I am developping a FTPS client in a Embedded system with LWIP and mbedTLS stacks.
For now, what I do is :
Get an IP adress with DHCP
Get IP address of the server with DNS
Start a TCP connection to the server ( the control connection)
Telling the FTP server that I want to work with the TLS protocol with the command AUTH TLS
Handshake of the TLS protocol with the server
Validate the x509 certificate that the server sends
Telling the client that I want to work in passive mode and that i want to read a file with the command RETR.
Now, I need to open a data connection to read my file. So what I wanted to know is does the data connection is secured in the same way the control connection is ? That means do I have a certificate to validate ? Is the handshake the same ?
If this isn't clear let me know i'm not an expert at all in this area.
Thank you for your future responses
In explicit FTPS connection after you send AUTH command, the data connection is secured all the way. Depending on Active/Passive connection the data connection is opened through port 20(Active) or some random port negotiated(Passive).
You don't need any extra handshakes as far as I know.
You might or might not be able to configure if you want to reuse the same session ID created in opening the control channel. This is related for server to know that data connection has been established by the same client which opened the control channel. Some server require this, some servers allow this, some servers does not support this.
Related
Is is possible to configure HAProxy to only allow single connection per client certificate (based on CN or other attribute)?
Each client should be able to connect even if it has already open connections, though, after successful authentication any previous connection for that certificate should be dropped immediately.
I do not think ACL's would work for this purpose.
Thanks in advance
I'm working on designing a server, in which the protocol allows for the client to open additional physical connections to the server which operate in the context of a single logical connection.
One thought I had was that, if we're using ssl, we'll need to do another ssl handshake for the new connection. It seems to me that it should be possible to send some secret to the client over the original, secure connection that would allow the new connection to be securely established without a handshake (similarly to what I've read about ssl session reuse).
Is this actually possible?
SSL already does this. Provided both ends support it, there is a feature called 'session resumption' which allows a new connection via an existing SSL session, via a much abbreviated handshake, without the certificate exchange and negotiation of shared secrets.
Yes, by reusing SSL Session. You can do this by using PEM_write_bio_SSL_SESSION and PEM_read_bio_SSL_SESSION and then adding it to SSL Context.
Keep in mind you only need to do this in client mode, server mode does this automatically for you.
I'm developing a client/server Winforms application. Clients connect to server using internet and use WCF's netTCPBinding to talk to server.
Communicating in a secure channel is very important for me and since NetTCP binding is secured by default with TLS, it seems like I don't have to do anything. Do I?
How can I monitor the encrypted data sent/received between my client/server in localhost? I used RawCap to capture data and opened the dump file in Wireshark. But I don't know how I should check for TLS security in packets. dump file is full of unkown TCP packets (not from my software) with vcom=tunnel info for most of them.
TCP binding security element is set to Transport by default. This indicates requirement that transport session must be encypted. If you cannot establish TLS session service will reject the call.
You can use something like TCPMon which will show TLS traffic albeit encrypted. Also there is SSLDump
Is it not possible to specify the local client port used for server calls via NetTcpBinding?
NetPeerTcpBinding support this - I find it hard to believe there's no way to specify the local port (and IP Address for that matter) on clients.
I need to be able to use port sharing and I can't do this if I don't know what port the client is listening on. I won't be able to share the port (and IP) with another client so it can connect.
The only work-around I found is something like this:
Client A opens a connection to Server
Server logs the IP and Port of Client A
Server shares this info. with
Client B
Client B should be able to
connect to Client A on specified IP
and Port (in theory)
This is known as TCP/IP NAT hole punching I believe. Anyone with experience in this?
You probably don't understand the communication pattern with NetTcpBinding. It works this way:
The client opens connection to the server
Two-way communication: The client calls the server and gets the response over the same connection.
Duplex communication: The client calls the server. The server stores reference to the channel somewhere (you must implement this). Once the server wants to notify client about anything it takes stored channel and calls the client on the connection established by the client during its first call.
The server never opens connection to the client. The client doesn't expose any address with port for incomming communication. If you want to do that you must implement service on the client in the same way you did it on the server and you must manully send the address and port to the service exposed by the server.
The difference with NetPeerTcpBinding is that there is no real server and any client must be able to get incomming request. NetTcpBinding is for client-server scenarios where the server is the only peer able to process incomming requests. Because of that only the server needs to define an address and a port.
I am creating an authentication server for some projects I'm working on. This authentication server works by receiving and transmitting data to users trying to authenticate. The user can send data to the server succesfully but when sending back it requires port forwarding. I read a way that I would not require port forwarding by using reverse connection but I have no idea how to get it working. I found a tutorial and tried to implement but when it tries to connect to read the stream it says the connection is refused.
Any ideas?
If the user is already connecting to the server, why not just keep the (existing) connection open, and use that for bidirectional communication?
I can see no reason to open a second connection from the server back to the client.