diff --git a/files/interfaces-troisdorf6 b/files/interfaces-troisdorf6
index a423081..9b12f50 100644
--- a/files/interfaces-troisdorf6
+++ b/files/interfaces-troisdorf6
@@ -20,11 +20,19 @@ iface eth0 inet static
         netmask 255.255.255.192
         gateway 46.4.138.129
         dns-nameserver 213.133.100.100 213.133.99.99 213.133.98.98
+        post-up iptables -P OUTPUT ACCEPT
+        post-up iptables -A OUTPUT -o eth0 -d 10.0.0.0/8 -j DROP
+        post-up iptables -A OUTPUT -o eth0 -d 172.16.0.0/12 -j DROP
+        post-up iptables -A OUTPUT -o eth0 -d 169.254.0.0/16 -j DROP
+        post-up iptables -A OUTPUT -o eth0 -d 192.168.0.0/16 -j DROP
+        post-up iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
 
 iface eth0 inet6 static
         address 2a01:4f8:11d:600::189
         netmask 59
         gateway 2a01:4f8:11d:600::1
+        post-up ip6tables -P OUTPUT ACCEPT
+        post-up ip6tables -A OUTPUT -o eth0 -d fc00::/7 -j DROP
 
 # GRE Tunnel zum Rheinland Backbone
 # - Die Konfigurationsdaten werden vom Rheinland Backbone vergeben und zugewiesen
@@ -35,11 +43,15 @@ iface gre-bb-a.ak.ber inet static
         address 100.64.2.159
         netmask 255.255.255.254
         pre-up ip tunnel add $IFACE mode gre local 46.4.138.189 remote 185.66.195.0 ttl 255
+        post-up iptables -t nat -A POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
+        post-up iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         post-up ip link set $IFACE mtu 1400
+        post-down iptables -t nat -D POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
         post-down ip tunnel del $IFACE
 
 iface gre-bb-a.ak.ber inet6 static
         address 2a03:2260:0:159::2/64
+        post-up ip6tables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         netmask 64
 
 # Berlin Router B
@@ -48,11 +60,15 @@ iface gre-bb-b.ak.ber inet static
         address 100.64.2.161
         netmask 255.255.255.254
         pre-up ip tunnel add $IFACE mode gre local 46.4.138.189 remote 185.66.195.1 ttl 255
+        post-up iptables -t nat -A POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
+        post-up iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         post-up ip link set $IFACE mtu 1400
+        post-down iptables -t nat -D POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
         post-down ip tunnel del $IFACE
 
 iface gre-bb-b.ak.ber inet6 static
         address 2a03:2260:0:15a::2/64
+        post-up ip6tables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         netmask 64
 
 
@@ -62,12 +78,16 @@ iface gre-bb-a.ix.dus inet static
         address 100.64.2.163
         netmask 255.255.255.254
         pre-up ip tunnel add $IFACE mode gre local 46.4.138.189 remote 185.66.193.0 ttl 255
+        post-up iptables -t nat -A POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
+        post-up iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         post-up ip link set $IFACE mtu 1400
+        post-down iptables -t nat -D POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
         post-down ip tunnel del $IFACE
 
 iface gre-bb-a.ix.dus inet6 static
         address 2a03:2260:0:15b::2/64
         netmask 64
+        post-up ip6tables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
 
 
 # Duesseldorf Router B
@@ -76,10 +96,13 @@ iface gre-bb-b.ix.dus inet static
         address 100.64.2.165
         netmask 255.255.255.254
         pre-up ip tunnel add $IFACE mode gre local 46.4.138.189 remote 185.66.193.1 ttl 255
+        post-up iptables -t nat -A POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
+        post-up iptables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312
         post-up ip link set $IFACE mtu 1400
+        post-down iptables -t nat -D POSTROUTING -o $IFACE -j SNAT --to-source 185.66.193.106
         post-down ip tunnel del $IFACE
 
 iface gre-bb-b.ix.dus inet6 static
         address 2a03:2260:0:15c::2/64
         netmask 64
-
+        post-up ip6tables -t mangle -A POSTROUTING -p tcp --tcp-flags SYN,RST SYN -o $IFACE -j TCPMSS --set-mss 1312