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ifconfig.if(5) [netbsd man page]

IFCONFIG.IF(5)						      BSD File Formats Manual						    IFCONFIG.IF(5)

ifconfig.if -- interface-specific configuration files or variables DESCRIPTION
The ifconfig.if files or variables contain information regarding the configuration of each network interface. ifconfig.if is processed by /etc/rc.d/network at system boot time. For each interface (nnX) that is to be configured, there should be either an ifconfig_nnX variable in rc.conf(5), or an /etc/ifconfig.nnX file (such as the ifconfig_fxp0 variable or the /etc/ifconfig.fxp0 file for the fxp0 interface). Only characters allowed in sh(1) variables names should be used for nnX (ascii(7) uppercase and lowercase letters, digits, and underscore). The variable or file will get evaluated only if the interface exists on the system. Multiple lines can be placed in a variable or file, and will be evaluated sequentially. In the case of a variable, semicolons may be used instead of newlines, as described in rc.conf(5). <backslash><newline> sequences in files are ignored, so long logical lines may be made up of several shorter physical lines. Normally, a line will be evaluated as command line arguments to ifconfig(8). ``ifconfig nnX'' will be prepended on evaluation. Arguments with embedded shell metacharacters should be quoted in sh(1) style. If the line is equal to ``dhcp'', dhcpcd(8) will be started for the interface. However, it is instead recommended that dhcpcd is set to true in rc.conf(5) and any per interface configuration or restriction is done in dhcpcd.conf(5). If a line is empty, or starts with '#', the line will be ignored as comment. If a line starts with '!', the rest of line will get evaluated as shell script fragment. Shell variables declared in /etc/rc.d/network are accessible but may not be modified. The most useful variable is $int, as it will be bound to the interface being configured with the file. For example, the following illustrates static interface configuration: # IPv4, with an alias inet netmask media 100baseTX inet netmask alias # let us have IPv6 address on this interface inet6 2001:db8::1 prefixlen 64 alias # have subnet router anycast address too inet6 2001:db8:: prefixlen 64 alias anycast The following illustrates dynamic configuration setup with dhclient(8) and rtsol(8): up # autoconfigure IPv4 address !dhclient $int # autoconfigure IPv6 address. Be sure to set $ip6mode to autohost. !rtsol $int The following example sets a network name for a wireless interface (using quotes to protect special characters in the name), and starts dhcpcd(8): ssid 'my network' dhcp The following example is for dynamically-created pseudo interfaces like gif(4). Earlier versions of /etc/rc.d/network required an explicit 'create' command for such interfaces, but creation is now handled automatically. up # configure IPv6 default route toward the interface !route add -inet6 default ::1 !route change -inet6 default -ifp $int FILES
/etc/rc.d/network SEE ALSO
rc.conf(5), ifconfig(8) BSD
April 7, 2011 BSD

Check Out this Related Man Page

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

pfsync -- packet filter state table logging interface SYNOPSIS
pseudo-device pfsync DESCRIPTION
The pfsync interface is a pseudo-device which exposes certain changes to the state table used by pf(4). State changes can be viewed by invoking tcpdump(8) on the pfsync interface. If configured with a physical synchronisation interface, pfsync will also 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 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 When a peer address is specified using the syncpeer keyword, the peer address is used as a destination for the pfsync traffic. 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) (it is not supported at the moment on NetBSD due to the lack of any encapsulation pseudo-device). There is a one-to-one correspondence between packets seen by bpf(4) on the pfsync interface, and packets sent out on the synchronisation interface, i.e. a packet with 4 state deletion messages on pfsync means that the same 4 deletions were sent out on the synchronisation inter- face. However, the actual packet contents may differ as the messages sent over the network are "compressed" where possible, containing only the necessary information. 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 subnet; sis1 is the internal interface, on the subnet; and sis2 is the pfsync interface, using the 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): /etc/ifconfig.sis0: inet NONE /etc/ifconfig.sis1: inet NONE /etc/ifconfig.sis2: inet NONE /etc/ifconfig.carp0: inet vhid 1 pass foo /etc/ifconfig.carp1: inet vhid 2 pass bar /etc/ifconfig.pfsync0: up 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 /etc/ifconfig.carp1 would look like this: inet vhid 2 pass bar advskew 100 The following must also be added to /etc/sysctl.conf: net.inet.carp.preempt=1 SEE ALSO
bpf(4), carp(4), inet(4), inet6(4), ipsec(4), netintro(4), pf(4), ifconfig.if(5), pf.conf(5), protocols(5), ifconfig(8), tcpdump(8) HISTORY
The pfsync device first appeared in OpenBSD 3.3. CAVEATS
pfsync is not available when using pf(4) as a kernel module. BSD
April 12, 2010 BSD
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