I recently started using flutter to create an app that has video and audio calling, so I thought of using WebRTC to accomplish this. However, when I tried to create a local WebRTC server from the WebRTC Github it doesn't let me connect to it. When I run the server from the command prompt it tells me that the server is listening at the given local IP, but when I try to connect to it, it says the site can't be reached. Also when I ping the url it says the ping request could not find the host. Any kind of help would really be appreciated.
WebRTC server: https://github.com/flutter-webrtc/flutter-webrtc-server
Starting server in command prompt
netstat when server running
pinging server
The IP 0.0.0.0 is not the IP address the server is binding/listening too.
It is a common way that servers allow configurion 0.0.0.0 to express binding to all IPv4 the host has (see https://en.wikipedia.org/wiki/0.0.0.0 ). To acually reach your server use whatever IP you have on the host (if you are starting the server on your workstation 127.0.0.1 ought to work)
Ping on Windows is only ICMP if I am not mistaken, this means a TCP port number is not part of it's expected input. Eg. "0.0.0.0:8086" is not a valid target for that command (see https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/ping )
>ping 0.0.0.0:8086
Ping request could not find host 0.0.0.0:8086. Please check the name and try again.
>ping 0.0.0.0
Pinging 0.0.0.0 with 32 bytes of data:
PING: transmit failed. General failure.
PING: transmit failed. General failure.
Ping statistics for 0.0.0.0:
Packets: Sent = 2, Received = 0, Lost = 2 (100% loss),
Control-C
^C
>ping 127.0.0.1
Pinging 127.0.0.1 with 32 bytes of data:
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Reply from 127.0.0.1: bytes=32 time<1ms TTL=128
Ping statistics for 127.0.0.1:
Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
Control-C
^C
Since what you are trying to connect to is a webserver you could use something like curl instead to try to verify your connection. Should be available without any further install if you are on Windows 10 1803 or newer.
>curl https://0.0.0.0:8086
curl: (7) Failed to connect to 0.0.0.0 port 8086: Address not available
>curl https://127.0.0.1:8086
<html><head><title>Unauthorized</title></head><body><h1>401 Unauthorized</h1></body></html>
Some browsers might support https://0.0.0.0:8086 in a similar way server do but I wouldn't rely on it. Go with https://127.0.0.1:8086 or a non localhost IP address of the host.
Related
I installed three operating systems(let's say 3 hosts) in VMware, all with NAT mode. 3 hosts are named centos, centos 1,centos 2.(As the pic shows below)
3 hosts in VMware
The first host's IP address is 192.168.248.132, the second is 192.168.248.136, and we don't need to know third host's IP because it's not related to this issue.
I typed the command "ping 192.168.248.136", and the output on the screen is:
PING 192.168.248.136 (192.168.248.136) 56(84) bytes of data.
64 bytes from 192.168.248.136: icmp_seq=1 ttl=64 time=0.435 ms
64 bytes from 192.168.248.136: icmp_seq=2 ttl=64 time=0.313 ms
64 bytes from 192.168.248.136: icmp_seq=3 ttl=64 time=0.385 ms
This means ping command has succeeded and host no.2(whose IP addr is 192.168.248.136) has received ICMP and replied.
Meanwhile, I typed the command "tcpdump -i ens33" in host no.3. If everything had worked correctly, host no.3 would not have received any data between host no.1 and host no.2, because ICMP is neither broadcast nor multicast, so only host no.1 and 2 can send and receive. Also, host no.3's network interface is not promiscuous mode, so it can only receive it's own frame. The output from host no.3 below can show it is not promiscuous mode.
[root#localhost usr]# ifconfig
ens33: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 192.168.248.137 netmask 255.255.255.0 broadcast 192.168.248.255
inet6 fe80::b488:bc2c:3770:a95f prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:0d:dc:86 txqueuelen 1000 (Ethernet)
RX packets 351081 bytes 512917768 (489.1 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 34947 bytes 2166260 (2.0 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
flag is 4163<UP,BROADCAST,RUNNING,MULTICAST>, "PROMISC" is not mentioned, so it is not promiscuous mode.
However, after I typed "tcpdump -i ens33" in host no.3, something appeared on the screen:
06:28:11.511233 IP 192.168.248.132 > 192.168.248.136: ICMP echo request, id 3137, seq 5, length 64
06:28:11.511503 IP 192.168.248.136 > 192.168.248.132: ICMP echo reply, id 3137, seq 5, length 64
Host no.3 received the dataflow between no.1 and 2, and this was supposed to be sent to no.2, but no.3 received it.
So here comes the question, why can host no.3 receive packet which was not supposed to be sent to it?
tcpdump by default activates "promiscuous mode" making it able to see anything on the network it is connected to (even if not explicitly sent to it).
the three hosts seem to be connected to a virtual switch that do not isolate the hosts from each other.
Mongodb 4.4.14 is intalled in Mac OS Monterey version 12.4.
Connection from Robo 3T installed in Mac itself works.
Connection from mongo cli in mac itself also works:
$ mongo
MongoDB shell version v4.4.14
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("ab8018b3-c4f2-4236-8c3b-abef5468bb03") }
MongoDB server version: 4.4.14
---
The server generated these startup warnings when booting:
2022-06-02T15:59:13.574+05:30: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
---
MongoDB Enterprise >
While connecting from Studio 3T installed in Windows Virtual Machine (it is Parallels software, NOT VirtualBox) to this mongodb 4.4, receiving the following error:
Connection failed.
SERVER [192.168.1.2:27017] (Type: UNKNOWN) CONNECTING
Details:
Timed out after 5000 ms while waiting to connect. Client view of cluster state is {type=UNKNOWN, servers=[{address=192.168.1.2:27017, type=UNKNOWN, state=CONNECTING}]
Note that the Mac host IP address is 192.168.1.2. And ping from Windows VM to Mac works fine. Also disabled the firewall in Windows.
C:\Windows\system32>ping 192.168.1.2
Pinging 192.168.1.2 with 32 bytes of data:
Reply from 192.168.1.2: bytes=32 time<1ms TTL=64
Reply from 192.168.1.2: bytes=32 time<1ms TTL=64
Reply from 192.168.1.2: bytes=32 time<1ms TTL=64
Reply from 192.168.1.2: bytes=32 time<1ms TTL=64
Ping statistics for 192.168.1.2:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 0ms, Maximum = 0ms, Average = 0ms
C:\Windows\system32>
How to resolve this error?
In the parallels software network configuration, selected "Shared Network (Recommended)" and it worked fine.
I can ssh into the server say abc.xyz on port 22 but i can't remote debug it in Eclipse. Here is the additional info :
Server startup arguments -
-Xdebug -Xrunjdwp:transport=dt_socket,address=1234,server=y,suspend=n
Confirmation from logs -
Listening for transport dt_socket at address: 1234
When I telnet on my local system -
local-machine% telnet abc-xyz 1234
Trying xx.xx.xx.xx...
telnet: connect to address xx.xx.xx.xx: Connection timed out
telnet: Unable to connect to remote host: Connection timed out
When I telnet on the server(abc.xyz) -
abc-xyz% telnet localhost 1234
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
Connection closed by foreign host.
I've tried setting up tunnel via -
ssh -L 1234:localhost:1234 user#abc-xyz
ssh -L 1234:127.0.0.1:1234 user#abc-xyz
I'm attaching debugger in Eclipse with this config -
Connection type - Standard (Socket attach)
Host - localhost
Port - 1234
Can't get Eclipse to attach to 1234.
After setting up SSH Tunnel, if i manually try to connect to the port, i get this response -
local-machine% telnet localhost 1234
Trying 127.0.0.1...
Connected to localhost.localdomain (127.0.0.1).
Escape character is '^]'.
Connection closed by foreign host.
and I see an entry in catalina.out as:
channel 4: open failed: connect failed: Connection refused
Any help would be appreciated.
EDIT - 1:
I ran
abc-xyz% ~#
and got the following output:
The following connections are open:
#2 client-session (t4 r0 i0/0 o0/0 fd 7/8 cc -1)
#3 direct-tcpip: listening port 1234 for localhost port 1234, connect from 127.0.0.1 port 23456 (t4 r1 i0/0 o0/0 fd 10/10 cc -1)
I think ssh tunneling is working, it's just the way i'm connecting with Eclipse which is going wrong here.
I just had to increase timeout. (Can be done via Window->Preferences->Java->Debugging. Set it to some appropriate value.)
I'd like to start a Tomcat debug session on my remote host from Eclipse, but it fails with this error:
Failed to connect to remote VM
com.sun.jdi.connect.spi.ClosedConnectionException
My Tomcat is, I think, correctly configured to received debug session on port 8000:
tomcat 18771 1 1 17:18 ? 00:00:16 /usr/lib/jvm/java/bin/java -Xdebug -Xrunjdwp:transport=dt_socket,address=8000,server=y,suspend=n -Djava.rmi.server.hostname=10.30.0.17 -Dcatalina.ext.dirs=/usr/share/tomcat5/shared/lib:/usr/share/tomcat5/common/lib -Djavax.sql.DataSource.Factory=org.apache.commons.dbcp.BasicDataSourceFactory -Djava.endorsed.dirs=/usr/share/tomcat5/common/endorsed -classpath /usr/lib/jvm/java/lib/tools.jar:/usr/share/tomcat5/bin/bootstrap.jar:/usr/share/tomcat5/bin/commons-logging-api.jar:/usr/share/java/mx4j/mx4j-impl.jar:/usr/share/java/mx4j/mx4j-jmx.jar -Dcatalina.base=/usr/share/tomcat5 -Dcatalina.home=/usr/share/tomcat5 -Djava.io.tmpdir=/usr/share/tomcat5/temp org.apache.catalina.startup.Bootstrap start
There is a firewall between my PC and the remote server, but the port is well opened, as I can see these packets with tcpdump on the server:
17:41:17.110977 IP X.X.X.X.57010 > Y.Y.Y.Y.irdmi: S 868833744:868833744(0) win 8192 <mss 1460,nop,wscale 8,nop,nop,sackOK>
17:41:17.111183 IP Y.Y.Y.Y.irdmi > X.X.X.X.57010: S 3571247457:3571247457(0) ack 868833745 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 7>
17:41:17.112624 IP X.X.X.X.57010 > Y.Y.Y.Y.irdmi: . ack 1 win 256
17:41:19.113216 IP Y.Y.Y.Y.irdmi > X.X.X.X.57010: F 1:1(0) ack 1 win 46
17:41:19.114246 IP X.X.X.X.57010 > Y.Y.Y.Y.irdmi: P 1:15(14) ack 1 win 256
17:41:19.114279 IP Y.Y.Y.Y.irdmi > X.X.X.X.57010: R 3571247458:3571247458(0) win 0
The only message writtent in Tomcat logs is
Debugger failed to attach: timeout during handshake
I can't figure out what's wrong dispite informations I found on the web.
Can anyone can help me?
My server: RHEL 5.9, Tomcat 5.5, java 1.6
Regards,
Robert
I solved my issue : there were a packet inspection activated on the firewall between my PC and the server. It lets certain TCP packets trough, so the TCP handshack can occure, but block data TCP packet.
As I understand, first, a TCP connection is made, then an application handshake is done by the java server with TCP data packet. As data packet was filtered by the firewall, the application handshake could not been completed, and the application close the TCP connection by sending a FIN packet.
Regards,
Robert
#!/usr/bin/perl
use Net::Ping;
$p = Net::Ping->new();
my $main_ip="$ARGV[0]";
if ($p->ping($main_ip,1)){
$result=true;
print "$main_ip is alive \n";
}else{
print "$main_ip is down \n";
}
I am using above perl script to ping check the server. It worked fine all the cases except for IP 192.168.0.168.
$ perl test.pl 192.168.0.168
192.168.0.168 is down
]$ ping 192.168.0.168
PING 192.168.0.168 (192.168.0.168) 56(84) bytes of data.
64 bytes from 192.168.0.168: icmp_seq=1 ttl=64 time=0.304 ms
64 bytes from 192.168.0.168: icmp_seq=2 ttl=64 time=0.355 ms
64 bytes from 192.168.0.168: icmp_seq=3 ttl=64 time=2.94 ms
64 bytes from 192.168.0.168: icmp_seq=4 ttl=64 time=0.388 ms
--- 192.168.0.168 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3292ms
rtt min/avg/max/mdev = 0.304/0.997/2.944/1.124 ms
]$ ping 192.168.0.18
PING 192.168.0.18 (192.168.0.18) 56(84) bytes of data.
From 192.168.0.181 icmp_seq=2 Destination Host Unreachable
From 192.168.0.181 icmp_seq=3 Destination Host Unreachable
From 192.168.0.181 icmp_seq=4 Destination Host Unreachable
--- 192.168.0.18 ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3292ms
pipe 3
]$ perl test.pl 192.168.0.18
192.168.0.18 is down
I had no clue even I have increase ping timeout but the results same
The only problem i can think of is, that the ping command uses the ICMP protocol as default, while Net::Ping uses TCP. You can switch Net::Ping to ICMP by creating your object like this:
my $p = Net::Ping->new( 'icmp' );
Take note, that making ICMP pings requires root privilege on Unix.
In order to send icmp packets you must have rights to create raw sockets, i.e. have root rights.
I suppose you running ping.pl as ordinary user, but you need to be root
ls -al `which ping`
-rws--x--x 1 root root 39640 Dec 17 2011 /bin/ping
^
|
suid bit
ping program has a suid bit, which allows to run ping program with root rights.
By default Net::Ping tries to connect to echo port (7/tcp), if it gets ECONNREFUSED - this means that host is up but refuses connection (nothing is listening on that port). if connect breaks on timeout, this means that host is down.
But! I can block all connection to 7/tcp by firewall:
iptables -I INPUT -p tcp --dport 7 -j DROP
and... voila, i get down instead of alive
So, you should check firewall on your failure pinged host