sshguard(8) SSHGuard Manual sshguard(8)
NAME
sshguard - block brute-force attacks by aggregating system logs
SYNOPSIS
sshguard [-hv] [-a threshold] [-b threshold:blacklist_file] [-i pid-
file] [-p blocktime] [-s detection_time] [-w address | whitelist_file]
[file ...]
DESCRIPTION
sshguard protects hosts from brute-force attacks against SSH and other
services. It aggregates system logs and blocks repeat offenders using
one of several firewall backends.
sshguard can monitor log files. Log messages are parsed line-by-line
for recognized patterns. An attack is detected when several patterns
are matched in a set time interval. Attackers are blocked temporarily
but can also be semi-permanently banned using the blacklist option.
OPTIONS
-a threshold (default 30)
Block attackers when their cumulative attack score exceeds
threshold. Most attacks have a score of 10.
-b threshold:blacklist_file
Blacklist an attacker when its score exceeds threshold. Black-
listed addresses are loaded from and added to blacklist-file.
-i pidfile
Write the PID of sshguard to pidfile.
-p blocktime (default 120)
Block attackers for initially blocktime seconds after exceeding
threshold. Subsequent blocks increase by a factor of 1.5.
sshguard unblocks attacks at random intervals, so actual block
times will be longer.
-s detection_time (default 1800)
Remember potential attackers for up to detection_time seconds
before resetting their score.
[-w address | whitelist_file]
Whitelist a single address, hostname, or address block given as
address. This option can be given multiple times. Alternatively,
provide an absolute path to a whitelist_file containing
addresses to whitelist. See WHITELISTING.
-h Print usage information and exit.
-v Print version information and exit.
ENVIRONMENT
SSHGUARD_DEBUG
Set to enable verbose output from sshg-blocker.
FILES
%PREFIX%/etc/sshguard.conf
See sample configuration file.
WHITELISTING
Whitelisted addresses are never blocked. Addresses can be specified on
the command line or be stored in a file.
On the command line, give the -w option one or more times with an IP
address, CIDR address block, or hostname as an argument. Hostnames are
resolved once at startup. If a hostname resolves to multiple addresses,
all of them are whitelisted. For example:
sshguard -w 192.168.1.10 -w 192.168.0.0/24 -w friend.example.com
-w 2001:0db8:85a3:0000:0000:8a2e:0370:7334
-w 2002:836b:4179::836b:0000/126
If the argument to -w begins with a forward slash ('/') or dot ('.'),
the argument is treated as the path to a whitelist file.
The whitelist file contains comments (lines beginning with '#'),
addresses, address blocks, or hostnames, one per line.
SEE ALSO
sshguard-setup(7)
2.4 May 23, 2019 sshguard(8)
sshguard 2.4.0 - Generated Fri Jun 14 09:42:31 CDT 2019