The Tool Desk
Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Secure Roundcube by treating it as a public web application and an authentication gateway: patch Ubuntu and Roundcube, publish only the public_html directory over HTTPS, keep PHP errors and private directories out of the browser, preserve TLS certificate validation for mail connections, and use Fail2ban to slow repeated login attacks.
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The exact package command depends on your Ubuntu release and whether Roundcube came from Ubuntu packages or an upstream archive. The following procedure keeps those differences explicit so you can verify versions before changing a production server.
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Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problems1. Define the security boundary before changing anything
Roundcube is not the mail server. It is a PHP web application that talks to IMAP, SMTP and, optionally, ManageSieve. A compromise can expose mailbox credentials, sessions, address books and message content, while a weak mail-server TLS setting can expose credentials even when the browser connection is encrypted. Harden all three paths: browser to web server, web server to Roundcube, and Roundcube to the mail services.
Record the current deployment
- Identify the Ubuntu release with
cat /etc/os-releaseand note whether it is an LTS release, an interim release or an end-of-support system. - Find the installed package and version with
apt policy roundcube-core. An upstream installation may not appear in APT; record its filesystem location and release number separately. - Record the web server (Apache or Nginx), PHP version and PHP-FPM service, the actual Roundcube
errors.logpath, and the IMAP, SMTP and ManageSieve hostnames. - Back up Roundcube configuration, its database and mail-server settings. Test that the backup can be restored before editing access controls.
Do not copy a command for one Ubuntu release onto another. Corrected package versions, repository availability and Ubuntu Pro coverage differ by release.
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2. Patch Ubuntu and Roundcube continuously
Roundcube published security releases 1.6.19 and 1.7.4 on 6 September 2026. The Roundcube Project said both versions fixed recently reported security vulnerabilities. Treat that date as a release milestone, not as permission to stop updating: later fixes can supersede them.
Use Ubuntu packages where they fit your deployment
- Refresh package metadata:
sudo apt update. - Review pending security upgrades rather than blindly accepting every change:
apt list --upgradableandapt policy roundcube-core. - Apply the tested changes during a maintenance window:
sudo apt upgrade. If the resolver requires dependency changes, review the transaction before usingsudo apt full-upgrade. - Confirm the resulting package:
dpkg-query -W -f='${Package} ${Version}n' roundcube-core. - Restart only the services that changed, then test login, reading mail, sending mail and logout. A PHP or web-server update may require a PHP-FPM or web-server restart.
Canonical describes Ubuntu as a fixed-release distribution whose supported releases receive security fixes as backported patches. Since Ubuntu 18.04 LTS, unattended-upgrades has been included in default Desktop and Server installations and applies security updates daily by default. Verify that it is enabled instead of assuming it is:
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Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →sudo systemctl status unattended-upgrades
sudo unattended-upgrade --dry-run --debugAutomatic updates do not replace review. Subscribe to Ubuntu Security Notices, inspect held packages, and schedule a monthly verification that the installed Roundcube version is still supported.
Check release-specific advisories
USN-8097-1 lists corrected Roundcube packages by Ubuntu release. One listed example is Ubuntu 24.04’s roundcube-core 1.6.6+dfsg-2ubuntu0.1+esm2; several corrected builds are available through Ubuntu Pro. That value is advisory evidence, not a universal target. Check the live notice and your release’s package candidate before making a change:
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apt-cache policy roundcube-core
apt changelog roundcube-coreUbuntu LTS releases receive five years of standard security maintenance for the Main and Restricted components. Longer coverage requires Ubuntu Pro according to Canonical’s support table. An unsupported Ubuntu release should be upgraded; extending an exposed webmail host with an unmaintained operating system is not a hardening strategy.
3. Publish only Roundcube’s intended public directory
The upstream installation guide requires the HTTP server’s document root to point to Roundcube’s public_html directory. This prevents configuration files, SQL schema files, logs and temporary data from being downloaded if a web-server rule is missed.
Verify the filesystem layout
- Locate the Roundcube tree and identify its
public_html,config,logsandtempdirectories. - Set the virtual host’s document root to
public_html, not the parent directory. - Remove or disable the installer after setup. If an installer endpoint is still present, restrict it to an administrative network or delete it according to the package’s upgrade procedure.
- Make application files owned by root or the package manager where practical. Grant the web-server user write access only to the required
logsandtempdirectories. - Check the effective web-server configuration and test that requests for configuration files, database dumps, logs and temporary files return a denial or a not-found response.
Do not solve a permissions problem by making the entire Roundcube tree writable by the web-server user. That turns a web vulnerability into an application-wide file-modification capability.
4. Force HTTPS safely
Serve the login page and every authenticated request over HTTPS. Configure the HTTP virtual host to redirect to the canonical HTTPS hostname, then test that no alternate hostname, port or subdomain still serves a login form without TLS.
Apache and Nginx choice
| Decision factor | Apache | Nginx |
|---|---|---|
| Best fit | Existing Apache stack and teams comfortable with virtual-host and module configuration | Existing Nginx stack, especially where PHP-FPM is already standard |
| PHP integration | Use the selected PHP handler; avoid exposing source files when changing handlers | Pass only PHP requests to PHP-FPM and deny direct access to hidden or private paths |
| TLS automation | Use the ACME-capable automation already approved for the host | Use the ACME-capable automation already approved for the host |
| Logging | Review access and error logs alongside Roundcube’s application log | Review access and error logs alongside Roundcube’s application log |
The important control is not the server brand. It is a valid certificate, a complete trust chain, a private key readable only by the TLS service, and a redirect that covers every HTTP entry point.
Add HSTS only after TLS is complete
HSTS tells browsers to refuse HTTP. Enable it only after every required hostname and subdomain works over TLS, certificates renew automatically, and no legitimate service depends on HTTP. A mistaken HSTS policy can lock administrators out until the browser policy expires or is cleared.
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5. Keep PHP diagnostics from becoming an information leak
Roundcube’s installation guide states that it forces display_errors=Off and log_errors=On. Preserve that behavior in the effective PHP configuration and confirm it after PHP upgrades. Browser-visible warnings can disclose filesystem paths, SQL details, usernames and mail-server names.
Protect logs and temporary data
- Keep
errors.logoutside the public document root, or explicitly deny direct web access if the package stores it beneath the application tree. - Allow the web-server user to write the
logsandtempdirectories, but do not grant write access to configuration or code directories. - Set restrictive permissions on logs because they can contain usernames, IP addresses and authentication-failure details.
- Rotate logs and monitor disk usage. A full filesystem can break both login and security logging.
- Check that PHP-FPM and the web server send errors to controlled logs rather than to the response body.
After changing PHP or the web server, deliberately request a harmless missing page and inspect the response and logs. The browser should receive a generic error; diagnostic detail should appear only in protected logs.
6. Preserve certificate validation for IMAP, SMTP and ManageSieve
Roundcube’s documentation says PHP validates SSL certificates by default. A self-signed certificate or a certificate whose name does not match the configured host produces a connection error. That error is a configuration problem, not a reason to disable verification.
Fix the cause of a TLS failure
- Use the mail service’s DNS name that appears in its certificate’s Subject Alternative Name.
- Install the issuing CA chain on Ubuntu when an organization uses a private but trusted CA.
- Renew expired certificates and correct incomplete intermediate-chain delivery on the IMAP or SMTP service.
- Check system time; a badly skewed clock can make a valid certificate appear expired or not-yet-valid.
- Confirm that the configured port and encryption mode match the service (implicit TLS versus STARTTLS).
Roundcube exposes correctly scoped connection settings through imap_conn_options, smtp_conn_options and managesieve_conn_options. Use those settings to express the required hostname, CA or transport options for the specific service. Do not set a global option that accepts any certificate, and do not use a blanket “no verification” workaround in production.
7. Stop repeated login attacks with Fail2ban
Ubuntu publishes roundcube-plugin-fail2ban in the Universe repository. It depends on roundcube-core and recommends fail2ban; the package is intended to ban hosts that cause multiple authentication errors.
Install and connect the integration
- Enable the repository approved for your Ubuntu release, then install the packages:
sudo apt updatefollowed bysudo apt install roundcube-plugin-fail2ban fail2ban. - Find the actual Roundcube error log. Common package layouts differ, so do not assume a path. Confirm that failed authentication events are written there.
- Enable the supplied
roundcube-authjail in a local Fail2ban configuration file rather than editing the vendor’sjail.conf. - Set
logpathto the realerrors.log, list the HTTP and HTTPS ports used by the site, and choose conservative retry and ban intervals. - Validate the configuration, restart Fail2ban and inspect its status.
sudo fail2ban-client -t
sudo systemctl restart fail2ban
sudo fail2ban-client status roundcube-authFail2ban’s upstream configuration includes a [roundcube-auth] jail with HTTP/HTTPS ports, and its dedicated filter parses Roundcube authentication events. Names and paths can differ between package revisions, so inspect the installed filter and jail files before enabling them.
Choose thresholds deliberately
| Setting | Stronger protection | Lower false-positive risk |
|---|---|---|
| maxretry | Fewer failed attempts before a ban | More failed attempts allowed |
| findtime | Short window catches rapid guessing | Longer window can reduce accidental bans when paired with a higher retry count |
| bantime | Longer block frustrates persistent attacks | Shorter block eases recovery from a mistaken ban |
| Operational visibility | Review bans, unbans and matched log lines frequently | At minimum, alert on repeated bans and authentication spikes |
Start with a staging account, not a production administrator. Generate a controlled failed-login sequence, confirm the filter matches the event, verify that the expected address is banned, then unban it. Exclude trusted monitoring or administrative source addresses only when you can protect those networks by other means; broad exclusions create an attacker bypass.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.8. Package-managed versus upstream Roundcube
| Consideration | Ubuntu package | Upstream installation |
|---|---|---|
| Update cadence | Integrated with Ubuntu security maintenance and release-specific advisories | Tracks Roundcube releases directly; administrators must monitor and deploy them |
| Filesystem layout | Follows Debian/Ubuntu conventions and package ownership | Layout is chosen during installation; document-root and writable-directory mistakes are easier to make |
| Rollback | Use package history, snapshots and database backups | Keep the previous application tree and database-compatible backup before replacing files |
| Ubuntu Pro | Some corrected builds may be available through Pro, depending on release | Pro does not patch an independently installed upstream tree |
Neither method is automatically safer. Choose the one your team can patch, monitor and roll back reliably. Do not mix package-managed files with an independently copied application tree without documenting ownership and upgrade order.
9. Test the finished hardening
- Browser transport: HTTP redirects to HTTPS; the certificate name, validity period and chain are correct; authenticated pages never load over HTTP.
- Exposure: Only
public_htmlis reachable; installer, configuration, logs and temporary files are denied. - Diagnostics: PHP errors are not displayed; Roundcube errors are logged; log permissions prevent public reading.
- Mail TLS: IMAP, SMTP and ManageSieve connections validate certificates and use the expected hostnames and ports.
- Brute-force control: The Fail2ban filter matches a real failed login, applies a ban at the configured threshold and records the event.
- Recovery: An authorized administrator can remove a mistaken ban, restore configuration and roll back a failed package update.
10. Troubleshooting common failures
| Symptom | Likely cause | Safe corrective action |
|---|---|---|
| APT shows no Roundcube security update | Wrong Ubuntu release, stale metadata, held package or upstream installation | Check /etc/os-release, run apt update, inspect apt policy and identify the installation source before changing repositories |
| Roundcube displays a PHP warning | Effective PHP configuration overrides the application’s setting | Check PHP-FPM and web-server configuration, restore display_errors=Off, keep log_errors=On, then restart the affected service |
| Users cannot log in after TLS hardening | Mail certificate hostname, CA chain, clock or encryption mode is wrong | Fix the certificate or hostname and use the scoped connection options; do not disable verification |
| Fail2ban never bans | Wrong log path, filter mismatch, unreadable log or inactive jail | Use fail2ban-client status roundcube-auth, inspect matched lines and correct logpath or the installed filter |
| Legitimate users are banned | Thresholds are too aggressive or a shared NAT address is generating failures | Unban the address, raise the retry threshold or adjust the window, and monitor before tightening again |
| Renewed certificate still fails in browsers | Incomplete chain, wrong virtual host or stale service configuration | Verify the served certificate on the canonical hostname and reload the web server after renewal |
11. A maintenance schedule that keeps the controls working
Every day
- Let unattended security upgrades run and alert on failures.
- Watch web-server, Roundcube and Fail2ban logs for authentication spikes, unusual status codes and repeated bans.
Every month
- Review Ubuntu and Roundcube advisories, installed versions and held packages.
- Test a backup restore and confirm that log rotation has not stopped security logging.
- Check certificate expiry, renewal automation and all hostnames covered by HSTS.
After every upgrade
- Verify the effective document root, PHP error settings, writable-directory permissions and Fail2ban jail status.
- Perform a complete browser login, IMAP read, SMTP send and logout test.
- Record the package version, configuration change and rollback point.
The Bottom Line
A secure Roundcube deployment is maintained, not merely configured once: keep Ubuntu and Roundcube patched, expose only public_html over correctly validated HTTPS, protect logs and temporary files, retain certificate verification for mail protocols, and continuously test the Fail2ban and recovery paths.
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