picosnitch 0.11.3

Protect your privacy, see which applications make network connections

picosnitch

• Receive notifications whenever a new program connects to the network, or when it's modified
• Monitors your bandwidth, breaking down traffic by executable, hash, parent, domain, port, or user over time
• Can optionally check hashes or executables using VirusTotal
• Executable hashes are cached based on device + inode for improved performance, and works with applications running inside containers
• Uses BPF for accurate, low overhead bandwidth monitoring and fanotify to watch executables for modification
• Since applications can call others to send/receive data for them, the parent executable and hash is also logged for each connection
• Focus is on monitoring and detection, and doing that well, this is not a firewall since that would increase complexity, impact performance, and can't be done as securely as sandboxing with something such as firejail, flatpak, or a virtual machine
• Note that applications could also be compromised via shared libraries, loading scripts, extensions, etc., and only the process executable itself is hashed, if this is a concern you may also want to see other host-based intrusion detection systems (HIDS) such as AIDE or something like debsums (with caveats) on top of checking for abnormal traffic
• Inspired by programs such as GlassWire, Little Snitch, and OpenSnitch

installation

PPA for Ubuntu and derivatives

• sudo add-apt-repository ppa:elesiuta/picosnitch
• sudo apt update
• sudo apt install picosnitch
• extra dependencies for dash (optional): dash, pandas, and plotly

AUR for Arch and derivatives

• install picosnitch manually or using your preferred AUR helper

PyPI for any Linux distribution with Python >= 3.8

• install the BPF Compiler Collection python package for your distribution
  • it should be called python-bcc or python-bpfcc
• install picosnitch using pip
  • pip3 install "picosnitch[full]" --upgrade --user
• create a service file for systemd to run picosnitch (recommended)
  • picosnitch systemd
• optional dependencies (will install from PyPI with [full] if not already installed)
  • for dash: dash, pandas, and plotly
  • for notifications: dbus-python, python-dbus, or python3-dbus (name depends on your distro and should be installed from their repo)
  • for sql server: one of psycopg, pymysql, mariadb, or psycopg2 (latter two not included with [full])
  • for VirusTotal: requests

usage

• running picosnitch
  • enable/disable autostart on reboot with systemctl enable|disable picosnitch
  • start/stop/restart with systemctl start|stop|restart picosnitch
  • or if you don't use systemd picosnitch start|stop|restart
• web user interface for browsing past connections
  • start with picosnitch dash
  • visit http://localhost:5100
• terminal user interface for browsing past connections
  • start with picosnitch view
  • space/enter: filter on entry backspace: remove filter h/H: cycle through history t/T: cycle time range u/U: cycle byte units r: refresh view q: quit
• show usage with picosnitch help

configuration

• config is stored in ~/.config/picosnitch/config.json
  • restart picosnitch if it is currently running for any changes to take effect

{
  "Bandwidth monitor": true, # Log traffic per connection since last db write
  "DB retention (days)": 365, # How many days to keep connection logs in snitch.db
  "DB sql log": true, # Write connection logs to snitch.db (SQLite)
  "DB sql server": {}, # Write connection logs to a MariaDB, MySQL, or PostgreSQL server
  "DB text log": false, # Write connection logs to conn.log
  "DB write limit (seconds)": 10, # Minimum time between writing connection logs
  # increasing it decreases disk writes by grouping connections into larger time windows
  # reducing time precision, decreasing database size, and increasing hash latency
  "Desktop notifications": true, # Try connecting to dbus to show notifications
  "Every exe (not just conns)": false, # Check every running executable with picosnitch
  # these are treated as "connections" with a port of -1
  # this feature is experimental but should work fairly well, errors should be expected as
  # picosnitch is unable to open file descriptors for some extremely short-lived processes
  # if you just want logs (no hashes) to trace process hierarchy, see execsnoop or forkstat
  "Log addresses": true, # Log remote addresses for each connection
  "Log commands": true, # Log command line args for each executable
  "Log ignore": [], # List of hashes (str), domains (str), or ports (int)
  # will omit connections that match any of these from the connection log
  # domains will match any that start with the provided string, hashes or ports are exact
  # the process name, executable, and hash will still be recorded in record.json
  # use with caution since applications could still be compromised without affecting hash
  # e.g. via shared libraries, loading scripts, extensions, etc.
  "Set RLIMIT_NOFILE": null, # Set the maximum number of open file descriptors (int)
  # it is used for caching process executables and hashes (typical system default is 1024)
  # this is good enough for most people since caching is based on executable device + inode
  # fanotify is used to detect if a cached executable is modified to trigger a hash update
  "VT API key": "", # API key for VirusTotal, leave blank to disable (str)
  "VT file upload": false, # Upload file if hash not found, only hashes are used by default
  "VT request limit (seconds)": 15 # Number of seconds between requests (free tier quota)
}

logging

• a log of seen executables is stored in ~/.config/picosnitch/exe.log
  • this is a history of your notifications
• a record of seen executables is stored in ~/.config/picosnitch/record.json
  • this is used for determining whether to create a notification
  • it contains known process name(s) by executable, executable(s) by process name, and sha256 hash(es) with VirusTotal results by executable
• enable DB sql log (default) to write the full connection log to ~/.config/picosnitch/snitch.db
  • this is used for picosnitch dash, picosnitch view, or something like DB Browser
  • note, connection times are based on when the group is processed, so they are accurate to within DB write limit (seconds) at best, and could be delayed if the previous group is slow to hash
  • notifications are handled by a separate subprocess, so they are not subject to the same delays as the connection log
• use DB sql server to write the full connection log to a MariaDB, MySQL, or PostgreSQL server
  • this is independent of DB sql log and is used for providing an off-system copy to prevent tampering (use GRANT to assign privileges)
  • to configure, add the key client to DB sql server with value mariadb, psycopg, psycopg2, or pymysql, you can also optionally set table_name
  • assign remaining connection parameters for mariadb, psycopg, or pymysql to DB sql server as key/value pairs
• enable DB text log to write the full connection log to ~/.config/picosnitch/conn.log
  • this may be useful for watching with another program
  • it contains the following fields, separated by commas (commas, newlines, and null characters are removed from values)
  • executable,name,cmdline,sha256,time,domain,ip,port,uid,parent_exe,parent_name,parent_cmdline,parent_sha256,conns,sent,received
• the error log is stored in ~/.config/picosnitch/error.log
  • errors will also trigger a notification and are usually caused by far too many or extremely short-lived processes/connections, or suspending your system while a new executable is being hashed
  • while it is very unlikely for processes/connections to be missed (unless Every exe (not just conns) is enabled), picosnitch was designed such that it should still detect this and log an error giving you some indication of what happened
  • for most people in most cases, this should raise suspicion that a program may be misbehaving

building from source

• install dependencies listed under installation
• install python-setuptools
• install picosnitch with python setup.py install --user
• see other options with python setup.py [build|install] --help
• you can also run the script picosnitch.py directly