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-rw-r--r--ppp/ip-up.ipv6to420
1 files changed, 18 insertions, 2 deletions
diff --git a/ppp/ip-up.ipv6to4 b/ppp/ip-up.ipv6to4
index da0ba48e..be45e488 100644
--- a/ppp/ip-up.ipv6to4
+++ b/ppp/ip-up.ipv6to4
@@ -9,7 +9,7 @@
# You will find more information in the IPv6-HowTo for Linux at
# http://www.bieringer.de/linux/IPv6/
#
-# Version 2002-11-02
+# Version 2002-11-12a
#
# Calling parameters:
# $1: interface name
@@ -27,6 +27,7 @@
# IPV6TO4INIT=yes|no: controls configuration
# IPV6TO4_IPV4ADDR=<IPv4 address>: special local address for 6to4 tunneling (only needed behind a NAT gateway)
# IPV6TO4_RELAY=<IPv4 address>: remote 6to4 relay router address (default: 192.88.99.1)
+# IPV6TO4_MTU=<MTU for IPv6>: controls IPv6 MTU for the 6to4 link (optional, default is MTU of interface - 20)
# IPV6TO4_ROUTING="<device>-<suffix>/<prefix length> ...": information to setup local subnetting
# Example: IPV6TO4_ROUTING="eth0-:f101::0/64 eth1-:f102::0/64"
#
@@ -119,8 +120,23 @@ if [ "$IPV6TO4INIT" = "yes" ]; then
# Cleanup all old data (needed, if "ip-down.ipv6to4" wasn't executed), delete all configured 6to4 address
ipv6_cleanup_6to4_tunnels tun6to4
+ # Get MTU of master device
+ ipv4mtu="`ipv6_exec_ip link show dev $DEVICE | grep -w "mtu" | awk '{ print $5 }'`"
+ if [ -n "$ipv4mtu" ]; then
+ # IPv6 tunnel MTU is IPv4 MTU minus 20 for IPv4 header
+ tunnelmtu=$[ $ipv4mtu - 20 ]
+ fi
+
+ if [ -n "$IPV6TO4_MTU" ]; then
+ if [ $IPV6TO4_MTU -gt $tunnelmtu ]; then
+ echo $"Warning: configured MTU '$IPV6TO4_MTU' for 6to4 exceeds maximum limit of '$tunnelmtu', ignored"
+ else
+ tunnelmtu=$IPV6TO4_MTU
+ fi
+ fi
+
# Setup new data
- ipv6_add_6to4_tunnel tun6to4 $ipv4addr || exit 1
+ ipv6_add_6to4_tunnel tun6to4 $ipv4addr "" $tunnelmtu || exit 1
# Add default route, if device matches
if [ "$IPV6_DEFAULTDEV" = "tun6to4" ]; then