Why is Exim installed, firewall configuration, how to change the turn port?

bestman · December 13, 2025, 8:07pm

Hi all, thanks for your help, read the documentation and have a couple of questions:

As I can see, Exim is also installed on the Debian server, although I don’t see it in the running ones, why is it installed?

ls /etc/exim4/
conf.d  exim4.conf.template  passwd.client  update-exim4.conf.conf

Setting up a firewall as I see from the documentation and ports that are now open, I think it looks like this(please correct if I’m missing something)

# SSH
ufw allow 22/tcp comment 'ssh'
# Nginx HTTP/HTTPS
ufw allow 80/tcp comment 'nginx http'
ufw allow 443/tcp comment 'nginx https'
# turn UDP
ufw allow 3478/udp comment 'coturn udp'
# turn 
ufw allow 49152:65535/ comment `udp call`
# Mail
ufw allow 587/tcp comment 'mail'
ufw allow 465/tcp comment 'mail'
ufw allow 993/tcp comment 'mail'
ufw allow 25/tcp comment 'mail'
ufw allow 143/tcp  comment `open it??'
ufw enable

Can I change the server’s turn port to 5478, for example?
Did not find where the turn server is installed, as well as its configuration file?

WofWca · December 14, 2025, 7:04am

No, currently it’s hard-coded, but I don’t recall a particular reason for that having to be the case, except maybe this.

github.com/chatmail/relay

chatmaild/src/chatmaild/metadata.py

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          elif keyname == "vendor/vendor.dovecot/pvt/server/vendor/deltachat/turn":
              res = turn_credentials()
              port = 3478
              return f"O{self.turn_hostname}:{port}:{res}\n"

github.com/chatmail/chatmail-turn

src/main.rs

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          let port = 3478;
          let realm = matches.value_of("realm").unwrap();
          let socket_path = Path::new(matches.value_of("socket").unwrap());

It’s installed to /usr/local/bin/chatmail-turn:

github.com/chatmail/relay

cmdeploy/src/cmdeploy/deployers.py

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          commands=[
              f"(curl -L {url} >/usr/local/bin/chatmail-turn.new && (echo '{sha256sum} /usr/local/bin/chatmail-turn.new' | sha256sum -c) && mv /usr/local/bin/chatmail-turn.new /usr/local/bin/chatmail-turn)",
              "chmod 755 /usr/local/bin/chatmail-turn",
          ],

And then launched from here:

github.com/chatmail/relay

cmdeploy/src/cmdeploy/service/turnserver.service.f

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          [Unit]
          Description=A wrapper for the TURN server
          After=network.target
          
          [Service]
          Type=simple
          Restart=always
          ExecStart=/usr/local/bin/chatmail-turn --realm {mail_domain} --socket /run/chatmail-turn/turn.socket
          
          # Create /run/chatmail-turn
          RuntimeDirectory=chatmail-turn
          User=vmail
          Group=vmail
          
          [Install]
          WantedBy=multi-user.target

There is nothing to configure currently

github.com/chatmail/chatmail-turn

src/main.rs

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          .arg(
              Arg::with_name("realm")
                  .default_value("webrtc.rs")
                  .takes_value(true)
                  .long("realm")
                  .help("Realm (defaults to \"webrtc.rs\")"),
          )
          .arg(
              Arg::with_name("socket")
                  .required(true)
                  .takes_value(true)
                  .long("socket")
                  .help("Unix socket path"),
          );