Now, there's also a dockerized Signal Web Gateway
I have already wrote a basic check_mk Signal notification plugin. But now, i needed more clients to send messages and don't want to register multiple numbers. So this is a basic gateway which delivers messages via SSH.
Go and get janimo's Textsecure client. Check his wiki on how to get a working binary.
As SSH adds an authentication and encryption layer to the whole thing, i'm using it with authorized key files. I'd recommend a special user for this, probably best called signal or axolotl (the Signal protocol, sounds more fancy 😄) or similiar.
useradd -s /bin/bash -m -d /opt/signal-gateway axolotl
Now, create the authorized_keys file:
su - axolotl
mkdir -m 700 .ssh
(umask 077; touch .ssh/authorized_keys)
Now you need to add the public keys of the systems/users using this gateway.
As the newly created user, clone this project:
su - axolotl
git clone https://github.com/morph027/signal-gateway
Please follow janimo's wiki on how to setup the client properly. You then need to put the binary, the .config and .storage into the bin folder of this project. Rename textsecure to signal (or create a softlink).
ssh [-i /your/ssh/folder/id_rsa_or_so] user@yourserver /folder/to/signal-gateway/bin/signal-wrapper --from someone --to account.from.your.signal.address.book.or.phone.number --message \"this is your message\"
You need to set the hexid (see .storage/groups/${hexid}) of the group as --to.
To add messages to s simple queue (in case of internet failures), you can pass --queue. Basically, the messages will be added to a text file which will then be read by a script later (e.g. fired by cron).
Cron: crontab -u user -e and then add */5 * * * * /folder/to/signal-gateway/bin/signal-resend