Getting DNS error for curl localhost:8080 [closed] - http

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I'm trying to create a http server in go, when I run the code, I'm getting the output as
Listening on localhost:8080
But when I use curl localhost:8080 to test it I'm getting DNS error
The below code starts an HTTP server, listens on port 8080 incoming requests.
package main
import (
"fmt"
"html"
"log"
"net/http"
)
func main() {
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "Hello, %q", html.EscapeString(r.URL.Path))
})
log.Println("Listening on localhost:8080")
log.Fatal(http.ListenAndServe(":8080", nil))
}
This is the output I get when I run curl localhost:8080
$ curl localhost:8080
<HTML><HEAD>
<TITLE>Network Error</TITLE>
</HEAD>
<BODY>
<FONT face="Helvetica">
<big><strong></strong></big><BR>
</FONT>
<blockquote>
<TABLE border=0 cellPadding=1 width="80%">
<TR><TD>
<FONT face="Helvetica">
<big>Network Error (dns_unresolved_hostname)</big>
<BR>
<BR>
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
Your requested host "localhost" could not be resolved by DNS.
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica" SIZE=2>
<BR>
For assistance, contact your network support team.
</FONT>
</TD></TR>
</TABLE>
</blockquote>
</FONT>
</BODY></HTML>
Looks like its an DNS issue, I'm trying to setup the http server in a VM, how can I fix this error?


One guess is your http request is going through a proxy. You can unset the HTTP_PROXY variable and try again.
Otherwise, try using 127.0.0.1 or the IP address for your machine. :8080 means the HTTP server is binding to all IPs.

Related

How do I connect to the Docker Influxdb using the R client?

I am trying to make a connection to the Influx database using the R Influx DB client library to make a connection to a Influx database launched locally through Docker, here is the YAML file:
version: "3.7"
services:
influxdb:
image: influx
ports:
- "8086:8086"
- "8083:8083"
environment:
- INFLUX_DBNAME=exampledb
volumes:
- /Users/<user>/Desktop/influxdb/pv:/var/lib/influxdb
- /Users/<user>/Desktop/influxdb/influxdb.conf:/etc/influxdb/influxdb.conf:ro
deploy:
replicas: 1
restart_policy:
condition: on-failure
test:
build: ./test
image: test:latest
environment:
- INFLUX_ADDR=influxdb
- INFLUX_PORT=8086
- INFLUX_DBNAME=exampledb
- INFLUX_TBLNAME=exampletbl
depends_on:
- influxdb
deploy:
replicas: 1
restart_policy:
condition: on-failure
I obtained a influxdb.conf file:
local_machine$ docker run --rm influxdb influxd config > influxdb.conf
I modified the influxdb.conf file by setting auth-enabled to true and added a group named admin:
[http]
enabled = true
bind-address = ":8086"
auth-enabled = true
When I try to make a connection in R cli (or an R program in the test container) as follows:
>library(influxdbr)
>influx_conn <- influx_connection(host='influxdb', port=8086, user='admin', pass='admin')
I get the following error:
<HTML><HEAD>
<TITLE>Access Denied</TITLE>
</HEAD>
<BODY>
<FONT face="Helvetica">
<big><strong></strong></big><BR>
</FONT>
<blockquote>
<TABLE border=0 cellPadding=1 width="80%">
<TR><TD>
<FONT face="Helvetica">
<big>Access Denied (authentication_failed)</big>
<BR>
<BR>
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
Your credentials could not be authenticated: "Credentials are missing.". You will not be permitted access until your credentials can be verified.
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica">
This is typically caused by an incorrect username and/or password, but could also be caused by network problems.
</FONT>
</TD></TR>
<TR><TD>
<FONT face="Helvetica" SIZE=2>
<BR>
</FONT>
</TD></TR>
</TABLE>
</blockquote>
</FONT>
</BODY></HTML>
I tried exec'ing into the container and creating users and passwords and connecting with those, but I am still unable to connect. I am having a similar problem connecting using the Python client. I can curl into the Influxdb container, but I am unable to use the client library for either R or Python.
Based on comments, I also added a "group" in the config file at the bottom as specified in this R client connection example:
influxdb.config:
[admin]
scheme="http"
host="influxdb"
port=8086
user="admin"
pass="admin"
path="/"
# create connection object
# (here: based on a config file with group "admin" in it (s. package documentation))
con <- influx_connection(group = "admin")
Same error. So my question is, is there something else I need to set?

CFHTTP does not connect over SSL connection?

I have just installed an intermediate & primary SSL certificate on my VPS. Everything is working well, except when I make a cfhttp call:
<cfhttp url="https://advert.establishmindfulness.com/ad-zone-1/?categoryid=1" method="get" result="adzone" />
<cfdump var="#adzone#" />
From https://app.establishmindfulness.com to https://advert.establishmindfulness.com. These 2 subdomains are on the same server, and I am using a wildcard SSL certificate:
*.establishmindfulness.com
That covers all sub domains.
VPS environment
OS: Windows 2008R2 with IIS7
Application server: Lucee 4.5.2.018 final
Servlet Container: Apache Tomcat/8.0.28
Java: 1.8.0_66 (Oracle Corporation) 64bit
Do I need to install the intermediate.crt & primaryssl.crt into my keystore cacerts? Is this the problem?
I tried just installing the certificate.cer that I grabbed from Internet Explorer, but maybe this is the wrong approach?
I still get the error:
Error Detail
Unknown host: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

OK. For anyone who comes across this issue, instead of having to spend several hours pulling your hair out, I managed to get the connection to work:
This is taken from the following link:
https://groups.google.com/forum/#!topic/lucee/BPm8vYdgkPQ
Thank you Dominic Watson
I've just tried this and got it working:
Log in to Lucee server admin and navigate to "SSL Certificates"
Enter your host name "establishmindfulness.com" in the Host field (without the quotes)
Hit "list" button
Hit "install" button
That's it. The cfhttp call started working.

How to use nxLog

How to use nxLog? I installed it on my windows 7 and unix box, but not able to use it.
My Conf File(not sure its correct or not):
define ROOT C:\Program Files\nxlog
Moduledir %ROOT%\modules
CacheDir %ROOT%\data
Pidfile %ROOT%\data\nxlog.pid
SpoolDir %ROOT%\data
LogFile %ROOT%\data\nxlog.log
<Extension syslog>
Module xm_syslog
</Extension>
<Input in>
Module im_file
File 'D:\dotnet\Analytics\nxLog\association.log'
SavePos TRUE
ReadFromLast TRUE
PollInterval 1
Exec $Message = $raw_event; $SyslogFacilityValue = 22;
</Input>
<Output out1>
Module om_udp
Host 10.1.1.1
Port 514
Exec to_syslog_bsd();
</Output>
<Output out2>
Module om_udp
Host 10.1.1.2
Port 514
Exec to_syslog_bsd();
</Output>
<Route 1>
Path in => out1, out2
</Route>
And not sure what to write in host and port.

nxlog.log should contain the error messages to help you diagnose the problems.
"And not sure what to write in host and port."
The destination where the udp syslog should be sent to.

So your host is the destination IP address or hostname (haven't verified hostname functionality) of your destination. AKA where you want to send your logs to. The port is the port. After you update make sure to go to nxlog/data/nxlog.log to check and see if everything started up OK. If it did you should see no error messages at the bottom. I've only done it with TCP and it says that it's trying to establish a connection and then nothing below it. Not sure what you would see with UDP. I also see a message that says "Info nxlog started"
Good luck

tomcat http request aborted but https fine

I have a web application deployed on tomcat 7.0.23, and there are two connectors are set, almost default value.
<Service name="Catalina">
<Connector port="8080" protocol="HTTP/1.1"
connectionTimeout="20000"
compression="on"
compressableMimeType="text/xml"
address="SERVER_HOSTNAME" />
<Connector port="8443" protocol="HTTP/1.1" SSLEnabled="true"
maxThreads="400" scheme="https" secure="true"
address="SERVER_HOSTNAME"
clientAuth="false" SSLProtocol="ALL"
SSLCertificateFile="/PATH/tomcat-server.crt"
SSLCertificateKeyFile="/PATH/tomcat-server.rsa"
SSLCipherSuite="ALL:!ADH:!SSLv2:!EXPORT40:!EXP:!LOW"
compression="on" compressableMimeType="text/xml"/>
After tomcat just restarts, both http:8080 and https:8443 work fine. While after a few days, the 8080 will not work, but the 8443 still works fine. The meaning of "8080 not work" is when using firefox to access the http:8080, some resources like js/css files will unavailable randomly.
In firebug, sometimes the A.js file will be shown as "Aborted", sometime the B.js will be shown as "Aborted". I tried to access one single file, like http://:8080/js/A.js file, the result is also random, sometime the full content can be shown in browser, sometime http request is aborted.
I also tried to increase the connectionTimeout to "60000", the only change thing is in Firebug, the aborted request was 0B but now is actual size. The only way to make 8080 work fine is to restart the tomcat.
Please someone tell me what's the cause or which way I should try? Thanks.

Another process might be taking the port 8080 somehow. And this process does not respond correctly to requests you address to Tomcat.
So, next time you see this issue, before restarting Tomcat, check which process the port 8080 currently belongs to.
On Linux I use the following command for this:
netstat -nlpt | grep 8080
One of the columns (the last one if I remember correctly) will be the ID of the process that consumes the port.
In case you have a Windows setup, use
netstat -ano | find "LISTENING" | find "8080"
Then find this PID in the Task Manager.
FYI: Windows Task Manager – showing the PID

how a website is loaded in our browser

When I type www.google.com at my browser address bar, what exactly happens technically and how entire stuff is loaded. Considering the same HTTP page is being loaded...
what is role of DNS server, IP address, MAC address, subnet mask, proxy setting, default gateway in this case.
Does it make any different if I am in different class of network?

You are asking about all things at once, it's a big concept.
Still in short.
When you type www.google.com (or any other site name) then the request goes to the DNS server which translates the URL into an IP address.
Read here more: http://en.wikipedia.org/wiki/Domain_Name_System
Then the request goes to server where the website is being hosted, the server which is providing hosting service for the website contains the website-stuff that has to be shown to the world.
Read about apache server: http://en.wikipedia.org/wiki/Apache_HTTP_Server
Subnet: http://en.wikipedia.org/wiki/Subnetwork
does it make any different if i am in different class of network?
No, it doesn't make any difference if you are in different class of network.
(Study about routers: http://en.wikipedia.org/wiki/Routers)

Points to help you out:
Every computer that belongs to a network -including yours has an ip address.
Every network has hosts under it. The network may be divided into subnets
The ip addressing is hierarchial.This helps in routing
IP addresses may be assigned manually or by the DHCP server
Manual-IP configuration
DHCP-Dynamic Host Configuration Protocol
All packets that are sent to your ip address come through your isp network - this includes switches and routers
Packets from other networks are forwarded by this ip address. Once they reach the nearest switch. Switches use your MAC address to send packets to your computer. The MAC address is obtained by ARP
The gateway address is the path through which packets are sent out of your network or your ISP's
Proxy servers are servers that allow connections through them
To understand more about how this works, download Wireshark:
Start the sniffer and then load google.com in your browser.
You will notice the following
The browser first sends a DNS request with the hostname to the DNS server of your ISP (or your network if any)- DNS finds out the ip address from the hostname.
The DNS server replies with the IP address of the server
The browser then sends the HTTP request
This is in the form e.g
GET /index.html HTTP/1.1
The server responds with the format
The data is sent to the user
Usually if a webpage is requested, it is in HTML format(with javascript,css,etc). This is then parsed and processed by the browser to get the webpage we see.
To test this :
ON LINUX,
type
telnet stackoverflow.com 80
in the terminal.
As soon as it gets connected,type the following (quickly before it gets disconnected):
GET /index.html HTTP/1.1 (enter)
Host: stackoverflow.com (enter)(enter)
to see the response
ON WINDOWS
Download the putty client and fill the host as stackoverflow.com, port as 80, and choose Connection type as Telnet.
As soon as it gets connected, repeat same steps as above to see the response.

The examples shown above illustrate how things work from Layer 7, but not Layer 3+ from your device's perspective. I would look at using tcpdump/wireshark to try and dump all of the network packets if you're interested in getting those kinds of low-level details. An example's provided below (run on FreeBSD).
Notes:
- Be sure to start wireshark/tcpdump before your web browser/client first so the packets get captured.
- Specify the right port when starting wireshark/tcpdump; filtering the connection via a DNS address might not work in all cases if the remote webserver has load balancing/failover setup.
Window with tcpdump:
# tcpdump -A tcp port 80
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on em0, link-type EN10MB (Ethernet), capture size 65535 bytes
capability mode sandbox enabled
01:48:17.917640 IP 10.0.2.15.50636 > nuq05s01-in-f20.1e100.net.http: Flags [P.], seq 1631738201:1631738227, ack 30720002, win 65535, length 26
E..BP.#.#...
...J}.t...PaBYY....P...F5..GET /index.html HTTP/1.1
01:48:17.918119 IP nuq05s01-in-f20.1e100.net.http > 10.0.2.15.50636: Flags [.], ack 26, win 65535, length 0
E..(.U..#..{J}.t
....P......aBYsP...'+........
01:48:18.072501 IP 10.0.2.15.50636 > nuq05s01-in-f20.1e100.net.http: Flags [P.], seq 26:28, ack 1, win 65535, length 2
E..*P.#.#...
...J}.t...PaBYs....P...F...
01:48:18.072662 IP nuq05s01-in-f20.1e100.net.http > 10.0.2.15.50636: Flags [.], ack 28, win 65535, length 0
E..(.X..#..xJ}.t
....P......aBYuP...')........
01:48:18.074353 IP nuq05s01-in-f20.1e100.net.http > 10.0.2.15.50636: Flags [P.], seq 1:687, ack 28, win 65535, length 686
E....Y..#...J}.t
....P......aBYuP...Z...HTTP/1.0 400 Bad request: request header 'Host' missing
Content-type: text/html; charset="iso-8859-1"
<html>
<body>
<h3> Request denied by WatchGuard HTTP proxy. </h3>
<b> Reason: </b> request header 'Host' missing <br>
<hr size="1" noshade>
<b> Method: </b> GET <br>
<b> Host: </b> 74.125.239.116 <br>
<b> Path: </b> /index.html <br>
<hr size="1" noshade>
</body>
<!-- PAD --></html>
01:48:18.074512 IP nuq05s01-in-f20.1e100.net.http > 10.0.2.15.50636: Flags [F.], seq 687, ack 28, win 65535, length 0
E..(.Z..#..vJ}.t
....P......aBYuP...$z........
01:48:18.074683 IP 10.0.2.15.50636 > nuq05s01-in-f20.1e100.net.http: Flags [.], ack 688, win 65014, length 0
E..(P.#.#...
...J}.t...PaBYu....P...F...
01:48:18.077023 IP 10.0.2.15.50636 > nuq05s01-in-f20.1e100.net.http: Flags [F.], seq 28, ack 688, win 65535, length 0
E..(P.#.#...
...J}.t...PaBYu....P...F...
01:48:18.077070 IP nuq05s01-in-f20.1e100.net.http > 10.0.2.15.50636: Flags [.], ack 29, win 65535, length 0
E..(.[..#..uJ}.t
....P......aBYvP...$y........
Window with telnet:
# telnet www.google.com 80
Trying 74.125.239.116...
Connected to www.google.com.
Escape character is '^]'.
GET /index.html HTTP/1.1
HTTP/1.0 400 Bad request: request header 'Host' missing
Content-type: text/html; charset="iso-8859-1"
<html>
<body>
<h3> Request denied by WatchGuard HTTP proxy. </h3>
<b> Reason: </b> request header 'Host' missing <br>
<hr size="1" noshade>
<b> Method: </b> GET <br>
<b> Host: </b> 74.125.239.116 <br>
<b> Path: </b> /index.html <br>
<hr size="1" noshade>
</body>
<!-- PAD --></html>
Connection closed by foreign host.

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