# Usage of MbedTLS with TCP sockets
**URL:** https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811
**Category:** General Usage
**Created:** [May 9, 2021, 7:41am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811 "2021-05-09T07:41:01Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@ligert123](https://discourse.julialang.org/u/ligert123)
#### Post date: [May 9, 2021, 7:41am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811/1 "2021-05-09T07:41:01Z")
Hello, i have been trying to setup an encrypted TCP server connection using MbedTLS and i have been having trouble getting it working.
I keep receiving: `MbedTLS error code -31104: SSL - Processing of the ServerHello handshake message failed` whenever the client attempts to do its handshake.
Why would this be occurring?
server
```julia
function loopSecure(port, db)
server = Sockets.listen(port)
control_channel = Channel(10)
task = @async begin
while true
if(isready(control_channel))
val = take!(control_channel)
if(val == false)
break
end
end
conn = TCPSocket()
err = -1
while(err != 0)
err = Sockets.accept_nonblock(server,conn)
sleep(0.001)
end
@debug "Accepted " conn err
@async begin
@debug "Secure Connection Start"
entropy = MbedTLS.Entropy()
rng = MbedTLS.CtrDrbg()
MbedTLS.seed!(rng, entropy)
ctx = MbedTLS.SSLContext()
conf = MbedTLS.SSLConfig()
MbedTLS.config_defaults!(conf)
MbedTLS.authmode!(conf, MbedTLS.MBEDTLS_SSL_VERIFY_REQUIRED)
MbedTLS.rng!(conf, rng)
MbedTLS.ca_chain!(conf)
MbedTLS.setup!(ctx, conf)
MbedTLS.set_bio!(ctx, conn)
MbedTLS.handshake(ctx)
state = 0
time_start = 0
while true
if(processConnection(conn, db) )
state = 0
else
if(state == 0)
time_start = now()
state = 1
elseif(state == 1)
if(now() - time_start >= Minute(1))
@debug "Connection Timeout." conn
break
end
end
end
sleep(0.1)
end
end
end
close(server)
end
return server, control_channel
end
```
client
```julia
client=Sockets.connect(8081)
entropy = MbedTLS.Entropy()
rng = MbedTLS.CtrDrbg()
MbedTLS.seed!(rng, entropy)
ctx = MbedTLS.SSLContext()
conf = MbedTLS.SSLConfig()
MbedTLS.config_defaults!(conf)
MbedTLS.authmode!(conf, MbedTLS.MBEDTLS_SSL_VERIFY_REQUIRED)
MbedTLS.rng!(conf, rng)
MbedTLS.ca_chain!(conf)
MbedTLS.setup!(ctx, conf)
MbedTLS.set_bio!(ctx, client)
MbedTLS.handshake(ctx)
write(client,buffer)
flush(client)
tmp = readavailable(client)
```
---
### Author:  [@ligert123](https://discourse.julialang.org/u/ligert123)
#### Post date: [May 11, 2021, 1:43am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811/2 "2021-05-11T01:43:18Z")
Is anyone able to help or able to point me to someone who could?
---
### Author:  [@Sukera](https://discourse.julialang.org/u/Sukera)
#### Post date: [May 11, 2021, 5:31am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811/3 "2021-05-11T05:31:08Z")
At least on the client side, you’re writing to the wrong thing. MbedTLS does the writing to `client` for you, you just have to write to `ctx` after the handshake. See [the example from the README](https://juliahub.com/ui/Packages/MbedTLS/bf9T0/1.0.3) for details.
I haven’t used MbedTLS for the server side yet, but I think you’re making the same mistake there - passing `conn` instead of `ctx`.
* * *
Are you using the non-blocking busy loop for accepting the connection on purpose? Personally, I’d use a single task for accepting connections and just pass the resulting socket into a `Channel`, from which processing threads take and process the connection (including TLS etc).
---
### Author:  [@ligert123](https://discourse.julialang.org/u/ligert123)
#### Post date: [May 11, 2021, 6:37am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811/4 "2021-05-11T06:37:31Z")
Thanks for the feedback, yeah i found that issue but i seem to be having an issue during the handshake so it never actually reached that bit of code properly.
Also i was using it that way because the blocking was blocking other server threads. I do like that idea of using the channel though, that should make it able to scale better i feel which is important for this task.
I feel the server may need extra code or something but i didnt see any real examples other than the one readme one
---
### Author:  [@ligert123](https://discourse.julialang.org/u/ligert123)
#### Post date: [May 11, 2021, 7:06am UTC](https://discourse.julialang.org/t/usage-of-mbedtls-with-tcp-sockets/60811/5 "2021-05-11T07:06:56Z")
It seems to be a certificate issue, the SSLConfig needs to take in paths to a certificates public and private keys.
A certificate can be made on linux using `openssl req -x509 -nodes -newkey rsa:2048 -keyout selfsigned_client.key -out selfsigned_client.cert`
This will however not be able to work by default as it is not signed by a certificate authority, so you need to do `MbedTLS.authmode!(conf, MbedTLS.MBEDTLS_SSL_VERIFY_NONE)` after `conf = MbedTLS.SSLConfig()` to disable that check.
This should only be done for development purposes id assume though as its unsafe