Document OpenBSD "ifconfig link0" and Linux "ip tuntap" commands.

[oweals/tinc.git] / doc / tinc.texi

diff --git a/doc/tinc.texi b/doc/tinc.texi
index 8bf0a6f5d2ea978f924008ba522f2df67417a3c2..4aaf507c3974f868c63b8074bc123540f954bf65 100644 (file)
--- a/doc/tinc.texi
+++ b/doc/tinc.texi
@@ -794,12 +794,14 @@ tinc won't try to connect to other daemons at all,
 and will instead just listen for incoming connections.
 
 @cindex DecrementTTL
-@item DecrementTTL = <yes | no> (yes)
+@item DecrementTTL = <yes | no> (no)
 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
 before forwarding a received packet to the virtual network device or to another node,
 and will drop packets that have a TTL value of zero,
 in which case it will send an ICMP Time Exceeded packet back.
 
+Do not use this option if you use switch mode and want to use IPv6.
+
 @cindex Device
 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
 The virtual network device to use.
@@ -830,6 +832,14 @@ All packets are read from this interface.
 Packets received for the local node are written to the raw socket.
 However, at least on Linux, the operating system does not process IP packets destined for the local host.
 
+@cindex multicast
+@item multicast
+Open a multicast UDP socket and bind it to the address and port (separated by spaces) and optionally a TTL value specified using @var{Device}.
+Packets are read from and written to this multicast socket.
+This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
+Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
+Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
+
 @cindex UML
 @item uml (not compiled in by default)
 Create a UNIX socket with the filename specified by
@@ -2394,7 +2404,6 @@ For IPv4 addresses:
 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
 @end multitable
 
-
 For IPv6 addresses:
 
 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
@@ -2416,6 +2425,22 @@ For IPv6 addresses:
 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
 @end multitable
 
+On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
+
+@multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
+@item OpenBSD
+@tab @code{ifconfig} @var{interface} @code{link0}
+@end multitable
+
+On Linux, it is possible to create a persistent tun/tap interface which will
+continue to exist even if tinc quit, although this is normally not required.
+It can be useful to set up a tun/tap interface owned by a non-root user, so
+tinc can be started without needing any root privileges at all.
+
+@multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
+@item Linux
+@tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
+@end multitable
 
 @c ==================================================================
 @node    Routes