# Math operations

Revision as of 13:05, 5 January 2017 by Arturo (talk | contribs) (→Number generator: add one more example)

nftables includes some interesting math operations generators which can be used to perform advanced operations like Load balancing.

# Number generator

The number generator statement has these options:

- type: inc/random.
- modulus: maximun number
- offset: from what value you want to start from

Some examples, distributing marks to packets:

```
table ip t {
chain c {
mark set numgen inc mod 4 offset 3
mark set numgen random mod 50 offset 20
mark set numgen inc mod 100
}
}
```

The statement **numgen inc mod 2 offset 100** will generate numbers in a series like 100, 101, 100, 101...

# Hashing

nftables support hashing of any arbitrary key combination:

```
table ip t {
chain c {
mark set jhash ip saddr mod 2
mark set jhash ip saddr . tcp dport mod 2
mark set jhash ip saddr . tcp dport . iiftype mod 2
}
}
```