new file mode 100755
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+#!/usr/sin/nft -f
+
+# This example file shows how to use ct helpers in the nftables framework.
+# Note that nftables includes interesting improvements compared to how this
+# was done with iptables, such as loading multiple helpers with a single rule
+# This script is mean to be loaded with `nft -f <file>`
+# You require linux kernel >= 4.12 and nft >= 0.8
+# For up-to-date information please visit https://wiki.nftables.org
+
+# Using ct helpers is an important security feature when doing stateful
+# firewalling, since it mitigate certain networking attacks.
+# More info at: https://home.regit.org/netfilter-en/secure-use-of-helpers/
+
+
+flush ruleset
+table inet filter {
+ # declare helpers of this table
+ ct helper ftp-standard {
+ type "ftp" protocol tcp;
+ l3proto inet
+ }
+ ct helper sip-5060 {
+ type "sip" protocol udp;
+ l3proto inet
+ }
+ ct helper tftp-69 {
+ type "tftp" protocol udp
+ l3proto inet
+ }
+
+ chain input {
+ type filter hook input priority 0; policy drop;
+ ct state established,related accept
+
+ # assign a single helper in a single rule
+ tcp dport 21 ct helper set "ftp-standard"
+
+ # assign multiple helpers in a single rule
+ ct helper set udp dport map {
+ 69 : "tftp-69", \
+ 5060 : "sip-5060" }
+ }
+}
Include some examples in the nftables tarball on using the ct helper infraestructure, inspired from wiki.nftables.org. Signed-off-by: Arturo Borrero Gonzalez <arturo@netfilter.org> --- files/examples/ct_helpers.nft | 43 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100755 files/examples/ct_helpers.nft -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html