The article suggests that if an application goes
on the internet by another protocol than tcp, then tor
cannot catch the data traffic. Does delta chat transfer
internet data by other protocols than tcp?
Wrongfully I thought proxychains would force
any application to transfer data over tor. Or deny the data
transfer. That is not the case. Cf jami.
If you select the socks5 option in delta chat it says if you type in an address in the email field there will be dns lookup that wont get tunneled through socks5.
proxychains support proxy dns. Whether proxychains will catch
dns requests made by delta chat I cannot say.
Most of the times Delta Chat connects to the email server using IMAP and submits messages using SMTP. These protocols work over TCP. These protocols should be caught with torsocks, and they are also proxied when you configure the SOCKS 5 option inside the application itself.
During the initial configuration Delta Chat also does HTTPS requests to the email server to check for the autoconfiguration XML. These requests also use TCP and are proxied over SOCKS 5.
What is not proxied is the DNS query for the MX record:
This is the DNS lookup that you are talking about. It is skipped if you enable the SOCKS5 setting, but the problem is that SOCKS5 setting is actually enabled only once you click “configure”. A solution could be to have a screen where you can enable SOCKS5 before the screen where you enter the email address, but this is not the current state of the UI.
This DNS lookup uses external library trust_dns_resolver and I cannot for sure say whether it uses TCP or UDP for DNS requests, the library even contains multiple resolver implementation for multiple operating systems.
One thing that uses UDP is an “Add as second device” option, it is based on iroh library which uses QUIC interally. This is not proxied and the QR code contains local IP address so one device can discover the other on the local network. This should not be a concern though, because it does not make any requests to any servers, even relays. This may change if iroh introduces UDP holepunching to deal with cases where your devices are on different networks, but you don’t have to use this feature and indeed better avoid using it in a torified setup.