diff options
Diffstat (limited to 'sys/netinet/libalias/libalias.3')
| -rw-r--r-- | sys/netinet/libalias/libalias.3 | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/sys/netinet/libalias/libalias.3 b/sys/netinet/libalias/libalias.3 index b4d123682f0b..1b8ecc14059d 100644 --- a/sys/netinet/libalias/libalias.3 +++ b/sys/netinet/libalias/libalias.3 @@ -23,7 +23,7 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd May 31, 2021 +.Dd November 29, 2024 .Dt LIBALIAS 3 .Os .Sh NAME @@ -200,11 +200,11 @@ is closed. .It Dv PKT_ALIAS_UNREGISTERED_ONLY If this mode bit is set, traffic on the local network which does not originate from unregistered address spaces will be ignored. -Standard Class A, B and C unregistered addresses are: +The standard private IP address ranges are: .Pp -10.0.0.0 -> 10.255.255.255 (Class A subnet) -172.16.0.0 -> 172.31.255.255 (Class B subnets) -192.168.0.0 -> 192.168.255.255 (Class C subnets) +10.0.0.0 -> 10.255.255.255 (/8) +172.16.0.0 -> 172.31.255.255 (/16) +192.168.0.0 -> 192.168.255.255 (/24) .Pp This option is useful in the case that the packet aliasing host has both registered and unregistered subnets on different interfaces. @@ -270,6 +270,26 @@ See section in .Xr ipfw 8 for more details. +.It Dv PKT_ALIAS_UDP_EIM +When this bit is set, UDP uses endpoint-independent mapping (EIM), as per +RFC 4787 ("full cone" NAT of RFC 3489). +All packets from the same internal address:port are mapped to the same NAT +address:port, regardless of their destination address:port. +If filtering rules allow, and if +.Em PKT_ALIAS_DENY_INCOMING +is unset, any other external address:port can +also send to the internal address:port through its mapped NAT address:port. +This is more compatible with applications, and can reduce the need for port +forwarding, but less scalable as each NAT address:port can only be +concurrently used by at most one internal address:port. +.Pp +When this bit is unset, UDP packets use endpoint-dependent mapping (EDM) +("symmetric" NAT). +Each connection from a particular internal address:port to different +external addresses:ports is mapped to a random and unpredictable NAT +address:port. +Two appplications behind EDM NATs can only connect to each other +by port forwarding on the NAT, or tunnelling through an in-between server. .El .Ed .Pp |