netfilter project logo

The "ulogd" project

What is ulogd?

ulogd is a userspace logging daemon for netfilter/iptables related logging. This includes per-packet logging of security violations, per-packet logging for accounting, per-flow logging and flexible user-defined accounting.

ulogd-1.x has been around since 2000. Since 2012, 1.x series have entered end-of-life. All production systems should migrate to the stable series ulogd-2.x as soon as possible as we do not plan to make more 1.x releases.


ulogd-2.x requires several libraries:

  • libnfnetlink that provides basic communication infrastructure via Netlink.
  • libmnl that provides basic communication infrastructure via Netlink, this library will supersede libnfnetlink. Still, we require both libraries as we are still in transition to entirely replace libnfnetlink by libmnl.
  • libnetfilter_log for stateless packet-based logging via nfnetlink_queue.
  • libnetfilter_conntrack for stateful flow-based via nf_conntrack_netlink.
  • libnetfilter_acct for flexible traffic accounting via nfnetlink_acct and iptables nfacct match (it requires Linux kernel >= 3.3.x).

This requires a Linux kernel >= 2.6.14, but Linux kernel >= 2.6.18 is strongly recommended. Note that if you need SQL database output suport, you will need the header files of the respective libraries.

Legacy ulogd-1.x requires nothing netfilter-related.

Main Features

  • Packet and flow-based traffic accounting
  • Flexible user-defined traffic accounting via nfacct infrastructure
  • SQL database back-end support: SQLite3, MySQL and PostgreSQL
  • Text-based output formats: CSV, XML, Netfilter's LOG, Netfilter's conntrack


The current stable version of ulogd-2.x can be accessed at

The legacy stable version of ulogd-1.x can be accessed at This version has entered end-of-life. Any development effort has to be targeted to ulogd-2.x.


ulogd is currently maintained by Eric Leblond.


ulogd was almost entirely written by Harald Welte, with contributions from fellow hackers such as Pablo Neira Ayuso, Eric Leblond and Pierre Chifflier.

Copyright © 1999-2024 The Netfilter webmasters . Contact webmaster