I am trying to connect to one of our staging Cassandra servers on port 9042 and 9160 here in our company from a dev box.. Through the code, I am not able to connect to it... The program gets hanged at my SELECT query..
So I am wondering is there any way to figure out from my dev box whether these two ports are either blocked on my Cassandra staging servers or not?
Below is the Cassandra staging server url which I am trying to connect from my dev box -
sc-host01.vip.slc.qa.host.com
And my dev box machine url is -
username-dyn-vm1-4.phx-os1.tratus.dev.host.com
Can anyone tell me how to figure out what can be the possible reason to which I am not able to connect to it..
How to check from my dev box whether these ports are opened or not on my Cassandra staging servers?
Update:-
ubuntu#username-dyn-vm1-4:~/build$ traceroute sc-host01.vip.slc.qa.host.com
traceroute to sc-host01.vip.slc.qa.host.com (10.109.107.64), 30 hops max, 60 byte packets
1 10.9.209.1 (10.9.209.1) 4.594 ms 6.628 ms 8.299 ms
2 * * *
3 * * *
4 * * *
5 * * *
6 * * *
7 stgcass01-1.vip.slc.qa.host.com (10.109.107.64) 7.907 ms 3.312 ms 3.950 ms
This is what I got when I ran nmap -
ubuntu#username-dyn-vm1-4:~/build$ nmap -p T:9160 sc-host01.vip.slc.qa.host.com
Starting Nmap 6.00 ( http://nmap.org ) at 2013-10-13 20:01 UTC
Nmap scan report for sc-host01.vip.slc.qa.host.com (10.109.107.64)
Host is up (0.0037s latency).
rDNS record for 10.109.107.64: stgcass01-1.vip.slc.qa.host.com
PORT STATE SERVICE
9160/tcp open apani1
Nmap done: 1 IP address (1 host up) scanned in 0.19 seconds
ubuntu#username-dyn-vm1-48493:~/build$ nmap -p T:9042 sc-host01.vip.slc.qa.host.com
Starting Nmap 6.00 ( http://nmap.org ) at 2013-10-13 20:02 UTC
Nmap scan report for sc-host01.vip.slc.qa.host.com (10.109.107.64)
Host is up (0.0049s latency).
rDNS record for 10.109.107.64: stgcass01-1.vip.slc.qa.host.com
PORT STATE SERVICE
9042/tcp open unknown
Nmap done: 1 IP address (1 host up) scanned in 0.11 seconds
Does that mean port is opened correctly and there is no problem?
And with telnet I get this -
ubuntu#username-dyn-vm1-4:~/build$ telnet sc-host01.vip.slc.qa.host.com 9042
Trying 10.109.107.64...
Connected to stgcass01-1.vip.slc.qa.host.com.
Escape character is '^]'.
^CConnection closed by foreign host.
ubuntu#username-dyn-vm1-4:~/build$ telnet sc-host01.vip.slc.qa.host.com 9160
Trying 10.109.107.64...
Connected to stgcass01-1.vip.slc.qa.host.com.
Have you tried telnet from the dev box?
telnet sc-host01.vip.slc.qa.host.com 9042
telnet sc-host01.vip.slc.qa.host.com 9160
if you get a telnet prompt back, you have connectivity, if it hangs there the connection may be timing out, if the command fails outright you may have firewall rules preventing access. You can try 'traceroute sc-host01.vip.slc.qa.host.com' to see the path the connection is trying to take.
Related
I have a simple program which creates a simple web server at localhost with a random port between 10000 and 65535 (which is the highest unsigned 16-bit integer). You can also specify a port but if you don't know on which port it runs it's hard to find out.
I have written a little helper program that should show every port that's being listened to.
The helper:
import requests
for port in range(10000, 65535):
try:
print(port, requests.get("http://localhost:{}".format(port)))
except Exception as e:
print("{}: {}".format(type(e).__name__, port), end="\r")
I expect it to show ConnectionError: 10000 and counting up to 65535 and showing any found connections. But it hangs always on port 25564 25565, last showing the message for port 25564. And if I do a completely unrelated request to 'http://localhost:25564' or any higher port it hangs.
The script hangs on port 25565 when I start a server on 25564.
Normally if a port has no server listening it will immediately refuse the connection and give a ConnectionError. Above port 25564 it doesn't but just waits until I stop it.
This behaviour seems completely random as port 25564 is unassigned according to speedguide.net.
Port 25565 is the standard MySQL and Minecraft Dedicated Server port (according to speedguide.net), both of which I haven't running on my machine. Therefore the hang still seems random.
I'm using python3 on Ubuntu 20.04 LTS.
Interestingly it didn't fail on my laptop with Linux Mint 21...
As #root requested in the comments, here is the output of nmap localhost:
Starting Nmap 7.80 ( https://nmap.org ) at 2022-09-25 11:42 CEST
Host is up (0.00014s latency).
Not shown: 996 closed ports
PORT STATE SERVICE
80/tcp open http
631/tcp open ipp
8080/tcp open http-proxy
9050/tcp open tor-socks
Nmap done: 1 IP address (1 host up) scanned in 0.06 seconds
Just a little note: port 80/tcp is listened on by apache2 with the "You are an idiot" flash animation.
As per the comments, you can try something like this:
You will note that i have added the timeout parameter in the requests. This units are in seconds. The default timeout is None, which means it'll wait (hang) until the connection is closed.
import requests
for port in range(10_000, 65_535):
try:
r = requests.get(f'http://localhost:{port}', timeout=5)
print(port)
except Exception as e:
print(f'{type(e).__name__}, {port}', end='\r')
For my own sanity, does anyone know why rpcbind (linux) is opening a seemingly random port every time it's restarted? I know it uses port 111, but what is this other port that keeps opening up with it? Thanks.
[root#testmachine ~]# nmap -sU -p 0-65535 127.0.0.1
Starting Nmap 5.51 ( http://nmap.org ) at 2016-03-03 16:00 EST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000080s latency).
Not shown: 65533 closed ports
PORT STATE SERVICE
111/udp open|filtered rpcbind
819/udp open|filtered unknown
Nmap done: 1 IP address (1 host up) scanned in 3.11 seconds
[root#testmachine ~]# service rpcbind restart
Stopping rpcbind: [ OK ]
Starting rpcbind: [ OK ]
[root#testmachine ~]# nmap -sU -p 0-65535 127.0.0.1
Starting Nmap 5.51 ( http://nmap.org ) at 2016-03-03 16:00 EST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000080s latency).
Not shown: 65533 closed ports
PORT STATE SERVICE
111/udp open|filtered rpcbind
846/udp open|filtered unknown
Nmap done: 1 IP address (1 host up) scanned in 2.97 seconds
[root#testmachine ~]# service rpcbind restart
Stopping rpcbind: [ OK ]
Starting rpcbind: [ OK ]
[root#testmachine ~]# nmap -sU -p 0-65535 127.0.0.1
Starting Nmap 5.51 ( http://nmap.org ) at 2016-03-03 16:05 EST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.0000070s latency).
Not shown: 65533 closed ports
PORT STATE SERVICE
111/udp open|filtered rpcbind
892/udp open|filtered unknown
Nmap done: 1 IP address (1 host up) scanned in 2.86 seconds
More than likely, it's an RPC service. Try the rpcinfo command to see what it is.
Unlike most other network services (FTP, HTTP, SMTP, etc), RPC services are bound to dynamic ports. Instead of connecting directly to the server, an RPC client first sends a request to the RPC port mapper (UDP/111 by default) to find out what port the server is on (a similar is used on Windows).
On a related note, nmap is great, but there are much easier ways to learn about the listening ports on your computer. Try this instead: sudo netstat -anp | grep LISTEN. It's much faster and will even give you the process name and number.
Also, nmap 5.51 is about five years old now. If you use it often, it's worth upgrading to get some new features.
The Debian man page for rpcbind tells me that:
All RPC servers must be restarted if rpcbind is restarted.
The OP didn't mention that they'd done that, so how would any of the RPC services have reregistered? Imagine my surprise, then, on repeating the OP's experiment and applying the rpcinfo -p suggestion from #SArcher to see that all the RPC services were still registered... and on their original ports, suggesting that #SArcher wasn't quite on the money.
If, however, we also apply the other great suggestion from #SArcher, namely to sudo netstat -anp, we get something more interesting. Now we can't |grep LISTEN as suggested because the OP's post says udp and UDP sockets are never in state LISTEN. What we do find is that rpcbind doesn't just have sockets on port 111 - its job - but also another "reserved" port picked seemingly at random when rpcbind starts, just as the OP says.
So "what is this other port for?" you ask. Sorry to tease but I just answered that in my description of:
Debian bug 870579: rpcbind callit replies from a random reserved udp port, making firewalling hard
On redhat there is a separate service called rpcbind.socket. This gets started with rpcbind.service. rpcbind.service first checks if port 111 is available, if it is not available then it chooses a port and starts listening on that port.
In redhat the rpcbind.socket is started first and it startes using port 111. In netstat the port 111 will be displayed as used by systemd. When rpcbind is started it finds that port 111 is already used by systemd and hence it chooses a different port. If you mask the rpcbind.socket service and then start rpcbind.service, rpcbind will start listening on port 111.
I have a:
Rasberry Pi 2
running
Raspbian Jessie Version:November 2015
I am using Undertow (a Java http server) to serve a website. This is the code that I use to build the server.
Undertow server = Undertow.builder()
.addHttpListener(8890, "localhost")
.setHandler(Handlers.pathTemplate()
.add("/", resource(new PathResourceManager(staticFilePath, 100))
.setDirectoryListingEnabled(false))
.build();
Problem: I am unable to see the webserver from another machine on the local network despite being able to ping and SSH into the PI.
What I have done (on the Pi2):
wget localhost:8890
returns the index.html correctly
netstat -lptn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN -
tcp6 0 0 :::22 :::* LISTEN -
tcp6 0 0 127.0.0.1:8890 :::* LISTEN 1743/java
Chrome on my development machine 192.168.1.8:8890 gives
ERR_CONNECTION_REFUSED
wget 192.168.1.8:8890
Connecting to 192.168.1.8:8890... failed: Connection refused.
nmap 192.168.1.8
Starting Nmap 6.40 ( http://nmap.org ) at 2015-12-05 14:05 CST
Nmap scan report for 192.168.1.8
Host is up (0.039s latency).
Not shown: 999 closed ports
PORT STATE SERVICE
22/tcp open ssh
Nmap done: 1 IP address (1 host up) scanned in 1.83 seconds
It is my understanding that there is no firewall so I am baffled as to why I can't see the server from my development machine.
See:
tcp6 0 0 127.0.0.1:8890 :::* LISTEN 1743/java
Your web server listens only on localhost address (127.0.0.1). This way it couldn't be accessed from anywhere but localhost.
And your nmap scan shows the same: the only remotely accessible port is 22.
To access this service remotely you have to bind web server to any non-local address belonging to this raspberry pi (192.168.1.8) or to "any address" 0.0.0.0, as SSH service is bound.
How to do this is written in the manual of your web server. Probably, you have to start is with a "-d" param, i.e.
standalone.sh -b=0.0.0.0
standalone.sh -Djboss.bind.address=0.0.0.0
or something like this.
In listener setup code this looks like
"localhost" have to be replaced with some public name. This could be "0.0.0.0" or "192.168.1.8". We also can
cat "192.168.1.8 somename" >> /etc/hosts
and then use somename:
Undertow server = Undertow.builder() .addHttpListener(8890, "somename")
I have a process that I'm running on my local machine which is listening on TCP port 9000. I would like to consume on another computer of my network. Here is my configuration:
I would like to see it when I run nmap 10.18.12.12 but I don't know how.
nmap localhost
Starting Nmap 6.47 ( http://nmap.org ) at 2015-08-20 13:49 ART
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00037s latency).
Other addresses for localhost (not scanned): 127.0.0.1
Not shown: 987 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
80/tcp open http
111/tcp open rpcbind
443/tcp open https
631/tcp open ipp
3306/tcp open mysql
5432/tcp open postgresql
8000/tcp open http-alt
**9000/tcp open cslistener**
9001/tcp open tor-orport
9999/tcp open abyss
Starting Nmap 6.47 ( http://nmap.org ) at 2015-08-20 13:45 ART
Nmap scan report for 10.18.12.12
Host is up (0.00073s latency).
Not shown: 994 closed ports
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
80/tcp open http
111/tcp open rpcbind
443/tcp open https
3306/tcp open mysql
The service is bound to 127.0.0.1. You can see this without using Nmap; use netstat instead: netstat -tln will show all listening TCP ports. You should see something like this:
$ netstat -tln
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:9000 0.0.0.0:* LISTEN
In this example, the service on port 21 (FTP) is listening on the special address 0.0.0.0 which means "any available address," but the service on port 9000 is bound to 127.0.0.1, which is a special address ("localhost" or "loopback") not accessible from the network.
Most services will have a way to specify which addresses or interfaces to listen on. Read the manual for the service you are interested in to determine how to change this.
I have a vm in vmware workstation, it's bridged network and DHCP. The IP assigned by DHCP server is 10.21.245.22. Here is my /etc/hosts looks like:
127.0.0.1 hadoop-namenode-01 localhost
I am running command A and B on the box itself.
Command A:
root#hadoop-namenode-01:~# nmap -sT -sU -p- localhost
Starting Nmap 5.21 ( http://nmap.org ) at 2012-08-10 09:32 PDT
Nmap scan report for localhost (127.0.0.1)
Host is up (0.00029s latency).
rDNS record for 127.0.0.1: hadoop-namenode-01
Not shown: 131058 closed ports
PORT STATE SERVICE
22/tcp open ssh
53/tcp open domain
631/tcp open ipp
8020/tcp open unknown
9000/tcp open cslistener
9001/tcp open tor-orport
50070/tcp open unknown
53/udp open|filtered domain
68/udp open|filtered dhcpc
123/udp open ntp
5353/udp open|filtered zeroconf
47982/udp open|filtered unknown
Nmap done: 1 IP address (1 host up) scanned in 12.45 seconds
Command B:
root#hadoop-namenode-01:~# nmap -sT -sU -p- 10.21.245.22
Starting Nmap 5.21 ( http://nmap.org ) at 2012-08-10 09:28 PDT
Nmap scan report for wn7x64-3jql0q1.dub.emea.dell.com (10.21.245.22)
Host is up (0.00029s latency).
Not shown: 131065 closed ports
PORT STATE SERVICE
22/tcp open ssh
68/udp open|filtered dhcpc
123/udp open ntp
5353/udp open|filtered zeroconf
47982/udp open|filtered unknown
Nmap done: 1 IP address (1 host up) scanned in 12.20 seconds
My question is :
since I have no firewall or anything like that blocking ports, why nmap shows more ports open when it's running against localhost while less ports are shown when it's running against the ip.
why nmap shows more ports open when it's running against localhost
while less ports are shown when it's running against the ip
Some applications decided to explicitly listen (bind actually) only on localhost, i.e. 127.0.0.1. You can do a netstat to check things out.
Most of system running process in Linux use loopback (127.0.0.1) ip address to communicate with each other. It doesn't require to send packet outside network.