tallow¶

Reduce log clutter due to ssh login attempts.

SYNOPSIS¶

/usr/sbin/tallow

DESCRIPTION¶

tallow is a daemon that watches the systemd journal for messages from the sshd service. It parses the messages and looks for attempted random logins such as failed logins to the root account and failed logins to invalid user accounts, and various other obviously malicious login attempts that try things as forcing old protocols, or weak key systems.

If such logins were detected, the offending IP address is stored in a list. Items from this list are regularly purged, but if the amount of times that a specific IP address is seen exceeds a threshold, an ipset(1) entry is inserted in the tallow or tallow6 ipset, and further packets from that ip address will be blocked by an iptables(1) or ip6tables(1) rule that tallow creates at startup. Additionally, certain types of login failure will trigger a short term ban of further packets from the offending IP address immediately.

The system administrator needs to assure that the tallow and tallow6 ipsets are left alone and that the inserted iptables rules are properly matching on packets.

Care should be taken to assure that legitimate users are not blocked inadvertently. You may wish to list any valid IP address with the whitelist option in tallow.conf(5). Multiple addresses can be whitelisted.

OPTIONS¶

The tallow daemon itself has no runtime configuration. All configuration is done through the tallow.conf(5) config file.

SIGNALS¶

The USR1 signal causes tallow to print out it’s internal tracking table of IP addresses. This requires that tallow is compiled with the -DDEBUG=1 symbol passed to the compiler.

BUGS¶

tallow is NOT A SECURITY SOLUTION, nor does it protect against random password logins. A attacker may still be able to logon to your systems if you allow password logins.