methods on linux to block a host/network

block hosts

# some methods on *nix systems to block a host/network


# set a bogus arp address (for IPs in local subnet only)
arp -s 192.168.1.10 00:00:00:00:00:01


# blackhole this subnet
ip route add blackhole 192.168.2.0/24

# blackhole a host
ip route add blackhole 192.168.1.10/32


# iptables firewall block a host
iptables -I INPUT -s 192.168.1.10 -j DROP
iptables -I OUTPUT -d 192.168.1.10 -j DROP


# if you use UFW to manage iptables
ufw deny from 192.168.1.10 to any


# Add line below to /etc/hosts.deny 
# only works if server daemons are configured with tcpwrappers - more obsolete these days
ALL: 192.168.1.10