Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

tls: Add descriptions for x509v3 alt name verification (tls.verify_hostname) #1393

Merged
merged 3 commits into from
Jun 27, 2024
Merged

tls: Add descriptions for x509v3 alt name verification (tls.verify_hostname) #1393

Show file tree
Hide file tree
Changes from 2 commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
2862e2a
tls: Add a description for tls.verify_hostname parameter
cosmo0920 Jun 17, 2024
6c3f5d0
filter_kubernetes: Add a description for tls.verify_hostname
cosmo0920 Jun 17, 2024
bcfc9de
Address comments
cosmo0920 Jun 21, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
39 changes: 39 additions & 0 deletions administration/transport-security.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ Both input and output plugins that perform Network I/O can optionally enable TLS
| :--- | :--- | :--- |
| tls | enable or disable TLS support | Off |
| tls.verify | force certificate validation | On |
| tls.verify\_hostname | force hostname validation for certificates | Off |
Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Slightly different wording to below.

| tls.debug | Set TLS debug verbosity level. It accept the following values: 0 \(No debug\), 1 \(Error\), 2 \(State change\), 3 \(Informational\) and 4 Verbose | 1 |
| tls.ca\_file | absolute path to CA certificate file | |
| tls.ca\_path | absolute path to scan for certificate files | |
Expand Down Expand Up @@ -171,3 +172,41 @@ Fluent Bit supports [TLS server name indication](https://en.wikipedia.org/wiki/S
tls.ca_file /etc/certs/fluent.crt
tls.vhost fluent.example.com
```

### Verify subjectAltName

When extracting the X509v3 Subject Alternative Name from a certificate:
cosmo0920 marked this conversation as resolved.
Show resolved Hide resolved

```
X509v3 Subject Alternative Name:
DNS:my.fluent-aggregator.net
```

Then, the TLS client will connect to `other.fluent-aggregator.net`, there is a glitch of hostnames.
cosmo0920 marked this conversation as resolved.
Show resolved Hide resolved

This difference of the hostname can be detected with:
cosmo0920 marked this conversation as resolved.
Show resolved Hide resolved


```text
[INPUT]
Name cpu
Tag cpu

[OUTPUT]
Name forward
Match *
Host other.fluent-aggregator.net
Port 24224
tls On
tls.verify On
tls.verify_hostname on
tls.ca_file /path/to/fluent-x509v3-alt-name.crt
```

This outgoing connect will be failed and disconnected:

```
[2024/06/17 16:51:31] [error] [tls] error: unexpected EOF with reason: certificate verify failed
[2024/06/17 16:51:31] [debug] [upstream] connection #50 failed to other.fluent-aggregator.net:24224
[2024/06/17 16:51:31] [error] [output:forward:forward.0] no upstream connections available
```
1 change: 1 addition & 0 deletions pipeline/filters/kubernetes.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,7 @@ The plugin supports the following configuration parameters:
| Keep\_Log | When `Keep_Log` is disabled, the `log` field is removed from the incoming message once it has been successfully merged \(`Merge_Log` must be enabled as well\). | On |
| tls.debug | Debug level between 0 \(nothing\) and 4 \(every detail\). | -1 |
| tls.verify | When enabled, turns on certificate validation when connecting to the Kubernetes API server. | On |
| tls.verify\_hostname | When enabled, turns on hostname validation for certificates | Off |
| Use\_Journal | When enabled, the filter reads logs coming in Journald format. | Off |
| Cache\_Use\_Docker\_Id | When enabled, metadata will be fetched from K8s when docker\_id is changed. | Off |
| Regex\_Parser | Set an alternative Parser to process record Tag and extract pod\_name, namespace\_name, container\_name and docker\_id. The parser must be registered in a [parsers file](https://github.com/fluent/fluent-bit/blob/master/conf/parsers.conf) \(refer to parser _filter-kube-test_ as an example\). | |
Expand Down