path: root/src/scanner.l
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 /src/scanner.l
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 'src/scanner.l')
1 files changed, 3 insertions, 0 deletions
diff --git a/src/scanner.l b/src/scanner.l
index cff375f3..8b5a383b 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -471,6 +471,9 @@ addrstring ({macaddr}|{ip4addr}|{ip6addr})
"inc" { return INC; }
"mod" { return MOD; }
+"jhash" { return JHASH; }
+"seed" { return SEED; }
"dup" { return DUP; }
"fwd" { return FWD; }