libnetfilter_conntrack is a userspace library providing a programming interface (API) to the in-kernel connection tracking state table. The library libnetfilter_conntrack has been previously known as libnfnetlink_conntrack and libctnetlink. This library is currently used by conntrack-tools among many other applications.

libnetfilter_log is a userspace library providing interface to packets that have been logged by the kernel packet filter. It is is part of a system that deprecates the old syslog/dmesg based packet logging. This library has been previously known as libnfnetlink_log.

libnetfilter_queue is a userspace library providing an API to packets that have been queued by the kernel packet filter. It is is part of a system that deprecates the old ip_queue / libipq mechanism.
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Build disabled for < 12.1 due to hitting make bug (Savannah bug #33125 (bnc #681108))

libnfnetlink is the low-level library for netfilter related kernel/userspace communication. It provides a generic messaging infrastructure for in-kernel netfilter subsystems (such as nfnetlink_log, nfnetlink_queue, nfnetlink_conntrack) and their respective users and/or management tools in userspace.

This library is not meant as a public API for application developers. It is only used by other netfilter.org projects, such as libnetfilter_log, libnetfilter_queue or libnetfilter_conntrack.

ulogd is a userspace logging daemon for netfilter/iptables related logging. This includes per-packet logging of security violations, per-packet logging for accounting purpose as well as per-flow logging.

Xtables is used to set up, maintain, and inspect the tables of IP
packet filter rules in the Linux kernel.

Xtables-addons is the successor to patch-o-matic(-ng). Likewise, it
contains extensions that were not, or are not yet, accepted in the
main kernel/iptables packages.

LibreSSL is an open-source implementation of the Secure Sockets Layer
(SSL) and Transport Layer Security (TLS) protocols. It derives from
OpenSSL, with the aim of refactoring the OpenSSL code so as to
provide a more secure implementation.

libdbi implements a database-independent abstraction layer in C, similar to the DBI/DBD layer in Perl. Writing one generic set of code, programmers can leverage the power of multiple databases and multiple simultaneous database connections by using this framework.

libdbi implements a database-independent abstraction layer in C, similar to the DBI/DBD layer in Perl. Drivers are distributed separately from the library itself.

sshfp generates DNS SSHFP records from SSH public keys. sshfp can
take public keys from a knownhosts file or from scanning the host's
sshd daemon. The ssh client can use these SSHFP records if you set
"VerifyHostKeyDNS yes" in the file /etc/ssh/ssh_config.

Brotli is a generic-purpose lossless compression algorithm that compresses data
using a combination of a modern variant of the LZ77 algorithm, Huffman coding
and 2nd order context modeling, with a compression ratio comparable to the best
currently available general-purpose compression methods. It is similar in speed
with deflate but offers more dense compression.

ngx_brotli is a set of two nginx modules:

ngx_brotli filter module - used to compress responses on-the-fly,
ngx_brotli static module - used to serve pre-compressed files.