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This page is a translated version of the page Sshguard and the translation is 31% complete.
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sshguard is an intrusion prevention system that parses server logs, determines malicious activity, and uses the system firewall to block the IP addresses of malicious connections. sshguard is written in C so it does not tax an interpreter.

எவ்வாறு வேலை செய்கிறது

sshguard is a simple daemon that continuously tracks one or more log files. It parses the log events that daemons send out in case of failed login attempts and then blocks any further attempts from those connections by updating the system's firewall.

Unlike what the name implies, sshguard does not only parse SSH logs. It also supports many mail systems as well as a few FTP ones. A full listing of supported services can be found on the website.


இ-ஒன்றாக்குதல் (Emerge)

app-admin/sshguard தொகுப்பை நிறுவவும்:

root #emerge --ask app-admin/sshguard

Also make sure that net-firewall/iptables is installed and used as the system firewall. At the time of writing, sshguard does not yet support net-firewall/nftables.

root #emerge --ask net-firewall/iptables

IP அட்டவணைகளைப் பயன்படுத்துதல் மற்றும் உள்ளமைத்தல் பற்றிய மேலும் தகவல்களுக்கு IP அட்டவணை கட்டுரையை காணவும்.


தீயரணை ஆயத்தப்படுத்துதல்

When sshguard blocks any malicious users (by blocking their IP addresses), it will use the sshguard chain.

Prepare the chain, and make sure it is also triggered when new incoming connections are detected:

root #iptables -N sshguard
root #iptables -A INPUT -j sshguard

குறிப்புப்பதிவு கோப்புகளைப் பார்த்தல்

The basic idea behind sshguard is that the administrator passes on the log file(s) to watch as options to the application - there is no native sshguard configuration file.

ஜென்டூவில், விருப்பத்தேர்வுகளை /etc/sshguard.conf கோப்பில் சிறப்பாக உள்ளமைக்க இயலும்:

கோப்பு /etc/sshguard.conf/var/log/messages மற்றும் /var/log/auth.log களை படிப்பதற்கு sshguard ஐ உள்ளமைத்தல்
# பின்நிலை செயல்படுத்தகு நிரலுக்கான முழு பாதை (தேவைப்படுகிறது, முன்னிருப்பு எதுவும் இல்லை)

# இடைவெளியால் பிரிக்கப்பட்ட, கண்காணிக்கப்பட வேண்டிய குறிப்புப்பதிவு கோப்புகளின் பட்டியல். (விரும்பினால், முன்னிருப்பு எதுவும் இல்லை)
FILES="/var/log/messages /var/log/auth.log" 

# How many problematic attempts trigger a block
# Blocks last at least 24 hours (60480 seconds)
# Track IP addresses for 24 hours (60480 seconds)

# IPv6 subnet size to block. Defaults to a single address, CIDR notation. (optional, default to 128)
# IPv4 subnet size to block. Defaults to a single address, CIDR notation. (optional, default to 32)

# PID கோப்பிற்கான முழு பாதை (விரும்பினால், முன்னிருப்பு எதுவும் இல்லை)

Make sure that the log files are accessible for the runtime user that sshguard uses.



Have sshguard be started by default by adding it to the default runlevel, and then start it:

root #rc-update add sshguard default
root #rc-service sshguard start

Blacklisting hosts

With the blacklisting option after a number of abuses the IP address of the attacker or a IP subnet will be blocked permanently. The blacklist will be loaded at each startup and extended with new entries during operation. sshguard inserts a new address after it exceeded a threshold of abuses.

Blacklisted addresses are never scheduled to be released (allowed) again.

To enable blacklisting, create an appropriate directory and file:

root #mkdir -p /var/lib/sshguard
root #touch /var/lib/sshguard/blacklist.db

While defining a blacklist it is important to exclude trusted IP networks and hosts in a whitelist.

To enable whitelisting, create an appropriate directory and file:

root #mkdir -p /etc/sshguard
root #touch /etc/sshguard/whitelist

The whitelist has to include the loopback interface, and should have at least 1 IP trusted network f.e.

FILE /etc/sshguard/whitelistWhitelisting trusted networks
The entry has to be adjusted to fit the own needs.

Add the BLACKLIST_FILE and WHITELIST_FILE file to the configuration:

FILE /etc/conf.d/sshguardConfiguring sshguard to blacklist abusers




# Add following lines

Restart the sshguard daemon to have the changes take effect:

root #/etc/init.d/sshguard restart


File '/var/log/auth.log' vanished while adding!

When starting up, sshguard reports the following error:

CODE Error message when trying to add a monitor for /var/log/auth.log
Sep 23 03:39:11 sshguard[64933]: File '/var/log/auth.log' vanished while adding!

Such an error (the file path itself can be different) occurs when the target file is not available on the system. Make sure that it is created, or update the sshguard configuration to not add it for monitoring.

On a syslog-ng system with OpenRC, the following addition to syslog-ng.conf can suffice:

FILE /etc/syslog-ng/syslog-ng.confcreating auth.log file
log { source(src); destination(messages); };
log { source(src); destination(console_all); };
destination authlog {file("/var/log/auth.log"); };
filter f_auth { facility(auth); };
filter f_authpriv { facility(auth, authpriv); };
log { source(src);  filter(f_authpriv);  destination(authlog);  };

Reload the configuration for the changes to take effect:

root #rc-service syslog-ng reload

See also

  • Iptables - An article on installing and configuring the iptables firewall on Gentoo.

External resources

The sshguard documentation provides all the information needed to further tune the application.