I want to know if it's possible to block inbound traffic to a host but be able to send data only using 'route' command
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i'll take a guess here and say you cannot do it. routing is pretty much stateless - assuming that you have one ip address assigned to linux box you can indeed block bidirectional communication with given host by setting static route just for it pointing to... neverland. but such approach will block both communication initiated by your host or by foreign host.