no way to compare when less than two revisions
Differences
This shows you the differences between two versions of the page.
| — | fetch_mail_via_ssh_from_a_remote_server_and_send_them_via_a_mail_account_to_someone [26.05.2021 19:07] (current) – created Pascal Suter | ||
|---|---|---|---|
| Line 1: | Line 1: | ||
| + | ====== fetch mail via SSH from a remote server and send them via a mail account to someone ====== | ||
| + | suppose you have a server somewhere in a very restricted network. there is no way for you to send emails to your regular mail account in order to receive alerts such as Disk failures, backup reports etc... BUT: you have ssh access :) | ||
| + | you could setup a reverse tunnel to an smtp server somehwere, but your restricted network might not like long lasting ssh connections and kick you out all the time.. so here is a solution, where a linux machine with SSH access to your cut-off server can collect mails on that server and then forward it to a smtp server for delivery. | ||
| + | |||
| + | in my example, i deliberately change the FROM and TO header fields to always point to my own mail addres, as i want to be the sole recipient of all mails from this server and my SMTP allows only my own email address as a sender address.. you can adjust that to be a full blown mail realyer .. but be carefule what you wish for ;) | ||
| + | |||
| + | ===== Prerequisites ===== | ||
| + | besides ssh we also need msmtp and formail. the latter is part of the procmail package in ubuntu: | ||
| + | sudo apt install procmail msmtp | ||
| + | |||
| + | setup password less ssh access as the user who's mail you want to fetch from the target server | ||
| + | |||
| + | create a directory tree for our mail fetcher app | ||
| + | < | ||
| + | mailfetcher/ | ||
| + | ├── mailfetcher.sh | ||
| + | ├── .msmtprc | ||
| + | └── outbox | ||
| + | </ | ||
| + | |||
| + | write that '' | ||
| + | |||
| + | <code conf .msmtprc> | ||
| + | account default | ||
| + | host my.mail.server | ||
| + | port 587 | ||
| + | tls on | ||
| + | tls_starttls on | ||
| + | tls_trust_file / | ||
| + | tls_certcheck on | ||
| + | auth on | ||
| + | user my_Mail_user | ||
| + | password " | ||
| + | from " | ||
| + | </ | ||
| + | make sure to put the right values in there for your mail account :) | ||
| + | |||
| + | ===== The Script ===== | ||
| + | the script below will connect to your server, fetch all mails from ''/ | ||
| + | it will then start a loop where it goes through all downloaded messages and sends them via msmtp. | ||
| + | <code bash mailfetcher.sh> | ||
| + | #!/bin/bash | ||
| + | MYPATH=$(dirname " | ||
| + | cd $MYPATH | ||
| + | |||
| + | user=" | ||
| + | server=" | ||
| + | mail=" | ||
| + | |||
| + | ssh ${user}@${server} cat / | ||
| + | FILENO=$(date +%s001) \ | ||
| + | formail -i "To: $mail" -k -R From: Old-From: -X Subject: -X Date: -X To: -X Old-To: -ds sh -c \ | ||
| + | 'cat > outbox/ | ||
| + | ssh ${user}@${server} 'echo "" | ||
| + | for msg in outbox/ | ||
| + | cat $msg | msmtp -C .msmtprc -t -v && rm -f $msg | ||
| + | sleep 15 | ||
| + | done | ||
| + | </ | ||
| + | |||
| + | fill the first variables with the right content ;) | ||
| + | |||
| + | make the script executable: | ||
| + | chmod 755 mailfetcher.sh | ||
| + | |||
| + | ===== testing and cron job ===== | ||
| + | to test the script, simply run it from a shell, it will print verbose output from the smtp sessions. if you run into message rate limit issues, increase the time for the '' | ||
| + | |||
| + | once you are satisfied, set up a cron job.. | ||
| + | crontab -e | ||
| + | here is an example where we run the script once per hour to fetch mail and deliver it.. Headline | ||
| + | 00 * * * * / | ||