I'm making network requests with my mobile app. I would like to simulate a server for error handling because the server I will eventually make requests to is not up yet
I don't want to spend a lot of time coding my own server
I want to make a request to a server, and have the server respond with..
a 400 response
a 200 response
no response
Terminal commands for each test
everywhere that says 11.11.11.11 you should enter your IP Address instead
400 response test
while true; do echo -e "HTTP/1.1 400 Bad Request\n\n $(date)" | nc -l 11.11.11.11 1500; sleep 3; done
when the test is complete, hit control + c in the terminal until the process stops
200 response test
while true; do echo -e "HTTP/1.1 200 OK\n\n $(date)" | nc -l 11.11.11.11 1500; sleep 3; done
when the test is complete, hit control + c in the terminal until the process stops
No response test
nc -l 11.11.11.11 1500
when the test is complete, hit control + c in the terminal until the process stops
Related
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
An activator template project was created by
activator new rest-benchmark simple-rest-scala
cd rest-benchmark
activator clean stage
target/universal/stage/bin/rest-benchmark -Dplay.crypto.secret=1234
the template can be found here
Then I run ApacheBench to get a rough idea of playframework's throughput:
ab -n 20000 -c 5 http://127.0.0.1:9000/books
which always give similar result - timeout at around 16.3k-th request:
apr_socket_recv: Operation timed out (60)
Total of 16345 requests completed
However, if I run ab with -k KeepAlive:
ab -k -n 20000 -c 5 http://127.0.0.1:9000/books
The benchmark was able to complete.
I have several questions:
Why always timeout when Keep Alive is absent? Shouldn't play be able to handle requests regardless of this header? Or is it my OS keep the connection open, hence no further requests can be processed?
Why around the 16300-th request? Is it related to ulimit?
If missing Keep Alive will cause connection timeout, what can I do in production?
Edit: Switched to play 2.5.4
Edit2: Changed app launch command as marcospereira suggested, observing same result
Recently I am working on LBaaS service. When I set up a pool and it serves,
the haproxy process randomly returns 503:
503 Service Unavailabe
No server is available to handle this request
And I am pretty sure when this problrm happened, member servers are up.
Anyone can help me abt this problem?
PS:when i first build members in the loadbalancer，the status is active, however,it will turn to inactive in a few minutes. And I find a way to resolve this via executing
echo -e 'HTTP/1.0 200 OK\r\n\r\n<serverX>' | nc -l -p
then the status of members turns to active.
Ahaaaa...
Finally i got it, I am really careless..
i should use while true when i execute
echo -e 'HTTP/1.0 200 OK\r\n\r\n' | nc -l -p
otherwise, this command will be only executed by once.
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.
My Perl script gets stuck with an exit status when trying to use the ping command.
According to this website:
If ping does not receive any reply packets at all it will exit with code 1. If a packet count and deadline are both specified, and fewer than count packets are received by the time the deadline has arrived, it will also exit with code 1. On other error it exits with code 2. Otherwise it exits with code 0. This makes it possible to use the exit code to see if a host is alive or not.
To list the results:
Success: code 0
No reply: code 1
Other errors: code 2
Note that the page I link to says "Linux/Unix ping command", but other systems, or perhaps even variants of Linux and Unix, might vary this value.
If possible, I would test on the system in question to make sure you have the right ones.
It's worth doing some testing on this on your OS. e.g on OSX
Resolvable host which is up
ping -c 1 google.com ; echo $?
Replies:
PING google.com (173.194.38.14): 56 data bytes
64 bytes from 173.194.38.14: icmp_seq=0 ttl=51 time=16.878 ms
--- google.com ping statistics ---
1 packets transmitted, 1 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 16.878/16.878/16.878/0.000 ms
Returns
0
Resolvable host which is down/does not respond to ping
ping -c 1 localhost ; echo $?
Replies:
PING stuart-woodward.local (127.0.0.1): 56 data bytes
--- stuart-woodward.local ping statistics ---
1 packets transmitted, 0 packets received, 100.0% packet loss
Returns:
2
Non Resolvable host
ping -c 1 sdhjfjsd ; echo $?
Replies:
ping: cannot resolve sdhjfjsd: Unknown host
Returns:
68
The ping utility returns an exit
status of zero if at least one
response was heard from the specified
host; a status of two if the
transmission was successful but no
responses were received; or another
value (from ) if an error
occurred.
http://www.manpagez.com/man/8/ping
The actual return values may depend on your system.
Successful connection will always return code 0, whilst failed connections will always return code 1 and above.
To test this out, try this snippet
#!/bin/bash
light_red='\e[1;91m%s\e[0m\n'
light_green='\e[1;92m%s\e[0m\n'
ping -c 4 -q google.comz
if [ "$?" -eq 0 ]; then
printf "$light_green" "[ CONNECTION AVAILABLE ]"
else
printf "$light_red" "[ HOST DISCONNECTED ]"
fi
You should also take into account that if the ping for example receives a 'network unreachable' icmp reply, it will be counted as reply an thus returns success status 0 (tested with cygwin ping on windows). So not really useful for testing if a host is alive and IMO a bug.
Try man ping from the command line. The return values are listed near the bottom.