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At my job we have a script which will block traffic from an IP address. &nbsp;For example, for an IP address = A.B.C.D the script would execute this command:<br />
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/sbin/route add -net A.B.C.0 netmask 255.255.255.0 lo<br />
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Can anybody explain how this works? &nbsp;I have been tring to understand why this should block the traffic from the IP but I don't understand.<br />
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We are using Redhat linux version 7.2. &nbsp;If the server's gateway were 1.1.1.1 then this would be the routing table:<br />
Kernel IP routing table<br />
Destination &nbsp; &nbsp; Gateway &nbsp; &nbsp; &nbsp; &nbsp; Genmask &nbsp; &nbsp; &nbsp; &nbsp; Flags &nbsp; MSS Window &nbsp;irtt Iface<br />
1.1.1.0 &nbsp; &nbsp; 0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; 255.255.240.0 &nbsp; U &nbsp; &nbsp; &nbsp; &nbsp; 0 0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0 eth0<br />
127.0.0.0 &nbsp; &nbsp; &nbsp; 0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; 255.0.0.0 &nbsp; &nbsp; &nbsp; U &nbsp; &nbsp; &nbsp; &nbsp; 0 0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0 lo<br />
0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; 1.1.1.1 &nbsp; &nbsp; 0.0.0.0 &nbsp; &nbsp; &nbsp; &nbsp; UG &nbsp; &nbsp; &nbsp; &nbsp;0 0 &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;0 eth0
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At my job we have a script which will block traffic from an IP address.  For example, for an IP address = A.B.C.D the script would execute this command:

/sbin/route add -net A.B.C.0 netmask 255.255.255.0 lo

Can anybody explain how this works?  I have been tring to understand why this should block the traffic from the IP but I don't understand.

We are using Redhat linux version 7.2.  If the server's gateway were 1.1.1.1 then this would be the routing table:
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
1.1.1.0     0.0.0.0         255.255.240.0   U         0 0          0 eth0
127.0.0.0       0.0.0.0         255.0.0.0       U         0 0          0 lo
0.0.0.0         1.1.1.1     0.0.0.0         UG        0 0          0 eth0

linux routing question

The variety of Linux distributions creates myriad issues relating to configuration and operations when computers are networked, not the least of which is the use of various network management applications, some of which are included with specific distributions, while others are standalone applications.