diff --git a/proxy/README.md b/proxy/README.md index 946c749..fa80a9d 100644 --- a/proxy/README.md +++ b/proxy/README.md @@ -60,3 +60,42 @@ sudo ufw delete allow 22/tcp - Access NPM admin: `https://proxy..ts.net` - Default credentials: `admin@example.com` / `changeme` - Optionally approve exit-node in Tailscale admin console + +## Centralized log reception (rsyslog) + +A fail2ban jail running inside an exposed service's own LXC only ever sees +this proxy's tailnet IP as the connection source, so it would end up +banning the proxy itself instead of the actual client. Detection has to +stay where the signal is (the service's application log); banning has to +happen here, where public connections terminate. Services forward their +logs to this proxy over TCP so a jail here can act on them. + +| File | Purpose | +|------|---------| +| `/etc/rsyslog.d/10-remote-receiver.conf` | Generic `imtcp` listener, port `RSYSLOG_PORT` (default `5514`). Anything not claimed by a more specific routing file lands in `/var/log/remote/.log`. | +| `/etc/rsyslog.d/50-.conf` | One per exposed service. Routes by tag/programname into that service's own logfile for its dedicated fail2ban jail. | +| `/etc/logrotate.d/remote-logs` | Rotation for everything under `/var/log/remote/` (`copytruncate`, so fail2ban never loses its file descriptor across a rotation). | + +Adding a new exposed service is a matter of dropping its `50-.conf` +here — nothing else in this list needs to change. A minimal example that +routes messages tagged `myservice` into their own file, in addition to the +generic catch-all: + +``` +$RuleSet remoteLogs +if $programname == 'myservice' then { + action(type="omfile" file="/var/log/myservice/myservice.log") +} +$RuleSet RSYSLOG_DefaultRuleset +``` + +`RSYSLOG_PORT` and `RSYSLOG_BIND_ADDR` (default `0.0.0.0`) are overridable +via environment. The default bind is safe as-is: UFW's default-deny only +opens `80/tcp` and `443/tcp` publicly, so port `5514` is reachable +exclusively over `tailscale0` regardless of the bind address. Binding to +the tailnet IP directly was considered and rejected — it would require +`tailscale up` to have already succeeded before rsyslog is configured, +which complicates the script's flow (a missing `TS_AUTHKEY` is tolerated +today). The residual risk is log injection from anything that reaches the +port (which can trigger a false fail2ban ban); narrow `RSYSLOG_BIND_ADDR` +to a specific tailnet IP if that risk becomes a concern. diff --git a/proxy/install.sh b/proxy/install.sh index cfca993..b2b498a 100644 --- a/proxy/install.sh +++ b/proxy/install.sh @@ -44,6 +44,13 @@ ACME_EMAIL="${ACME_EMAIL:-}" # Generate at https://login.tailscale.com/admin/settings/keys TS_AUTHKEY="${TS_AUTHKEY:-}" +# rsyslog receiver for exposed services' logs (see "Configuring rsyslog" below). +RSYSLOG_PORT="${RSYSLOG_PORT:-5514}" +# Default 0.0.0.0 is fine: UFW's default-deny only opens 80/443 publicly, so +# this port is reachable exclusively over tailscale0 either way. Override to +# a specific tailnet IP to shrink the blast radius of log injection instead. +RSYSLOG_BIND_ADDR="${RSYSLOG_BIND_ADDR:-0.0.0.0}" + main() { log_info "=== Proxy Server Deployment (Traefik v3) ===" @@ -75,7 +82,7 @@ main() { log_info "Installing base packages..." sudo apt update -qq - sudo apt install -y -qq vim ca-certificates curl gnupg lsb-release fail2ban unattended-upgrades ufw ethtool networkd-dispatcher > /dev/null + sudo apt install -y -qq vim ca-certificates curl gnupg lsb-release fail2ban unattended-upgrades ufw ethtool networkd-dispatcher rsyslog > /dev/null log_info "Installing Tailscale..." curl -fsSL https://tailscale.com/install.sh | sh @@ -174,6 +181,40 @@ EOF sudo systemctl restart fail2ban + log_info "Configuring rsyslog receiver for exposed services..." + # A fail2ban jail running inside a service's own LXC only ever sees this + # proxy's tailnet IP as the source of connections, so it would end up + # banning the proxy itself. Detection has to stay where the signal is + # (the service's application log); banning has to happen here, at the + # edge where public connections actually terminate. Services forward + # their logs to this receiver over TCP; adding a new one is a matter of + # dropping a 50-.conf here (see proxy/README.md) — nothing else + # to touch. + sudo mkdir -p /var/log/remote + sudo tee /etc/rsyslog.d/10-remote-receiver.conf > /dev/null << EOF +module(load="imtcp") + +\$RuleSet remoteLogs +\$template RemoteLogPath,"/var/log/remote/%HOSTNAME%.log" +*.* ?RemoteLogPath +\$RuleSet RSYSLOG_DefaultRuleset + +input(type="imtcp" port="${RSYSLOG_PORT}" address="${RSYSLOG_BIND_ADDR}" ruleset="remoteLogs") +EOF + + sudo tee /etc/logrotate.d/remote-logs > /dev/null << 'EOF' +/var/log/remote/*.log { + daily + rotate 7 + compress + missingok + notifempty + copytruncate +} +EOF + + sudo systemctl restart rsyslog + log_info "Creating Traefik stack under $TRAEFIK_DIR..." mkdir -p "$TRAEFIK_DIR/conf.d"