path: root/include/hash.h
diff options
authorPablo Neira Ayuso <>2016-08-26 18:00:00 +0200
committerPablo Neira Ayuso <>2016-08-29 20:30:29 +0200
commit345236211715ffb7cc28f6ff0b26acb90181e738 (patch)
treeaebfc9aeece1dda1bb1ffab52aa93a9b1114f928 /include/hash.h
parent13eeed6ea6f0a5d1353ee5ad14c4322695b4f59b (diff)
src: add hash expression
This is special expression that transforms an input expression into a 32-bit unsigned integer. This expression takes a modulus parameter to scale the result and the random seed so the hash result becomes harder to predict. You can use it to set the packet mark, eg. # nft add rule x y meta mark set jhash ip saddr . ip daddr mod 2 seed 0xdeadbeef You can combine this with maps too, eg. # nft add rule x y dnat to jhash ip saddr mod 2 seed 0xdeadbeef map { \ 0 :, \ 1 : \ } Currently, this expression implements the jenkins hash implementation available in the Linux kernel: But it should be possible to extend it to support any other hash function type. Signed-off-by: Pablo Neira Ayuso <>
Diffstat (limited to 'include/hash.h')
1 files changed, 7 insertions, 0 deletions
diff --git a/include/hash.h b/include/hash.h
new file mode 100644
index 00000000..bc8c86af
--- /dev/null
+++ b/include/hash.h
@@ -0,0 +1,7 @@
+extern struct expr *hash_expr_alloc(const struct location *loc,
+ uint32_t modulus, uint32_t seed);
+#endif /* NFTABLES_HASH_H */