/etc/security/shield.conf is the configuration file for PAM module pam_shield, which locks out remote attackers trying password guessing.


debug [on|off]

Log (or do not log) debugging information via syslog(3). block [all-users|unknown-users]

Block all users, or only unknown users. Whether users are "known" is determined from getpwnam(3) allow_missing_dns [yes|no]

If no, reject any connection that comes from a numerical IP address with no DNS name (as returned by pam_get_item(3) with item_type set to PAM_RHOST). allow_missing_reverse [yes|no]

If no, reject any connection that comes from a host with no reverse DNS entry. allow hostname

Host or network to whitelist. These hosts are passed through with no checks or logging. Multiple allow lines are permitted. hostname may be IP address, hostname, network/netmask, or network in CIDR format. db filename

Database file where login attempts are stored. trigger_cmd command

Command to run to block/unblock a host. See shield-trigger(8) and shield-trigger-iptables(8) for two examples. max_conns n

Host will be blocked if more than n connection attempts from one host in interval time. interval n

Host blocked if more than max_conns attempts in n seconds. Instead of seconds, suffix may be used: s for seconds, m minutes, h hours, d days, w weeks, M months (30 days), y years. retention n

Record of connection attempts retained for n seconds. Suffixes may be used as in interval. Each host is checked for expiration when it attempts to connect, and the entire database is checked whenever shield-purge(8) is run (by default, once a day).


/etc/security/shield.conf Configuration file for pam-shield

RELATED TO shield.conf…


pam-shield was written by and copyright 2007 Walter de Jong <[email protected]>. This manpage copyright 2010-2012 Jonathan Niehof <[email protected]>.