DROP or REJECT packets from PREROUTING NAT table in iptables

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Goal is to allow only specific networks to access docker container services/ports running on my server.



Tried adding ACCEPT rules in to INPUT filter chain. That did not help, networks even without ACCEPT rule were still able to access docker service/port.



Tried adding ACCEPT and DROP rules in FORWARD chain, this works. But this has many disadvantages like: a. Rules getting deleted or re-positioned on docker restart b. Rules can become invalid, if docker containers are re-deployed and get different IPs at runtime



Plan is to BLOCK them before even reaching FORWARD chain.



So, added a new chain in NAT table, which redirects to DOCKER chain if traffic is from allowed network, if it is from other networks, added DNAT to a BLOCKHOLE IP. In PREROUTING, first rule is to jump to this chain.This seems to be working.



DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:0.0.0.1



But, instead of redirecting it to a BLOCKHOLE, can we somehow REJECT this traffic so that the client knows it is not allowed and hence refused.






iptables nat







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  • Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
    – Ram
    Aug 31 at 10:10














up vote
1
down vote

favorite












Goal is to allow only specific networks to access docker container services/ports running on my server.



Tried adding ACCEPT rules in to INPUT filter chain. That did not help, networks even without ACCEPT rule were still able to access docker service/port.



Tried adding ACCEPT and DROP rules in FORWARD chain, this works. But this has many disadvantages like: a. Rules getting deleted or re-positioned on docker restart b. Rules can become invalid, if docker containers are re-deployed and get different IPs at runtime



Plan is to BLOCK them before even reaching FORWARD chain.



So, added a new chain in NAT table, which redirects to DOCKER chain if traffic is from allowed network, if it is from other networks, added DNAT to a BLOCKHOLE IP. In PREROUTING, first rule is to jump to this chain.This seems to be working.



DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:0.0.0.1



But, instead of redirecting it to a BLOCKHOLE, can we somehow REJECT this traffic so that the client knows it is not allowed and hence refused.






iptables nat







share|improve this question





















  • Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
    – Ram
    Aug 31 at 10:10












up vote
1
down vote

favorite









up vote
1
down vote

favorite











Goal is to allow only specific networks to access docker container services/ports running on my server.



Tried adding ACCEPT rules in to INPUT filter chain. That did not help, networks even without ACCEPT rule were still able to access docker service/port.



Tried adding ACCEPT and DROP rules in FORWARD chain, this works. But this has many disadvantages like: a. Rules getting deleted or re-positioned on docker restart b. Rules can become invalid, if docker containers are re-deployed and get different IPs at runtime



Plan is to BLOCK them before even reaching FORWARD chain.



So, added a new chain in NAT table, which redirects to DOCKER chain if traffic is from allowed network, if it is from other networks, added DNAT to a BLOCKHOLE IP. In PREROUTING, first rule is to jump to this chain.This seems to be working.



DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:0.0.0.1



But, instead of redirecting it to a BLOCKHOLE, can we somehow REJECT this traffic so that the client knows it is not allowed and hence refused.






iptables nat







share|improve this question













Goal is to allow only specific networks to access docker container services/ports running on my server.



Tried adding ACCEPT rules in to INPUT filter chain. That did not help, networks even without ACCEPT rule were still able to access docker service/port.



Tried adding ACCEPT and DROP rules in FORWARD chain, this works. But this has many disadvantages like: a. Rules getting deleted or re-positioned on docker restart b. Rules can become invalid, if docker containers are re-deployed and get different IPs at runtime



Plan is to BLOCK them before even reaching FORWARD chain.



So, added a new chain in NAT table, which redirects to DOCKER chain if traffic is from allowed network, if it is from other networks, added DNAT to a BLOCKHOLE IP. In PREROUTING, first rule is to jump to this chain.This seems to be working.



DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:0.0.0.1



But, instead of redirecting it to a BLOCKHOLE, can we somehow REJECT this traffic so that the client knows it is not allowed and hence refused.






iptables nat




iptables nat






share|improve this question













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asked Aug 31 at 9:36









Ram

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126113











  • Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
    – Ram
    Aug 31 at 10:10
















  • Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
    – Ram
    Aug 31 at 10:10















Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
– Ram
Aug 31 at 10:10




Tried: DNAT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:1234 to:<Server-IP> And catch the same port traffic in INPUT filter and DROP/REJECT. Even then the client gets 'Connection Timedout'. So its same behavior even if we direct the traffic to a BLOCKHOLE.
– Ram
Aug 31 at 10:10















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