I'm trying to debug a new server I ordered at OVH.com and they insist everything is working properly even though it times out when doing a curl request towards for an example github.com (times out 9 in around 10 tries)
curl -L -v https://github.com
I get
* Rebuilt URL to: https://github.com/
* Trying 140.82.118.4...
* connect to 140.82.118.4 port 443 failed: Connection timed out
* Failed to connect to github.com port 443: Connection timed out
* Closing connection 0
curl: (7) Failed to connect to github.com port 443: Connection timed out
Even when I set up NGINX sever, site timeouts almost every second request
So I thought perhaps DHCP server can be an issue so I checked it and I see this from (var/lib/dhcp..)
lease {
interface "ens4";
fixed-address 10.0.X.XX;
option subnet-mask 255.255.255.0;
option routers 10.0.X.X;
option dhcp-lease-time 86400;
option dhcp-message-type 5;
option dhcp-server-identifier 10.0.X.X;
option domain-name-servers 10.0.X.X;
renew 6 2020/03/28 02:16:19;
rebind 6 2020/03/28 13:47:57;
expire 6 2020/03/28 16:47:57;
}
lease {
interface "ens4";
fixed-address 10.0.X.XX;
option subnet-mask 255.255.255.0;
option routers 10.0.X.X;
option dhcp-lease-time 86400;
option dhcp-message-type 5;
option dhcp-server-identifier 10.0.X.X;
option domain-name-servers 10.0.X.X;
renew 5 2020/03/27 16:51:54;
rebind 5 2020/03/27 16:51:54;
expire 5 2020/03/27 16:51:54;
}
I tried getting a new one by doing this command but nothing changes, still the same as above
sudo dhclient -r
Am I looking at the DHCP wrong or does it look normal? For the record my public IP on this dedicated starts with 5 not 1 and it is run on Ubuntu 16.04 LTS
What is the offer you have at OVH ? They usually don't give private IP to dedicated server or virtual private server, so that's quite odd.
You may want to collect some trace to check what is going wrong with tools like :
tcptraceroute to check if the path to a domain on port 80 or 443
looks strange
ping to be able to see if there packet loss
tcpdump to capture raw network packet while a timeout is occuring to see what's going on
That's a good start and may also help you go back to OVH Support and prove them there's something wrong.
Related
Is there is a way to check if localhost is making ftp connection to other server?
The requirement is like this: Local host -> serverA
Remote server --> serverB.
Need to check if serverA is making ftp connection to serverB.
So whenever serverA is making ftp connection to serverB, how to get notified.
I tried like this: ps -ef | grep -i ftp; however since ps process too would get notified, so can't make this use in shell script, is there any better way which checks if serverA is making ftp connections to serverB, and if so, get notified / logs to a file.
Thanks
Your problem of "ps -ef | grep -i ftp" also reporting the 'ps' process is resulting from grep searching the string "ftp". This would also hit a lot of other processes which also have the word 'ftp' in it's command line.
To fix that check if you have the procps tools "pgrep" and "pkill" installed. They are very helpful for 'grepping' processes and running commandlines.
To solve your initial problem you might check if you have the 'ss' (show sockets from iproute2 packages) command installed.
It's output might be useful (11.22.33.44 is you local IP 130.133.3.130 the remote):
root:sigkill:~/# ss -p|cat
State Recv-Q Send-Q Local Address:Port Peer Address:Port
[...]
ESTAB 0 0 11.22.33.44:43681 130.133.3.130:ftp users:(("ftp",19729,4),("ftp",19729,3))
[...]
There are a few approaches that you could take:
You could poll running processes for ftp. This wouldn't catch other FTP clients (if you care about that), and it wouldn't catch very short ftp sessions that slip between polls.
If your system supports execution logging, you could log all executions of ftp. Again, this wouldn't catch other FTP clients.
You could watch for outbound connections on port 21/tcp using some mechanism provided by your system (for instance, on Linux, use an iptables rule that matches outbound FTP connections to any servers that you care about and logs them using the LOG target). This would catch all connections regardless of client, but tracking down the process and user would be a little more complicated.
You can use $ grep ftp /etc/services to list the current ftp connections.
$ grep ftp /etc/services
ftp-data 20/tcp
ftp-data 20/udp
...
ftp 21/tcp
ftp 21/udp fsp fspd
...
sftp 115/tcp
sftp 115/udp
...
ftp-data 20/sctp # FTP
ftp 21/sctp # FTP
...
ftps-data 989/tcp # ftp protocol, data, over TLS/SSL
ftps-data 989/udp # ftp protocol, data, over TLS/SSL
ftps 990/tcp # ftp protocol, control, over TLS/SSL
ftps 990/udp # ftp protocol, control, over TLS/SSL
Use netstat to see the open connections. e.g., For simple FTP...
$ netstat -tan | grep \:21
tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN
tcp 0 0 :::21 :::* LISTEN
I'm trying to write the linux client script for a simple port knocking setup. My server has iptables configured to require a certain sequence of TCP SYN's to certain ports for opening up access. I'm able to successfully knock using telnet or manually invoking netcat (Ctrl-C right after running the command), but failing to build an automated knock script.
My attempt at an automated port knocking script consists simply of "nc -w 1 x.x.x.x 1234" commands, which connect to x.x.x.x port 1234 and timeout after one second. The problem, however, seems to be the kernel(?) doing automated SYN retries. Most of the time more than one SYN is being send during the 1 second nc tries to connect. I've checked this with tcpdump.
So, does anyone know how to prevent the SYN retries and make netcat simply send only one SYN per connection/knock attempt? Other solutions which do the job are also welcome.
Yeah, I checked that you may use nc too!:
$ nc -z example.net 1000 2000 3000; ssh example.net
The magic comes from (-z: zero-I/O mode)...
You may use nmap for port knocking (SYN). Just exec:
for p in 1000 2000 3000; do
nmap -Pn --max-retries 0 -p $p example.net;
done
try this (as root):
echo 1 > /proc/sys/net/ipv4/tcp_syn_retries
or this:
int sc = 1;
setsockopt(sock, IPPROTO_TCP, TCP_SYNCNT, &sc, sizeof(sc));
You can't prevent the TCP/IP stack from doing what it is expressly designed to do.
I have box A and it has a consumer on it that listens on a Rabbit MQ server
I have box B that will publish a message to the listener
So as long as all of this in on box A and I start Rabbit MQ server w/ defaults it works fine.
The defaults are host=127.0.0.1 on port 5672, but
when I telnet box.a.ip.addy 5672 from box B I get:
Trying box.a.ip.addy...
telnet: connect to address box.a.ip.addy: No route to host
telnet: Unable to connect to remote host: No route to host
telnet on port 22 is fine, I can ssh into Box A from Box B
So I assume I need to change the ip that the RabbitMQ server uses
I found this: http://www.rabbitmq.com/configure.html and I now have a config file in the location the documentation said to use, with the name rabbitmq.config and it contains:
[
{rabbit, [{tcp_listeners, {"box.a.ip.addy", 5672}}]}
].
So I stopped the server, and started RabbitMQ server again. It failed. Here are the errors from the error logs. It's a little over my head. (in fact most of this is)
=ERROR REPORT==== 23-Aug-2011::14:49:36 ===
FAILED
Reason: {{case_clause,{{"box.a.ip.addy",5672}}},
[{rabbit_networking,'-boot_tcp/0-lc$^0/1-0-',1},
{rabbit_networking,boot_tcp,0},
{rabbit_networking,boot,0},
{rabbit,'-run_boot_step/1-lc$^1/1-1-',1},
{rabbit,run_boot_step,1},
{rabbit,'-start/2-lc$^0/1-0-',1},
{rabbit,start,2},
{application_master,start_it_old,4}]}
=INFO REPORT==== 23-Aug-2011::14:49:37 ===
application: rabbit
exited: {bad_return,{{rabbit,start,[normal,[]]},
{'EXIT',{rabbit,failure_during_boot}}}}
type: permanent
and here is some more from the start up log:
Erlang has closed
Error: {node_start_failed,normal}
^M
Crash dump was written to: erl_crash.dump^M
Kernel pid terminated (application_controller) ({application_start_failure,rabbit,{bad_return,{{rabbit,start,[normal,[]]},{'EXIT',{rabbit,failure_during_boot}}}}})^M
Please help
did you try adding?
RABBITMQ_NODE_IP_ADDRESS=box.a.ip.addy
to the /etc/rabbitmq/rabbitmq.conf file?
Per http://www.rabbitmq.com/configure.html#customise-general-unix-environment
Also per this documentation it states that the default is to bind to all interfaces. Perhaps there is a configuration setting or environment variable already set in your system to restrict the server to localhost overriding anything else you do.
UPDATE: After reading again I realize that the telnet should have returned "Connection Refused" not "No route to host." I would also check to see if you are having a firewall related issue.
You need to open up the tcp port on your firewall
Using Linux, Find the iptables config file:
eric#dev ~$ find / -name "iptables" 2>/dev/null
/etc/sysconfig/iptables
Edit the file:
sudo vi /etc/sysconfig/iptables
Fix the file by adding a port:
# Generated by iptables-save v1.4.7 on Thu Jan 16 16:43:13 2014
*filter
-A INPUT -p tcp -m tcp --dport 15672 -j ACCEPT
COMMIT
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