grml-sniff: disable IPv6 to avoid neighbor solicitation/multicast traffic

With IPv6 enabled the devices leak IPv6 traffic because
of the way IPv6 works™:

| 16:24:20.074982 IP6 (hlim 1, next-header Options (0) payload length: 36) :: > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr [...] to_ex { }]
| 16:24:20.319025 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 24) :: > ff02::1:ffab:3f90: [icmp6 sum ok] ICMP6, neighbor solicitation, length 24, who has [...]
| 16:24:21.319027 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) [...] > ip6-allrouters: [icmp6 sum ok] ICMP6, router solicitation, length 16
| [...]
| 16:24:23.619025 IP6 (hlim 1, next-header Options (0) payload length: 36) [...] > ff02::16: HBH (rtalert: 0x0000) (padn) [icmp6 sum ok] ICMP6, multicast listener report v2, 1 group record(s) [gaddr ff02::1:ffab:3f90 to_ex { }]
| 16:24:25.330982 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) [...] > ip6-allrouters: [icmp6 sum ok] ICMP6, router solicitation, length 16
|           source link-address option (1), length 8 (1): [...]
|             0x0000:  001d 92ab 3f90
| 16:24:29.338972 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) [...] > ip6-allrouters: [icmp6 sum ok] ICMP6, router solicitation, length 16
|           source link-address option (1), length 8 (1): [...]
|             0x0000:  001d 92ab 3f90

So when starting the sniffing setup disable IPv6 and
when stopping the sniffing setup re-enable it again.

diff --git a/sbin/grml-sniff b/sbin/grml-sniff
index d854f5d..cbb8ec1 100755 (executable)
--- a/sbin/grml-sniff
+++ b/sbin/grml-sniff
@@ -45,6 +45,10 @@ case "$1" in
         check4root || exit 1
         einfo "Starting sniffing setup"
         eindent
         check4root || exit 1
         einfo "Starting sniffing setup"
         eindent

+
+            einfo "Disabling IPv6 to avoid neighbor solicitation/multicast traffic"
+            echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
+

             einfo "Creating bridge device"
             brctl addbr "$BRIDGE_NAME"
             eend $?
             einfo "Creating bridge device"
             brctl addbr "$BRIDGE_NAME"
             eend $?


@@ -98,6 +102,9 @@ case "$1" in
             ifconfig "$BRIDGE_NAME" down || /bin/true
             brctl delbr "$BRIDGE_NAME"
             eend $?
             ifconfig "$BRIDGE_NAME" down || /bin/true
             brctl delbr "$BRIDGE_NAME"
             eend $?

+
+            einfo "Re-enabling IPv6"
+            echo 0 > /proc/sys/net/ipv6/conf/all/disable_ipv6

         eoutdent
    ;;
 
         eoutdent
    ;;