traffic-shaping — Kernun firewall traffic shaping support


Kernun firewall supports traffic shaping. The PF/ALTQ package is used for this purpose, see pf(4), altq(4), pfctl(8), pf.conf(5). ALTQ sends outgoing network packets to queues. Each queue has its own bandwidth parameters that define how it sends packets to the network interface. Packets are assigned to queues by pf filter rules. Queues and filter rules are defined in pf configuration pf.conf(5).

All Kernun proxies support an alternative and more flexible way of assigning traffic to queues. Queue names can be set in ACLs. All communication that matches a particular ACL will use the queues specified in the ACL. This way, the queue selection process may utilize all conditions available for ACL matching, including time-based (slow download speed from some servers during working hours, remove limits in the night), or user-based limits (some users have priority). Queues for a session are configured separately for each communication direction, i.e., sending data to a client, server, antivirus, and antispam modules.


  • ALTQ works only for outgoing traffic. Received packets are not subject to traffic shaping.

  • ALTQ queue specifications in proxy ACLs require a kernel patch in order to work. Patching system sources and building a patched kernel is done as a part of the Kernun installation process.

  • Each UDP queue specification consists of a single queue name. TCP requires one or two queues. If two names are given, the second one is used only for prioritized packets, i.e., TCP acknowledgements without payload. Everything else is sent via the first queue.

  • In order to use ALTQ on a network interface, the network interface card driver must support it. For the list of supported drivers, see altq(4).

See Also

FreeBSD: altq(4), pf(4), pf.conf(5), pfctl(8)


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