate the root file system, # taskset -c 2 cyclictest -p 80 -t 1 -n -i 1000 -l 100000000000 /dev/cpu_dma_latency set to 0us policy: fifo: loadavg: 1.36 1.22 1.14 1/127 1617 T: 0 ( 1553) P:80 I:1000 C:11258227 Min: 2 Act: 3 Avg: 3 Max: 21

Telnet client is said to communicate only with servers which are based on TCP, not with those on UDP. What is the counterpart of telnet client for servers based on UDP?

I'm using telnet to connect to a serial port via a TCP/IP server. I need a raw, unfiltered, unbuffered connection, and can get most of the way there, but no matter what I do telnet sends protocol negotiation commands when it connects. This is strange, because "man telnet" page says: When connecting to ports other than the telnet port, telnet does not attempt telnet protocol negotiations. This makes it possible to connect to services that do not support the telnet protocol without making a mess. But, although I'm connecting to a non-standard port, telnet negotiates: linuxdev:~ griscom$ telnet 172.16.250.49 2023 Trying 172.16.250.49... Negotiating binary mode with remote host. Connected to 172.16.250.49. Escape character is '^]'. And, as the man page warns, this makes a mess. Is there a way to use telnet as a completely transparent TCP/IP client? Or, is there some other tool I could use? Details: * Running telnet on an Ubuntu 22.04 system * Server is a [USR-TCP232-T2 ethernet to serial converter](https://www.pusr.com/products/serial-to-ethernet-converter-modules-usr-tcp232-t2.html) * Serial port is connected to a Linux system's console, so I need unbuffered transparency so I can, e.g. run vim or type control characters Edit: I figured out the problem. telnet by default runs in "line" mode, collecting characters and sending them the next time a CR is typed. I need it to run in "character" mode, where it sends data as-is. Problem: I can't set "character" mode without telnet negotiating that change with the other end of the line. Proof: if I connect to the serial adapter with an unconfigured telnet, I'll get no negotiation characters sent to the adaptor. But, if I use ^] to drop into command mode, and then type mode character, telnet will immediately negotiate with the other end, making a mess. (The same thing happens if I use a .telnetrc file to configure the connection to character mode.) So, there's no way for telnet to connect to a port in "character" model without sending spurious command bytes to that port. I'll need a different solution.

We can use the following in order to test telnet VIA port; in the following example we test port 6667: [root@kafka03 ~]# telnet kafka02 6667 Trying 103.64.35.86... Connected to kafka02. Escape character is '^]'. ^CConnection closed by foreign host Since on some machines we can't use telnet (for internal reasons) what are the alternatives to check ports, as telnet?

I don't suppose that sSMTP will work for just sending mail on the localhost? nicholas@mordor:~$ nicholas@mordor:~$ sudo cat /etc/ssmtp/ssmtp.conf # # Config file for sSMTP sendmail # # The person who gets all mail for userids < 1000 # Make this empty to disable rewriting. root=postmaster # The place where the mail goes. The actual machine name is required no # MX records are consulted. Commonly mailhosts are named mail.domain.com mailhub=mail # Where will the mail seem to come from? #rewriteDomain= # The full hostname hostname=mordor.saundersconsulting.tech # Are users allowed to set their own From: address? # YES - Allow the user to specify their own From: address # NO - Use the system generated From: address #FromLineOverride=YES nicholas@mordor:~$ nicholas@mordor:~$ sudo cat /etc/ssmtp/revaliases # sSMTP aliases # # Format: local_account:outgoing_address:mailhub # # Example: root:your_login@your.domain:mailhub.your.domain[:port] # where [:port] is an optional port number that defaults to 25. nicholas@mordor:~$ nicholas@mordor:~$ swaks --to root@mordor.saundersconsulting.tech --from nicholas@mordor.saundersconsulting.tech --server mordor.saundersconsulting.tech === Trying mordor.saundersconsulting.tech:25... *** Error connecting to mordor.saundersconsulting.tech:25: *** IO::Socket::INET6: connect: Connection refused nicholas@mordor:~$ nicholas@mordor:~$ hostname mordor.saundersconsulting.tech nicholas@mordor:~$ nicholas@mordor:~$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 23.10 Release: 23.10 Codename: mantic nicholas@mordor:~$ There's no mention of anything except for gmail in mail.log and mail.err which were attempted previously. To my understanding sSMTP only will relay e-mail. notable result: nicholas@mordor:~$ nicholas@mordor:~$ ssmtp nicholas@mordor.saundersconsulting.tech subject:ping ssmtp: Cannot open mail:25 nicholas@mordor:~$ that sSMTP cannot open port 25?

I am asking this question because I am not meeting UDP and telnet often... To prepare myself for a development, I am reading a documentation where I will have to connect to a telnet://x.y.z:4161 url. I know, because one at work told me, that it's an UDP server that is behind, but what if I didn't know that, would tell me this? the 4161 port, that is dedicated for UDP exchanges, I think. But could it be also the telnet:// protocol mention that carries this information? What does the telnet: protocol means here? "_I don't know exactly the kind of network communication I have here_"?

Our client uses Termtek terminals to connect to their Universe platform. More terminals needed and we can't get any. The alternative is to get winboxes and run wintegrate or try and get a Linux terminal working. Configured xterm with keybindings that I need for the F1-F5 keys. In xterm session these bindings work, however when I connect via telnet to the Universe sessions, they don't. For F1 I get ^[OP. I need EX and return. F2 I need + and return and so forth. I have been trawling the net with not much luck. Indications are it's to to do with the terminal settings rather than on the host side however I can't seem to find anything concrete. I found that the the backspace button did not work(even though worked in terminal session) and used a script I found on this forum to run with the telnet command. This tends to suggest that the terminal keyboard mappings need to change for Telnet sessions. The supplier has set up the universe platform for us to test but only have 10 days before it expires. Hope I can get some help before then

I am trying to test a server that is working normal in web browser, with openssl s_client option, connecting it directly using openssl returns the 400 Bad Request: openssl s_client -servername example.com -connect example.com:443 -tls1 (some information about the certificate) GET / HTTP/1.1 (and the error occurs **immediately** - no time to include more headers like Host:) Important: I already tried to put the Host: header, the thing is that when i run GET, the error occur immediately leaving me no chance to include more headers. Replace example.com with my host...