# Logs Reference
> Flow Logs can be found in CloudWatch under the `DiscrimiNAT` log group, in the `flow` log stream. A typical flow log looks like:
## Fields
### flow logs
Flow Logs can be found in CloudWatch under the `DiscrimiNAT` log group, in the `flow` log stream. A typical flow log looks like:
Here's a summary of the possible fields:
`dhost`: destination hostname/FQDN or IP Address
`cat`: packet origin – client or server
`outcome`: allowed or disallowed
`src`: source IP address
`spt`: source port
`proto`: tls, ssh, http or unknown protocol
`proto_v`: version of the identified protocol
`dst`: destination IP address
`dpt`: destination port
`reason`: reason for the outcome – such as in which Security Group was a matching protocol rule found, cache not ready yet for a newly discovered allowlist entry, or which protocol anomaly led to the connection being disallowed
`instance`: the EC2 instance ID of the DiscrimiNAT instance this log line was generated from
`pqc`: indicates if a TLS handshake used a known [PQC TLS Supported Group](https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-8). The value may be true or false in case of TLS; or absent in the case of SSH.
If X.509 CRLs are [set to be allowed](/docs/discriminat/aws/default-prefs/#x509_crls), or if there is some plaintext HTTP egress traffic with requisite outbound ports open, there may be HTTP flow logs with the following fields. Note that HTTP is generally not allowed unless X.509 CRLs were allowed and the requested URL was of a CRL Endpoint.
`http_code`, `http_method`, `http_path`, `http_user_agent`: these fields can be useful to understand which application the plaintext HTTP traffic is originating from
And if a Security Group with a `see-thru` rule in it is found attached to a client application, the following fields will be also present:
`see_thru_days_remaining`: number of days remaining while the `see-thru` rule will be non-blocking, as defined in the `see-thru` rule itself
`see_thru_gid`: the Security Group ID where the `see-thru` rule was found, or _%default_ if set via [preferences](/docs/discriminat/aws/default-prefs/#see_thru)
`see_thru_exerted`: when _true_, the `see-thru` rule had to let this connection through and there was no protocol rule that would have allowed it; when _false_, there was a protocol rule that would have let the connection through anyway and its presence will be identified in the `reason` field; or the `see-thru` rule has expired
Watch this **4 minute video** to understand these three fields, and their interplay with the `outcome` field, when viewed in the Cloud web console.
Config reference for the `see-thru` rules can be found [here](/docs/discriminat/aws/config-ref#see-thru-mode).
### config logs
Config Logs can be found in CloudWatch under the `DiscrimiNAT` log group, in the `config` log stream. They form an audit trail of changes made to rules and Security Group attachments as clients come and go.
Here's a summary of the possible fields:
`cat`: fqdn (addr), wildcard pattern (wildcard-addr), client, see-thru or self change category
`outcome`: accepted something new in the internal configuration, removed something because it had been removed from external configuration sources, or rejected something (because of reason), or warning about a syntactically correct configuration input but one which wasn't going to work as expected (because of reason)
`client`: IP address of an affected client
`subnet`: block of IP addresses in the `a.b.c.d/e` notation of an affected subnet (mutually exclusive with `client`)
`gid`: the Security Group ID that relates to this change
`addr`: the FQDN, wildcard pattern or IP Address found in a Security Group rule
`proto`: tls or ssh protocol as identified in the rule
`reason`: reason for usually a warning or a rejected outcome
`instance`: the EC2 instance ID of the DiscrimiNAT instance this log line was generated from
If X.509 CRLs are [set to be allowed](/docs/discriminat/aws/default-prefs/#x509_crls) there will be an additional field:
`http_path`: the document path over HTTP for CRL data
And if a Security Group with a `see-thru` rule in it is found attached to a client application, there will be an additional field:
`thru_date`: the date until which the non-blocking `see-thru` mode should remain effective; past this date such a rule would lose effect
## Filters
The log lines are JSON-structured so each field can be addressed specifically. More of CloudWatch syntax can be explored on its [Filter and pattern syntax page](https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/FilterAndPatternSyntax.html).
#### _disallowed_ connections
`{ $.outcome = "disallowed" }`
#### _allowed_ but protocol is not TLS
`{ $.outcome = "allowed" && $.proto != "tls" }`
#### connections from a specific client where the destination host is not api.github.com
`{ $.cat = "client" && $.src = "172.16.1.9" && $.dhost != "api.github.com" }`
#### security groups where the see-thru mode exception has only 2 or less days left
`{ $.see_thru_days_remaining <= 2 }`
#### connections where the see-thru mode had to be used, but not for perhaps telemetry data
`{ $.see_thru_exerted is true && $.dhost != "ec2-instance-connect.*" }`
## Recipes
### building an allowlist from scratch (video version)
Watch this **3½ minute video** to build the allowlists super quick! The two commands used in the video are also documented here, underneath the video.
Command 1:
```
aws logs filter-log-events --output json --no-paginate --log-group-name DiscrimiNAT --log-stream-names flow --filter-pattern '{$.dhost != "" && $.see_thru_gid = '$SECURITY_GROUP_ID' && $.see_thru_exerted is true}' --start-time $(date --date '2 hours ago' +%s000) | jq '[.events[].message | fromjson]' | dd of=frequency-fqdns.json
```
Command 2:
```
cat frequency-fqdns.json | jq --raw-output 'group_by(.dhost) | map(.[0] + {"count": length}) | sort_by(.count) | reverse | [.[].dhost] | @csv' | tr --delete '"'
```
### building an allowlist from scratch (text version)
:::info
This method is now deprecated in favour of the CloudShell based method above.
:::
1. Create a new Security Group, with a `see-thru` rule in it. See the config reference and an example [here](/docs/discriminat/aws/config-ref#see-thru-mode). Give it a thru date sufficient enough to capture all stages of the application's lifecycle, such as deployment, restart, the occassional uploading of reports, telemetry, monitoring, etc. Note the Security Group ID.
2. Attach this Security Group to the application. In AWS this could be either attaching the Security Group to the EC2 instances in addition to other attachments, or in the case of serverless workloads, to the Network Interface (ENI) that is in the VPC.
3. Let the application follow its normal course of lifecycle. This could last a few hours, days or weeks depending on the application.
4. Go to **CloudWatch Log Insights** and select the DiscrimiNAT log group. Then enter the following query, select an appropriate time range, and run it. _Note: You'll have to replace the Security Group ID in this example with the one that was created above._
```
filter see_thru_exerted AND see_thru_gid = "sg-00replaceme00"
| stats count() by see_thru_exerted, see_thru_gid, dhost, proto, dpt
```
This will produce a table of results like:
5. From the information in the results table, specific allowlist protocol rules can be created. For example:
`discriminat:tls:ec2.us-west-2.amazonaws.com,ssm.us-west-2.amazonaws.com`
and `discriminat:tls:api.github.com` with protocol TCP and destination port 443.
Full reference for creating these protocol rules is [here](/docs/discriminat/aws/config-ref#tls-and-ssh-mode).
6. Once these protocol rules are attached to the application, run the full application lifecycle again, and then the query at #4 to ensure that `see_thru_exerted` did not have to be used to let any disallowed traffic through. There may be the case where you choose to disallow certain destinations anyway, such as endpoints that just collect telemetry data.
7. Detach or remove the `see-thru` rule from the application and give it another full lifecycle run to ensure it works smoothly.