Fatal error: Failed to create nftables chains or rules

[Bob Bob]

Hi, Hi, I'm trying to use rtpengine in Kernel mode on Debian 12, but it didn't work.

What's being used:
Kamailio v-6.0.4
ngcp-rtpengine v-12.5

When executing systemctl start ngcp-rtpengine-daemon, the log shows:

ERR: [core] FAILED TO CREATE NFTABLES CHAINS OR RULES, KERNEL FORWARDING POSSIBLY WON'T WORK: error returned from netlink for add rule (No such file or directory)
ERR: [core] FAILED TO CREATE KERNEL TABLE 0 (No such file or directory), KERNEL FORWARDING DISABLED
INFO: [core] Startup complete, version 12.5.1.2+0~mr12.5.1.2
INFO: [http] Websocket listener thread running
INFO: [core] Version 12.5.1.2+0~mr12.5.1.2 shutting down
INFO: [crypto] Generating new DTLS certificate
...

The following are some information about the server:

uname -a:

Linux lenovo 6.1.0-41-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.1.158-1 (2025-11-09) x86_64 GNU/Linux

uname -r:

6.1.0-41-amd64

dpkg -l | grep rtp:

ii  ngcp-rtpengine                          12.5.1.2+0~mr12.5.1.2               all          NGCP RTP/media proxy - meta package
ii  ngcp-rtpengine-daemon                   12.5.1.2+0~mr12.5.1.2               amd64        proxy for RTP and media streams used in NGCP, userspace part
ii  ngcp-rtpengine-kernel-dkms              12.5.1.2+0~mr12.5.1.2               all          IPtables kernel module for the NGCP media proxy - DKMS
ii  ngcp-rtpengine-perftest                 12.5.1.2+0~mr12.5.1.2               amd64        helper tool to test rtpengine transcoding performance
ii  ngcp-rtpengine-perftest-data            12.5.1.2+0~mr12.5.1.2               all          helper tool to test rtpengine transcoding performance - data files
ii  ngcp-rtpengine-recording-daemon         12.5.1.2+0~mr12.5.1.2               amd64        recording daemon for RTP and media streams
ii  ngcp-rtpengine-utils                    12.5.1.2+0~mr12.5.1.2               all          scripts and Perl modules for NGCP rtpengine

dpkg -l | grep head:

ii  linux-headers-6.1.0-41-amd64            6.1.158-1                           amd64        Header files for Linux 6.1.0-41-amd64
ii  linux-headers-6.1.0-41-common           6.1.158-1                           all          Common header files for Linux 6.1.0-41

dpkg -l | grep nft:

ii  libnftables1:amd64                    1.0.6-2+deb12u2                amd64        Netfilter nftables high level userspace API library
ii  libnftnl11:amd64                      1.2.4-2                        amd64        Netfilter nftables userspace API library
ii  nftables                              1.0.6-2+deb12u2                amd64        Program to control packet filtering rules by Netfilter project

However, the execution succeeds on another server.

Did I miss something?

Thanks.

[Richard Fuchs]

On 05/12/2025 02.11, Bob Bob wrote:
> ERR: [core] FAILED TO CREATE NFTABLES CHAINS OR RULES, KERNEL
> FORWARDING POSSIBLY WON'T WORK: error returned from netlink for add
> rule (No such file or directory)
> ERR: [core] FAILED TO CREATE KERNEL TABLE 0 (No such file or
> directory), KERNEL FORWARDING DISABLED

That usually means the kernel module isn't available. Normally it would
get loaded automatically, but try manually with `sudo modprobe
xt_RTPENGINE` to see what happens.

If it isn't, check the output of `sudo dkms status` if it has been
compiled for your kernel version. You can force a rebuild with `sudo
dpkg-reconfigure ngcp-rtpengine-kernel-dkms`

Cheers