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pflog(4) [bsd man page]

PFLOG(4)						   BSD Kernel Interfaces Manual 						  PFLOG(4)

NAME
pflog -- packet filter logging interface SYNOPSIS
device pflog DESCRIPTION
The pflog interface is a pseudo-device which makes visible all packets logged by the packet filter, pf(4). Logged packets can easily be mon- itored in real time by invoking tcpdump(1) on the pflog interface, or stored to disk using pflogd(8). The pflog0 interface is created automatically at boot if both pf(4) and pflogd(8) are enabled; further instances can be created using ifconfig(8). Each packet retrieved on this interface has a header associated with it of length PFLOG_HDRLEN. This header documents the address family, interface name, rule number, reason, action, and direction of the packet that was logged. This structure, defined in <net/if_pflog.h> looks like struct pfloghdr { u_int8_t length; sa_family_t af; u_int8_t action; u_int8_t reason; char ifname[IFNAMSIZ]; char ruleset[PF_RULESET_NAME_SIZE]; u_int32_t rulenr; u_int32_t subrulenr; uid_t uid; pid_t pid; uid_t rule_uid; pid_t rule_pid; u_int8_t dir; u_int8_t pad[3]; }; EXAMPLES
Create a pflog interface and monitor all packets logged on it: # ifconfig pflog1 up # tcpdump -n -e -ttt -i pflog1 SEE ALSO
tcpdump(1) inet(4), inet6(4), netintro(4), pf(4), ifconfig(8), pflogd(8) HISTORY
The pflog device first appeared in OpenBSD 3.0. BSD
December 10, 2001 BSD

Check Out this Related Man Page

PFSYNC(4)						   BSD Kernel Interfaces Manual 						 PFSYNC(4)

NAME
pfsync -- packet filter state table logging interface SYNOPSIS
device pfsync DESCRIPTION
The pfsync interface is a pseudo-device which exposes certain changes to the state table used by pf(4). If configured with a physical syn- chronisation interface, pfsync will send state changes out on that interface using IP multicast, and insert state changes received on that interface from other systems into the state table. By default, all local changes to the state table are exposed via pfsync. However, state changes from packets received by pfsync over the network are not rebroadcast. States created by a rule marked with the no-sync keyword are omitted from the pfsync interface (see pf.conf(5) for details). The pfsync interface will attempt to collapse multiple updates of the same state into one message where possible. The maximum number of times this can be done before the update is sent out is controlled by the maxupd parameter to ifconfig (see ifconfig(8) and the example below for more details). Each packet retrieved on this interface has a header associated with it of length PFSYNC_HDRLEN. The header indicates the version of the protocol, address family, action taken on the following states, and the number of state table entries attached in this packet. This struc- ture is defined in <net/if_pfsync.h> as: struct pfsync_header { u_int8_t version; u_int8_t af; u_int8_t action; u_int8_t count; }; NETWORK SYNCHRONISATION
States can be synchronised between two or more firewalls using this interface, by specifying a synchronisation interface using ifconfig(8). For example, the following command sets fxp0 as the synchronisation interface: # ifconfig pfsync0 syncdev fxp0 It is important that the underlying synchronisation interface is up and has an IP address assigned. By default, state change messages are sent out on the synchronisation interface using IP multicast packets. The protocol is IP protocol 240, PFSYNC, and the multicast group used is 224.0.0.240. When a peer address is specified using the syncpeer keyword, the peer address is used as a destination for the pfsync traffic, and the traffic can then be protected using ipsec(4). In such a configuration, the syncdev should be set to the enc(4) interface, as this is where the traffic arrives when it is decapsulated, e.g.: # ifconfig pfsync0 syncpeer 10.0.0.2 syncdev enc0 It is important that the pfsync traffic be well secured as there is no authentication on the protocol and it would be trivial to spoof pack- ets which create states, bypassing the pf ruleset. Either run the pfsync protocol on a trusted network - ideally a network dedicated to pfsync messages such as a crossover cable between two firewalls, or specify a peer address and protect the traffic with ipsec(4). For pfsync to start its operation automatically at the system boot time, pfsync_enable and pfsync_syncdev variables should be used in rc.conf(5). It is not advisable to set up pfsync with common network interface configuration variables of rc.conf(5) because pfsync must start after its syncdev, which cannot be always ensured in the latter case. EXAMPLES
pfsync and carp(4) can be used together to provide automatic failover of a pair of firewalls configured in parallel. One firewall handles all traffic - if it dies or is shut down, the second firewall takes over automatically. Both firewalls in this example have three sis(4) interfaces. sis0 is the external interface, on the 10.0.0.0/24 subnet; sis1 is the internal interface, on the 192.168.0.0/24 subnet; and sis2 is the pfsync interface, using the 192.168.254.0/24 subnet. A crossover cable connects the two firewalls via their sis2 interfaces. On all three interfaces, firewall A uses the .254 address, while firewall B uses .253. The inter- faces are configured as follows (firewall A unless otherwise indicated): Interfaces configuration in /etc/rc.conf: network_interfaces="lo0 sis0 sis1 sis2" cloned_interfaces="carp0 carp1" ifconfig_sis0="10.0.0.254/24" ifconfig_sis1="192.168.0.254/24" ifconfig_sis2="192.168.254.254/24" ifconfig_carp0="vhid 1 pass foo 10.0.0.1/24" ifconfig_carp1="vhid 2 pass bar 192.168.0.1/24" pfsync_enable="YES" pfsync_syncdev="sis2" pf(4) must also be configured to allow pfsync and carp(4) traffic through. The following should be added to the top of /etc/pf.conf: pass quick on { sis2 } proto pfsync pass on { sis0 sis1 } proto carp If it is preferable that one firewall handle the traffic, the advskew on the backup firewall's carp(4) interfaces should be set to something higher than the primary's. For example, if firewall B is the backup, its carp1 configuration would look like this: ifconfig_carp1="vhid 2 pass bar advskew 100 192.168.0.1/24" The following must also be added to /etc/sysctl.conf: net.inet.carp.preempt=1 BUGS
Possibility to view state changes using tcpdump(1) has not been ported from OpenBSD yet. SEE ALSO
bpf(4), carp(4), ifconfig(8), inet(4), inet6(4), ipsec(4), netintro(4), pf(4), pf.conf(5), protocols(5), rc.conf(5) ifconfig(8), ifstated(8), tcpdump(8) HISTORY
The pfsync device first appeared in OpenBSD 3.3. The pfsync device was imported to FreeBSD 5.3. BSD
June 6, 2006 BSD

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