Syslog Explained (Facilities and Severities)

This is an original planning guide. It is not a vendor manual, an official standard, or legal advice. Example addresses use documentation ranges. Review every command before you paste it.

What this hour is for

The PRI is a number that packs facility and severity. The parser and the calculator explain a line you paste. They do not receive syslog. A severity is how loud the sender thought the event was, not proof of an incident.

Paste one line you are allowed to hold. Redact hostnames that are sensitive and any token. Forwarding is a later ticket, toward a collector you administer. Do not point a device at a collector you do not run.

One line. The security desk's log work stays a sentence, not a second project.

The change you can finish

Apply nothing during the writing of the note. When the lab window opens, it is one change on the device named in the ticket. Read the draft, then the device, then decide.

Rollback is the file or the revision you saved first. You do not invent a rollback after the only copy is gone.

Paste one line you may hold.
Read facility and severity.
Redact tokens.
Do not add a forwarder.
Do not send the line to a collector you do not run.
Stop.

Mistakes that outlive the command

Syslog Explained (Facilities and Severities) goes wrong in a small set of ways. The list is here so the ticket can forbid them before the window.

A forwarder aimed at a stranger.
A token left in the note.
Severity called an incident by itself.
A device you do not administer changed to emit logs.

Decisions to write down

One decision for Syslog Explained (Facilities and Severities): The line is yours to hold. Facility and severity are written. No forwarder was added. Tokens are gone. And the collector, if named, is yours.

Checks before you call it done

Confirm this before you call the change done: The PRI is written. Facility and severity are written. No token remains. No forwarder was configured. And no foreign collector was named. If one of those fails, stop.

Before you leave the device

Syslog Explained (Facilities and Severities) ends when the hostname on the device matches the hostname in the ticket. If it does not, you are on the wrong box. Stop. A command that succeeded on the wrong box is not progress.

The draft stays a draft until a person has read the names in it. A generator does not log into the device and does not know which interface is the uplink. You delete a line that names a device, a zone, or a prefix you did not write down.

0.0.0.0/0 is not kept because a sample included it. A source you can say is the source you keep. 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, and 2001:db8::/32 are documentation. They belong in the note. They are not prefixes you type onto a production device because they appeared in a draft.

prompt-for-this is a reminder that a secret is missing. It is not a password, a key, a community string, or a pre-shared key you save in the ticket or in git. The real secret stays in the store.

One change is the window. A VLAN and a routing protocol and a VPN do not share it. If two things move and the result is wrong, you will not know which one did it. The next feature waits for its own page.

If the same step fails twice, stop for the day. The failure is the result. Adding a forum command beside a half-applied config produces a device nobody can rebuild. Restore the copy you took first.

A second person reads the device name and the change aloud. If they cannot find them in the ticket, the note is not done. Silence is not agreement. Then leave the device alone.

This page is a planning guide. It is not a vendor manual, not an official standard, and not a permission to touch a network you do not administer. The pillar guide owns the wider design. This page owns one lab proof.

Tools for this guide

These tools run in the browser on this site. They do not log into your machines.

Packet Analysis Guide (Wireshark & tcpdump)

More in this cluster

The pillar for this page, and the next published pages filed with it.

Companion: Security: Log Analysis for Security.