I have an autossh tunnel set up over which I am sending something that needs an uninterrupted connection for a couple dozen minutes. However, I noticed that every 10 minutes the SSH tunnel managed by autossh is killed and recreated.
This is not due to an inactive connection, as there is active communication happening through that channel.
The command used to set up the tunnel was:
autossh -C -f -M 9910 -N -L 6969:127.0.0.1:12345 remoteuser#example.com
In my case the problem was a clash of the monitoring ports on the remote server. There are multiple servers all autossh-ing to the single central server and two of those "clients" used the same monitoring port (-M).
The default interval in which autossh tries to communicate over the monitoring channel is 600 seconds, 10 minutes. When autossh starts up, it does not verify that it could open the remote monitoring port. Everything will look fine until the time when autossh tries to check that the connection is open - and it fails. At that point the SSH tunnel will be forcibly killed and recreated.
A good way to check if this is your case as well is change the default timeout using the AUTOSSH_POLL environment variable:
AUTOSSH_POLL=10 autossh -C -f -M 9910 -N -L 6969:127.0.0.1:12345 remoteuser#example.com
Related
After I changed router, there is a delay in rsync that i could not trace even with high verbosity output settings for logs. I am running an rsync daemon on an android device (Wifi connected to router). I copy files from that device to another device (LAN connected to router). The delay can be seen even on "--list-only" option. Things are working very well for about 2 years already before I changed our router. The log is shown below:
rsync -vvvvvvvvvv --stats --progress --list-only --port xxxx xxx#xxx.xxx.xxx.xxx::share/
FILE_STRUCT_LEN=16, EXTRA_LEN=4
opening tcp connection to xxx.xxx.xxx.xxx port xxxx
Connected to xxx.xxx.xxx.xxx (xxx.xxx.xxx.xxx)
msg checking charset: UTF-8
There is a delay of atleast 8 seconds after that initial connection. This is the problem. After this delay, everything goes smoothly. Everything is fast.
sending daemon args: --server --sender -vvvvvvvvvvde.Lsfx --list-only . share/ (6 args)
(Client) Protocol versions: remote=30, negotiated=30
receiving file list ...
recv_file_name(.)
recv_file_name(xxxx)
....
....
I can confirm it only occurs in the new router because the delay disappears when I connect the old one. My new router is TL WR841N. I have tried disabling all security features in it (flooding protection, etc) except the usual WPA2-AES password for the access point. I could not trace what rsync is trying to do when the delay occurs.
Although the delay is just in the beginning, my current backup methods include starting rsync many times. Thus if I start rsync 10 times, there is already an overhead of 8*10 seconds for starting delay, which did not exist with my previous router.
I have tried researching already, but the problems of others I have found are not very relevant to the delay I am experiencing (most have problems on SSH, but I am running an rsync daemon, not rsync on SSH)
How can I trace the problem? Any idea for the delay?
I want to make a backup for my remote server folders(ubunto server)to another remote sever (Linux server). but once I run this command from the the first server it dispalys me an error message:
rsync -raz --progress firstdirectoy root#serverIP:/home
The displayed messahe is:
ssh: connect to host <serverIP> port 22: Connection timed out
rsync: connection unexpectedly closed (0 bytes received so far) [sender]
rsync error: unexplained error (code 255) at io.c(601) [sender=3.0.7]
But the same command from the server 2 to the server 1 works fine and the folder is nicely copyed into the server1.
How can I escape the connexion error in order to copy my folder from server 1 to server 2 throw rsync?
Seems like server2 has no active ssh daemon while server1 has.
Try to run ssh daemon or use raw rsync protocol and rsync daemon.
If it's a connection timeout because your SSH server is slow to respond, you can tweak the timeout in rsync:
rsync -e 'ssh -o ConnectTimeout=120'
Else it may be a missing SSH daemon (sshd) on server 2 as stated by #geov, or a closed port on your firewall. You may start by testing an SSH login:
ssh user#serverIP
And see if it's working or not. Probably nmap serverIP will help you too, stating if SSH is running or not.
And please do NOT use root user for your rsync copy!
if you wait for a long time, the prompt appears
I think that your server2's IP is wrong
For me, this error appeared when attempting to rsync between two AWS EC2 instances where the two instances were not a part of the same security group.
Overview of how to create security groups
How to change the security groups of the instances
Allow instances within the same security group to communicate
Environment:
Unix client and unix server.
Tool used : curl.
Client/Server should ignore the time wait time (2 *MSL ) when establishing connection.
This is done by executing the following commands :
sysctl net.ipv4.tcp_tw_reuse=1
sysctl net.ipv4.tcp_tw_recycle=1
Local port must be specified so that it can re-used.
Start the connection.
Example : while [ 1 ]; do curl --local-port 9056 192.168.40.2; sleep 30; done
I am still seeing the error even though it should have ignored time wait period.
Any idea why this is happening?
OK, we all know how to use PING to test connectivity to an IP address. What I need to do is something similar but test if my outbound request to a given IP Address as well as a specif port (in the present case 1775) is successful. The test should be performed preferably from the command prompt.
Here is a small site I made allowing to test any outgoing port. The server listens on all TCP ports available.
http://portquiz.net
telnet portquiz.net XXXX
If there is a server running on the target IP/port, you could use Telnet. Any response other than "can't connect" would indicate that you were able to connect.
To automate the awesome service portquiz.net, I did write a bash script :
NB_CONNECTION=10
PORT_START=1
PORT_END=1000
for (( i=$PORT_START; i<=$PORT_END; i=i+NB_CONNECTION ))
do
iEnd=$((i + NB_CONNECTION))
for (( j=$i; j<$iEnd; j++ ))
do
#(curl --connect-timeout 1 "portquiz.net:$j" &> /dev/null && echo "> $j") &
(nc -w 1 -z portquiz.net "$j" &> /dev/null && echo "> $j") &
done
wait
done
If you're testing TCP/IP, a cheap way to test remote addr/port is to telnet to it and see if it connects. For protocols like HTTP (port 80), you can even type HTTP commands and get HTTP responses.
eg
Command IP Port
Telnet 192.168.1.1 80
The fastest / most efficient way I found to to this is with nmap and portquiz.net described here: http://thomasmullaly.com/2013/04/13/outgoing-port-tester/ This scans to top 1000 most used ports:
# nmap -Pn --top-ports 1000 portquiz.net
Starting Nmap 6.40 ( http://nmap.org ) at 2017-08-02 22:28 CDT
Nmap scan report for portquiz.net (178.33.250.62)
Host is up (0.072s latency).
rDNS record for 178.33.250.62: electron.positon.org
Not shown: 996 closed ports
PORT STATE SERVICE
53/tcp open domain
80/tcp open http
443/tcp open https
8080/tcp open http-proxy
Nmap done: 1 IP address (1 host up) scanned in 4.78 seconds
To scan them all (took 6 sec instead of 5):
# nmap -Pn -p1-65535 portquiz.net
The bash script example of #benjarobin for testing a sequence of ports did not work for me so I created this minimal not-really-one-line (command-line) example which writes the output of the open ports from a sequence of 1-65535 (all applicable communication ports) to a local file and suppresses all other output:
for p in $(seq 1 65535); do curl -s --connect-timeout 1 portquiz.net:$p >> ports.txt; done
Unfortunately, this takes 18.2 hours to run, because the minimum amount of connection timeout allowed integer seconds by my older version of curl is 1. If you have a curl version >=7.32.0 (type "curl -V"), you might try smaller decimal values, depending on how fast you can connect to the service. Or try a smaller port range to minimise the duration.
Furthermore, it will append to the output file ports.txt so if run multiple times, you might want to remove the file first.
I've got a remote server on eapps.com that I'm using as my "production" server. I have my own computer at home that I'm using as my "development" server. I'm trying to use JNDI over HTTP to do some batch processing. The following works at home, but not on the eapps machine.
I'm connecting to some EJBs (stateless session), and have my jndi.properties set to this:
(this is for the eapps machine)
java.naming.factory.initial=org.jboss.naming.HttpNamingContextFactory
java.naming.provider.url=http://my.prodhost.com:8080/invoker/JNDIFactory
java.naming.factory.url.pkgs=org.jboss.naming.client:org.jnp.interfaces
# timeout is in milliseconds
jnp.timeout=15000
jnp.sotimeout=15000
jnp.maxRetries=3
(this is for my machine at home)
java.naming.factory.initial=org.jboss.naming.HttpNamingContextFactory
java.naming.provider.url=http://localhost:8080/invoker/JNDIFactory
java.naming.factory.url.pkgs=org.jnp.interfaces
java.naming.factory.url.pkgs=org.jboss.naming.client
# timeout is in milliseconds
jnp.timeout=15000
jnp.sotimeout=15000
jnp.maxRetries=3
As I said, it works at home, but when I try it remotely, I get:
Can not get connection to server. Problem establishing socket connection for InvokerLocator [socket://my.prodhost.com:4446//?dataType=invocation&enableTcpNoDelay=true&marshaller=org.jboss.invocation.unified.marshall.InvocationMarshaller&socketTimeout=600000&unmarshaller=org.jboss.invocation.unified.marshall.InvocationUnMarshaller]
...
Caused by: java.net.ConnectException: Connection timed out: connect
Am I doing something wrong here, or is it possibly a firewall issue? To the best of my knowledge, port 4446 is not blocked.
Are the differences in the jndi.properties intentional (at the java.naming.factory.url.pkgs property level)?
Also, can you run a netstat -a | grep 4446 on both machines and update the question with the output?
Update: If the netstat command didn't return anything for port 4446 (JBoss was running, right?), then the JBoss Remoting Connector for the UnifiedInvoker service is very likely not listening on your eApps host, hence the connection timeout. Maybe this service has been disabled by eApps, you should contact the support and discuss this with them.
Just in case, a sample Connector configuration can be found in the jboss-service.xml under the server node's conf directory. Maybe compare the remote one (if you have access to it) with your local file to confirm this (but if it's disable, there must be a reason, discuss it with the support).
And by the way, this is what I get when I run the netstat command with JBoss 4.2.3.GA started on my GNU/Linux machine (default configuration):
$ netstat -a | grep 4446
tcp 0 0 localhost:4446 *:* LISTEN