$OpenBSD: pflog.4,v 1.10 2007/05/31 19:19:51 jmc Exp $
Copyright (c) 2001 Tobias Weingartner
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.Dd June 29, 2023 .Dt NPFLOG 4 .Os .Sh NAME .Nm npflog .Nd packet filter logging interface .Sh SYNOPSIS .Cd "pseudo-device npflog" .Sh DESCRIPTION The .Nm interface is a pseudo-device which makes visible all packets logged by the .Xr npf 7 packet filter. Logged packets can be monitored in real time by invoking .Xr tcpdump 8 on the .Nm interface, or stored to disk using .Xr npfd 8 .
p The npflog0 interface is created automatically at boot if .Xr npf 7 is enabled; further instances can be created using .Xr ifconfig 8 .
p Each packet retrieved on this interface has a header associated that presently matches the format used by .Xr pf 4 . This header documents the address family, interface name, rule number, reason, action, and direction of the packet that was logged. This structure looks like: d -literal -offset indent struct npfloghdr { uint8_t length; sa_family_t af; uint8_t action; uint8_t reason; char ifname[IFNAMSIZ]; char ruleset[NPFLOG_RULESET_NAME_SIZE]; uint32_t rulenr; uint32_t subrulenr; uint32_t uid; uint32_t pid; uint32_t rule_uid; uint32_t rule_pid; uint8_t dir; uint8_t pad[3]; }; .Ed .Sh EXAMPLES Monitor all packets logged on the default interface: d -literal -offset indent # tcpdump -n -e -tttt -i npflog0 .Ed .Sh SEE ALSO .Xr inet 4 , .Xr inet6 4 , .Xr netintro 4 , .Xr npf 7 , .Xr ifconfig 8 , .Xr npfd 8 , .Xr tcpdump 8 .Sh HISTORY The .Nm device first appeared in .Nx 6.0 .
Indexes created Sat Sep 20 22:09:52 GMT 2025