Hello! Given: a CentOS 8-powered computer with three network adapters. eth0, eth2: external, connected to two different ISPs eth1: faces home network (intranet) The task: allow accessing certain internal services from either ISP. There are several services, I only mention SSH below. In the configs below: IP1: external IP at first ISP (ISP1), assigned to eth0 Gateway1: IP of gateway provided by ISP1 Network1,Netmask1: related to IP1 IP2: external IP at second ISP (ISP2), assigned to eth2 Gateway2: IP of gateway provided by ISP2 Network2,Netmask2: related to IP2 LocalSSHIP: IP in intranet (eth1) where SSH server is running Current configs follow. Routing tables: echo "200 isp1" >> /etc/iproute2/rt_tables echo "201 isp2" >> /etc/iproute2/rt_tables Routing policies: /etc/sysconfig/network-scripts/route-eth0 Network1 dev eth0 src IP1 table isp1 default via Gateway1 dev eth0 table isp1 /etc/sysconfig/network-scripts/route-eth2 Network2 dev eth2 src IP2 table isp2 default via Gateway2 dev eth2 table isp2 Routing rules: /etc/sysconfig/network-scripts/rule-eth0 from IP1/32 table isp1 /etc/sysconfig/network-scripts/rule-eth2 from IP2/32 table isp2 iptables snippets. External traffic forwarded to local SSH server from both interfaces: iptables -A PREROUTING -t nat -i eth0 -p tcp -d IP1 --dport 22 -j DNAT --to LocalSSHIP:22 iptables -A PREROUTING -t nat -i eth2 -p tcp -d IP2 --dport 22 -j DNAT --to LocalSSHIP:22 iptables -A FORWARD -p tcp -d LocalSSHIP --dport 22 -j ACCEPT eth0 is default gateway: $ ip route default via Gateway1 dev eth0 proto static metric 100 default via Gateway2 dev eth2 proto static metric 101 ... $ ip rule 0: from all lookup local 32764: from IP2 lookup isp2 32765: from IP1 lookup isp1 32766: from all lookup main 32767: from all lookup default SNAT is applied for the traffic originating from eth1: iptables -t nat -A POSTROUTING -i eth1 -o eth0 -j SNAT --to-source IP1 Current situation: - All services forwarded from eth0 are working normally. - All traffic originating from intranet passes out and back normally. - All the attempts to access services from eth2 time out. There are no obvious hints in /var/log/messages (such as complaints about "martian IPs"). I am somewhat at a loss here, all the pieces of advice would be very welcome. -- Sincerely, Konstantin Boyandin