Use: which lsmod
and after: which egrep
And use lsmod and egrep commands with full path’s that’s returned from which command
Sure!
root@k9sports:/# which lsmod
/usr/sbin/lsmod
root@k9sports:/# which egrep
/usr/bin/egrep
root@k9sports:/# /usr/sbin/lsmod | /usr/bin/egrep ‘net|filter|table|nft|ipt|bpf’
nft: no command specified
Command ‘table’ not found, but can be installed with:
snap install table
Command ‘filter’ not found, but can be installed with:
apt install filter
Command ‘bpf’’ not found, did you mean:
command ‘bpfc’ from deb netsniff-ng (0.6.5-1build1)
Try: apt install
Command ‘ipt’ not found, did you mean:
command ‘ipa’ from deb freeipa-client (4.8.6-1ubuntu2)
command ‘ppt’ from deb bsdgames (2.17-28build1)
command ‘iyt’ from deb python3-yt (3.5.1-3build1)
command ‘pt’ from deb tcllib (1.20+dfsg-1)
command ‘opt’ from deb llvm (1:10.0-50~exp1)
command ‘gpt’ from deb gpt (1.1-5build1)
command ‘apt’ from deb apt (2.0.9)
command ‘ipe’ from deb ipe (7.2.13-2build1)
command ‘ip’ from deb iproute2 (5.5.0-1ubuntu1)
command ‘idt’ from deb ncl-ncarg (6.6.2-1build4)
command ‘dpt’ from deb pkg-perl-tools (0.59)
command ‘iptc’ from deb libiptcdata-bin (1.0.5-2.1ubuntu4)
command ‘iat’ from deb iat (0.1.3-7build1)
command ‘ips’ from deb ips (4.0-1build3)
command ‘ipbt’ from deb its-playback-time (0.2017-08-30.3c40fd3-1)
Try: apt install
Exec only /usr/sbin/lsmod
Wrap commands in backticks (`) so they won’t get messed with by the formatter in Discourse (which converts some quotes to smart quotes, among other things).
And, OP, I strongly recommend you don’t run commands that someone suggest on a forum that you don’t understand. This command is harmless (if run correctly), but if you’re copy-pasting anything anybody tells you, you’re taking a big risk. We would remove anything that we saw that looked dangerous, but we aren’t watching 24/7, and we might miss something dangerous.
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The forum has converted the quotes in this command to something not recognized by your shell as a quote, as @rony did not wrap it in backticks.
They really meant this: lsmod | egrep 'net|filter|table|nft|ipt|bpf'
Which is looking for kernel modules that provide some kind of network filtering or policy routing.
I doubt it will provide any useful clues. But, it’s not harmful, anyway.
Do you get any output at all when listing iptables rules?
sudo iptables --list
Hi. I check dmesg output from author. What is it?
systemd[1]: Starting nftables…
This server is nftables enabled if this start command ended correctly.
What is output from: nft list tables
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Or nft list ruleset
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YES! YES! YES! nft was the culprit! I purged it completely from the server and now it works fine. I have no idea what package installed this on the server.
A huge thank you to rony and all the other people who helped work this through with me. And for all the patience trying to find what the issue was.
2 Likes
https://wiki.debian.org/nftables
Are you running any firewall now?
1 Like
This problem occurs if the upgrade of the debian-based distribution is done with a new installation and not via dist-upgrade.
The new version has a different utility by default, and there is already a problem. Debian had a default firewall change from iptables to nftables when switching from buster to bullseye I guess, it was also changed there during the new installation. But I still had iptables after the upgrade through dist-upgrade. I don’t know how it is in Ubuntu, in which version of it this transition occurred.
And it reminds @ID10T if you have any firewall activated at al 
. Watch out for that.
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