Telnet connections are getting refused after 64, system wide.
This message is filling up /var/log/messages.
systemd: telnet.socket: Too many incoming connections (64)
How do I increase it from the default 64?
Set the new limit in the telnet.socket file.
Add the line: MaxConnections=2048 under [Socket].
/lib/systemd/system/telnet.socket
[Socket]
ListenStream=23
Accept=true
MaxConnections=2048
Restart the telnet daemon with:
systemctl daemon-reload
Related
I used to have an ssh reverse port forwarding from my local computer to a remote EC2 AWS server on port 9999. (9999 for both machines.)
It used to work, but I created a new instance, and now it doesn't anymore. (Half working.) I'm not sure what I did to make it work back then... (Or something was changed.)
I have a process running on my computer on port 9999 and I want it to listen to the port 9999 of my EC2.
On my computer, curl "127.0.0.1:9999" is working.
But I want the code curl "ec2-xx-xx-xx-xx-xx.compute.amazonaws.com:9999" to work, for now it doesn't, giving me the error curl: (7) Failed to connect to ec2-xx-xx-xx-xx-xx.compute.amazonaws.com port 9999 after 59 ms: Connection refused
EC2 Security group is set to open 9999 on TCP for 0.0.0.0/0.
I create the forwarded port with the command :
ssh -R 9999:localhost:9999 -i "/home/example/XXX.pem" ubuntu#ec2-xx-xx-xx-xx-xx.compute.amazonaws.com
The connection ssh is established without errors.
Inside this ssh session I can even do curl "127.0.0.1:9999" inside and IT IS WORKING. Reaching my local computer.
But the request from the web isn't... (curl "ec2-xx-xx-xx-xx-xx.compute.amazonaws.com:9999" doesn't work...)
The path is good, if I install apache2 on port 80 curl "ec2-xx-xx-xx-xx-xx.compute.amazonaws.com:80" is working. (port 80 is added the same way to the security group)
I did sudo ufw disable, same problem.
Do you have an idea what I'm missing ?
EDIT : On the ssh -R forward session on the EC2 :
ubuntu#awsserver:~$ php -S 0.0.0.0:9999 -t .
[Wed Dec 14 16:35:11 2022] Failed to listen on 0.0.0.0:9999 (reason: Address already in use)
BUT, if I open a normal ssh session, I can run php -S 0.0.0.0:9999 -t ., the code curl "ec2-xx-xx-xx-xx-xx.compute.amazonaws.com:9999" is working everywhere as expected.
So... it is telling me that the port is already used (By the ssh -R command), but is closed when I try to connect to it... I don't get it.
The answer wasn't EC2/AWS related.
It's a security feature from SSH that I had to disable : GatewayPorts yes
On a CentOS Linux 7 machine, I have a web app served on port 1314
$ netstat -anp | grep 1314
tcp 0 0 127.0.0.1:1314 0.0.0.0:* LISTEN 1464/hugo
tcp 0 0 127.0.0.1:60770 127.0.0.1:1314 TIME_WAIT -
and I can curl it locally.
I opened port 1314:
iptables-save | grep 1314
-A IN_public_allow -p tcp -m tcp --dport 1314 -m conntrack --ctstate NEW,UNTRACKED -j ACCEPT
I checked with nmap locally:
PORT STATE SERVICE
1314/tcp open pdps
Everything seems fine.
Now if I try to curl the web app from another machine I get connection refused.
When I try nmap from the remote machine:
PORT STATE SERVICE
1314/tcp closed pdps
So the firewall doesn't block the port, but it looks like there is no one listening on port 1314...
But we know that the web app is running on this endpoint so what is going on??
Having a process listening to a port (and that port is open and properly configured) is not enough to enable remote communication. The local address needs to be on the same network as the remote address too!
Here, on the netstat printout, we can see that the local address is localhost (127.0.0.1 or ::1). Localhost is obviously not on the same network as the remote machine I was using to curl my web app. This explains also why nmap was reporting a closed port (meaning that nothing was listening on the local end).
Note: to listen to all the network interfaces, the local address should be 0.0.0.0 or :::.
This is the error when trying to run icecast2 from the serving using the terminal (command line): sudo icecast2 -b -c /etc/icecast2/icecast.xml
Error message:
EROR connection/connection_setup_sockets Could not create listener socket on
port 8000
EROR connection/connection_setup_sockets No listening sockets established
Server startup failed. Exiting
I can load the icecast server from browser BUT no mount points. Please help.
Sounds like Icecast is already running.
Why are you trying to start it manually? You should use systemd or the init script that comes with the Icecast package of your distribution.
I am using a digitalocean ubuntu 14.04 vps. When I run
sudo lsof -i:9000
I get varying results such as
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
gunicorn 23148 django 5u IPv4 51019 0t0 TCP localhost:9000 (LISTEN)
or
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
gunicorn 23174 django 5u IPv4 51179 0t0 TCP localhost:9000 (LISTEN)
gunicorn 23175 django 5u IPv4 51179 0t0 TCP localhost:9000 (LISTEN)
where the number of gunicorn processes varies from 0-4, even if I run lsof immediately after the previous attempt. Simply running
pkill gunicorn
is failing, I believe because the PIDs are constantly changing (as shown above). How can I kill these processes permanently? If it makes a difference, I am user "root", and do not have a login for user "django"
lsof will only show the child processes which are actually binding to the port. You need to kill the master process. If you start gunicorn with the --pid option you can give it a filename to store the PID of that process in, then you can kill it directly; if not you can get it from ps|grep gunicorn.
Even better, as elethan suggests in the comments, set up gunicorn as a service using whatever process manager exists on your system - systemd, upstart, supervisor, or whatever - and use that to start and stop it.
I'm running OS X Mountain Lion on a machine with local IP address 192.168.1.6 (as reported by both the Network utility and ifconfig) and am running a local (Django) development web server on port 8000 that I would like to connect to from a virtual machine running a guest OS on the same machine.
On the host OS (ie, OS X running on the metal of the machine w/ address 192.168.1.6) I can connect to my test web server through the browser by navigating to 127.0.0.1:8000; or localhost:8000; but not when using the machine's local IP address. Here's what makes this extra confusing:
The router is not filtering the ports; and, just to be sure, I've set it to explicitly forward ports 8000 and 22 to 192.168.1.6; And speaking of port 22,
When I start the SSH service, I can connect (from the command line) via ssh 192.168.1.6
It's not a browser issue, because I also can't telnet to 192.168.1.6 port 8000 (connection refused) while I can telnet to 127.0.0.1 port 8000, and I can also telnet to 192.168.1.6 port 22
The firewall is set to off (as reported in System Preferences) but to be extra safe, I've also set an ipfw rule to allow everything through
Here are the ipfw rules:
00100 allow tcp from any to any dst-port 8000
65535 allow ip from any to any
Here is additional confirmation that the port is, indeed, being listened to by my test server:
netstat -an | grep 8000
tcp4 0 0 127.0.0.1.8000 *.* LISTEN
so what's going on here? Somehow port 22 is being treated differently than port 8000, but every place I can think to look for those differences I can't find any. Why can't I get into this machine's port 8000 using its local ip address?
When you start Django development server you need to give the address explicitly:
python manage.py runserver 192.168.1.6:8000
Or if you want the server to run on all interfaces you can use:
python manage.py runserver 0.0.0.0:8000
In other case Django development server defaults to running on the local interface only.
The problem for me was I accidentally quit the server whenever trying to copy the server address. So instead of using ctrl+C just write down the address into your browser.
I solved the issue.There are a few things you might be missing.Listing them below-
1.Once it starts the server, do not press Ctrl+C anyhow .u might be pressing it to copy to url and that accidently closes the server due to which it might be happening.
2.instead of http://127.0.0.1:8000/ ...change the port number to http://127.0.0.1:8080/ ...That would work.
3.Try changing the firewall setting and allow the app.
4.Try opening it with different browsers and incognito too.
The above steps helped solve my issue.Hope they help u too...:)