Known problems

eBPF

cannot open kprove_events: open /sys/kernel/debug/tracing/kprobe_events: permission denied

cannot write ... kprobe_events: file exists

error while loading "kprobe/(...)": invalid argument

General

KDE/Gnome/Xfce/... does not boot up

GUI

GUI crash/exception/does not show up:

• NameError: name 'unicode' is not defined
• ModuleNotFoundError: No module named 'grpc'
• Others...

GUI not working across reboots

The GUI doesn't change to dark style theme

no icons on the GUI

GUI size problems on 4k monitors

OpenSnitch icon doesn't show up on Gnome-Shell

daemon

Kernel panic on >= 5.6.16 || kernel hardening incompatibilities

opensnitchd/daemon does not start:

---

Cannot open kprove_events

If after enabling eBPF you see the following error:

cannot open kprobe_events: open /sys/kernel/debug/tracing/kprobe_events: permission denied

you'll need to allow opensnitch in selinux or set it to permissive:

$ sudo journalctl -ar | grep "opensnitch.*lockdown"
Aug 19 06:18:28 localhost-live audit[2443]: AVC avc:  denied  { confidentiality } for  pid=2443 comm=opensnitchd lockdown_reason=use of tracefs scontext=system_u:system_r:unconfined_service_t:s0 tcontext=system_u:system_r:unconfined_service_t:s0 tclass=lockdown permissive=0

$ echo "Aug 19 06:18:28 localhost-live audit[2443]: AVC avc:  denied  { confidentiality } for  pid=2443 comm=opensnitchd lockdown_reason=use of tracefs scontext=system_u:system_r:unconfined_service_t:s0 tcontext=system_u:system_r:unconfined_service_t:s0 tclass=lockdown permissive=0" > opensnitch_lockdown.txt

$ sudo su
# audit2allow -M opensnitchd < opensnitch_lockdown.txt
# semanage -i opensnitchd.pp

You can download this generic selinux policy from here: https://github.com/evilsocket/opensnitch/issues/475#issuecomment-901838324

Useful links:

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/security-enhanced_linux/sect-security-enhanced_linux-fixing_problems-allowing_access_audit2allow

https://danwalsh.livejournal.com/24750.html

https://learn.netdata.cloud/docs/agent/collectors/ebpf.plugin

kprobe_events file exists

This error indicates that the network hooks are already added, you'll need to delete them manually:

$ sudo su
# > /sys/kernel/debug/tracing/kprobe_events

Error while loading kprobes: invalid argument

eBPF Failed to load /etc/opensnitchd/opensnitch.o: error while loading "kprobe/tcp_v4_connect" (invalid argument):

This error may indicate that your kernel doesn't have ftrace support, which is needed for eBPF to work.

CONFIG_FTRACE should be y and the directory /sys/kernel/debug/tracing/ must exist.

$ grep CONFIG_FTRACE /boot/config-$(uname-r)
CONFIG_FTRACE=y

If the output is # CONFIG_FTRACE is not set, your kernel is not compiled with ftrace support.

Read more: #475

Desktop Environment does not boot up

If after installing OpenSnitch, or after changing the Default Action to deny, the Desktop Environment does not show up (after restart), try:

1. setting the DefaultAction back to allow
2. adding a rule to allow system apps.

In both cases the idea is to allow certain programs needed by KDE, Gnome, etc: dirmngr, xbrlapi, host, kdeinit5. more info #402:

Save it to /etc/opensnitchd/rules/000-allow-system-cmds.json

{
  "created": "2021-04-26T09:58:03.704090244+02:00",
  "updated": "2021-04-26T09:58:03.704216578+02:00",
  "name": "000-allow-system-cmds",
  "enabled": true,
  "precedence": true,
  "action": "allow",
  "duration": "always",
  "operator": {
    "type": "regexp",
    "operand": "process.path",
    "sensitive": false,
    "data": "^(/usr/bin/host|/usr/bin/xbrlapi|/usr/bin/dirmngr)",
    "list": []
  }
}

You can also allow all traffic to localhost (save it to /etc/opensnitchd/rules/000-allow-localhost.json):

{
  "created": "2021-04-26T09:58:03.704090244+02:00",
  "updated": "2021-04-26T09:58:03.704216578+02:00",
  "name": "000-allow-localhost",
  "enabled": true,
  "precedence": true,
  "action": "allow",
  "duration": "always",
  "operator": {
    "type": "network",
    "operand": "dest.network",
    "sensitive": false,
    "data": "127.0.0.0/8",
    "list": []
  }
}

---

GUI crash/exception or does not show up

If you have installed it by double clicking on the pkgs, using a graphical installer, try to install it from command line:

$ sudo dpkg -i *opensnitch*deb; sudo apt -f install

See issue #25, issue #16 and issue #32 for additional information.

---

You have to install unicode_slugify and grpcio-tools, usually not available in many distros. You can install them using pip:

pip3 install unicode_slugify
pip3 install grpcio-tools

---

Check that you don't have a previous installation of opensnitch GUI in /usr/lib/python3*/*/opensnitch/ or /usr/local/lib/python3*/*/opensnitch/

If you have a previous installation remove it, and install the GUI again (you may have an installation of the original repo).

If it doesn't work, report it describing the steps to reproduce it, and the exception or log. For example:

Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/opensnitch/dialogs/prompt.py", line 362, in _on_apply_clicked
    self._rule.name = slugify("%s %s %s" % (self._rule.action, self._rule.operator.type, self._rule.operator.data))
  File "/usr/lib/python3.8/site-packages/slugify.py", line 24, in slugify
    unicode(
NameError: name 'unicode' is not defined

--

For ArchLinux/Manjaro users this worked:

installed was from AUR python-unicode-slugify-git r43.b696c37-1

removed it and installed python-unicode-slugify 0.1.3-1.

---

Opensnicth GUI not working across reboots

If after installing OpenSnitch and reboot, the GUI does not show up upon login to your Desktop Environment, be sure that the following path exist in your $HOME:

ls ~/.config/autostart/opensnitch_ui.desktop

If it doesn't exist, create it:

$ mkdir -p ~/.config/autostart/
$ ln -s /usr/share/applications/opensnitch_ui.desktop ~/.config/autostart/

If you have installed the GUI from the repositories of a distribution, tell the maintainer of the package to create that symbolic link after installation.

see issue #434 for more information.

---

The GUI does not change to dark style theme

It's usually a problem of the Desktop Environment. You can try to configure the theme by using qt5ct, or executing the following commands:

sudo apt-get install -y qt5-style-plugins
sudo cat << EOF | sudo tee  /etc/environment
QT_QPA_PLATFORMTHEME=gtk2
EOF

More info: #303

---

No icons on the GUI

Be sure that you have properly set the icon theme of your Window Manager. More information

---

GUI size problems on 4k monitors

Some users have reported issues displaying the GUI on 4k monitors. See #43 for more information.

Setting these variables may help:

export QT_AUTO_SCREEN_SCALE_FACTOR=0
export QT_SCREEN_SCALE_FACTORS=1 (or 1.25, 1.5, 2, ...)

In case of multiple displays: export "QT_SCREEN_SCALE_FACTORS=1;1"

---

OpenSnitch icon does not show up on Gnome-Shell

On Gnome-Shell >= 3.16, systray icons have been removed. You have to install the extension gnome-shell-extension-appindicator to get them back.

1. Download latest version - https://github.com/ubuntu/gnome-shell-extension-appindicator/releases
2. Install it with your regular user: gnome-extensions install gnome-shell-extension-appindicator-v33.zip

See this comment/issue for more information: #44

---

opensnitchd does not start

For all these options,

• Error while creating queue #0: Error binding to queue: operation not permitted.
• Error while enabling probe descriptor for opensnitch_exec_probe: write /sys/kernel/debug/tracing/kprobe_events: no such file or directory (the kernel does not have support for CONFIG_FTRACE, or it's not loaded)
• Error while creating queue #0: Error binding to queue: operation not permitted.
• iptables: Protocol wrong type for socket (modules nf_defrag_ipv4, nf_conntrack_ipv4 not loaded)
• Error opening Queue handle: protocol not supported (nfnetlink module not loaded)
• Could not open socket to kernel: Address family not supported by protocol (IPv6)
• Error while creating queue #0: Error unbinding existing q handler from AF_INET protocol see #323 and #204. (probably ip_queue loaded. Unload it and try again)

be sure that you have NFQUEUE support in the kernel (=y or =m):

$ grep -E "(NFT|NETLINK|NFQUEUE) /boot/config-$(uname -r)"
CONFIG_NFT_QUEUE=y
CONFIG_NETFILTER_NETLINK_QUEUE=y
CONFIG_NETFILTER_XT_TARGET_NFQUEUE=y

and that the needed modules are loaded:

$ lsmod | grep -i nfqueue
xt_NFQUEUE             16384  4
x_tables               53248  20 xt_conntrack,nft_compat,xt_LOG,xt_multiport,xt_tcpudp,xt_addrtype,xt_CHECKSUM,xt_recent,xt_nat,ip6t_rt,xt_set,ip6_tables,ipt_REJECT,ip_tables,xt_limit,xt_hl,xt_MASQUERADE,ip6t_REJECT,xt_NFQUEUE,xt_mark

The following modules are also needed:

nf_defrag_ipv4.ko, nf_conntrack_ipv4.ko, nfnetlink.ko

---

Kernel panics

Some users have reported kernel panics with kernel 5.6.16 (#297) and other kernels(#41). deathtrip found that the culprit in his/her case was a configuration of the Arch's linux-hardened kernel command line option.

Removing the following options from the kernel booting parameters solved the issue:

slab_nomerge, slub_debug=FZP and page_alloc.shuffle=1

On Debian with kernel 5.7.0, remove slub_debug=FZP if you have it configured and try again.

Note: This was caused by a bug in the libnetfilter_queue library.