If I enter "port 2000" in the capture filter I am not getting packets from my application that is communicating via TCP on port 2000... Any idea why?
If the server is on the same host, your application may be using the loopback interface.
On Linux you can listen to the loopback interface by selecting the "lo" device.
On Windows it's a bit trickier.
Wireshark will not capture local traffic on windows machine without some jiggering. see Devon_C_Millers answer
Related
I am using a mac and trying to capture packets live packets when I am loading up a website. I am connected over Wifi and am able to capture packets without those filters being used.
However when I enter in 'tcp port http' I am coming up empty handed.
Any suggestions to solve this?
When you use a port name in a capture filter expression, libpcap (the packet capture library that Wireshark uses) needs to convert the name into a number that it can use to match against bytes the captured packet. It does so by looking up the port name in /etc/services. (Specifically, it calls getaddrinfo, which usually looks up the port in /etc/services on macOS and Linux, and C:\system32\drivers\etc\services on Windows.) If I open /etc/services on my system here, "http" corresponds to port 80.
However, the modern web doesn't really use port 80 any more. Most web traffic these days is encrypted using HTTPS, and the IANA-assigned port for HTTPS is 443.
You might have better luck using "tcp port 443" or "tcp port 443 or tcp port 80" to make sure you capture both HTTP and HTTPS.
As far as I know, the filter has to be tcp.port == 80.
But if your Wireshark doesn't capture anything (without filter), you may check your installation and the wiki.
I need to open port#42474 on my Windows 10 system for penetration testing purposes.
I added it to the inbound list of my Windows Defender Firewall (both TCP and UDP protocol), and it is enabled.
However, whenever I am trying to ping this port on my machine using telnet it is throwing an error as
Connecting To localhost...Could not open connection to the host, on port 42474: Connect failed
I am able to use telnet to ping other sites such as google.com. But not this port on my machine. Below is the command I am running to test the port and the error:
Port
Telnet error
telnet localhost 42474
Do I need to do anything else to open port#42474?
How do I verify if this port is available for use?
TCP ports are bi-directional, so check these tips:
Verify your service on this port is running: netstat -a
Be sure your firewall isn't blocking (try to deactivate it: if it works well, your rule isn't correct)
Search for your service log: maybe,
it receive information, but it's not able to reply. I recommend you to use PuTTY or Kitty (which is my favorite, because it's portable without registry keys modification), and try to connect on this port.
If you need a tool that able to listen on the port, see this post: Utility to open TCP port to listen state and netcat.
You can use the Python programming language. More specifically, the socket library:
import socket
hote = "localhost"
port = 4444
socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
socket.connect((hote, port))
print "Connection on {}".format(port)
socket.send(u"Hey my name is Abdx!")
print "Close"
socket.close()
I am trying to capture traffic to 127.0.0.1 on a Windows 10 computer with Wireshark. I have installed NPCap but it does not appear to be capturing that tr5affic.
Looking at the interface options in Wireshark for the loopback adapter I see it has IPV4 address of 0.0.0.0. Is this correct and if so, how do I capture the localhost traffic.
Thanks,
Sid
It seems the way to capture localhost traffic for use with Wireshark is to use "RawCap" and then examine the captured data in WireShark.
RawCap.exe may be downloaded from here -> http://www.netresec.com/?page=RawCap
Sid
Wireshark used to be installed with Winpcap behind the scenes, but Winpcap, to my knowledge, never supported packet capture over localhost. And of course, Winpcap has not been updated since 2013 IIRC.
Npcap, which is the supported replacement for Winpcap, does support localhost packet capture. And since Wireshark now delivers Npcap instead of Winpcap, it is capable of capturing and displaying packets captured on localhost.
To use the functionality, open Wireshark. At the bottom of the opening screen, there should be an "Adapter for loopback traffic capture." Double-click that, and you're off!
Two quick points.
I'm using Wireshark v3.2.7.
Packets captured off the loopback adapter do not start with an Ethernet frame, for example. They start with what Wireshark calls a Null/Loopback header. It is a 4-byte header that typically has a value of 2 in big-endian order. Read more here.
HTH
This is more of a theory question for more understanding.
In order to do port forwarding we update sshd_config and provide the information of local port(a) and remote port(b) among which we need to perform forwarding. After this forwarding config is done, ssh tunnel will be used to forward packets between a <-> b.
But internally, how does this work? when I do https://localhost:a, how does packet move from port a to ssh tunnel port 22 and on the other side from port 22 to port b?
If you are interested about the internals, openssh is the most popular implementation of SSH protocol and it is open source with code available on GitHub.
To answer a bit your question, it works as every other network communication. If you are not familiar with it, check how network socket works. Port forwarding is doing just proxy between the ends and sends the data inside the encrypted channel, instead of outside as the direct socket would.
Anyway, it is easier to google a bit. Ubuntu has a nice explanation in their documentation:
To get the most out of port forwarding, it's helpful to know a bit about how the Internet works.
The Internet assigns computers virtual "ports", a bit like the USB ports on the back of your computer:
To let a digital camera share pictures with your PC, you connect the USB port on the camera to any USB port on the PC. The computer then talks to the camera about your photos, and shows you the result.
To let a web server share pages with your PC, you connect the web server port on the server to any Internet port on the PC. The computer then talks to the server about your page, and shows you the result.
Unlike a USB port, there is no physical component to an Internet port. There's no actual wire, or actual hole on the back of your computer. It's all just messages being sent over the Internet. Like other "virtual" computer concepts, Internet ports are just an analogy that help to explain what your computer is doing. Sometimes, that analogy breaks down:
There are two types of Internet port: normal "TCP" ports and strange "UDP" ports (which won't be covered here).
Unlike USB ports, every computer has exactly 65,535 numbered TCP ports, some of which have a special purpose. For example, port number 80 is your web server port, so your web browser knows it should connect to port number 80 in order to download a web page.
Connections between Internet ports can be patched together, so a connection from computer A to computer B on port 12,345 could be patched through to port number 80 on computer C. This is known as port forwarding.
I wrote a java program of TCP/IP Client which is supposed to read data from TCPIP server device.
Problem is when I give the IP and Port of the Device, java gives error of "Connection Time out". Obviously this is problem of not connecting to that Device.
I want to know if there is way to know where the problem is? Whether that TCPIP server device is not reachable (if no, then how to check it )
whether Its the router / network issue that TCPIP Client and Server has to be on same network or use same router to communicate. OR Just IP:Port is enough.
How on my computer may I know that TCPIP server device is turned on and streaming??
P.S. That TCPIP Server device can also be connected with blutooth connection. can i read streaming through blutooth in Java?? if yes what/How should I do it?
I want to know if there is way to know where the problem is? Whether
that TCPIP server device is not reachable (if no, then how to check it
)
Use telnet from the client - it will try to connect to the remote server at the port that you specify. For example telnet google.com 80 attempts to reach google.com on port 80. You could also use an IP address in place of "google.com". If you are on a windows box, you might have to enable telnet first.
You can also use netstat on the server. It should say the ports that are currently open and the state that they are in. For example, your Java server program should be listening on the port, so the state should say LISTEN.