Routing between two Slackware network interfaces?

Question

linux

Good afternoon.
There is a PC with Slackware, it has 2 network cards
1: lo: mtu 16436 qdisc noqueue
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: eth0 : mtu 1500 qdisc pfifo_fast qlen 1000
inet 192.168.0.100 /24 brd 192.168.0.255 scope global eth0
valid_lft forever preferred_lft forever
3: eth1: mtu 1500 qdisc pfifo_fast qlen 1000
inet 10.1.1.206 /24 brd 10.1.1.255 scope global eth1
valid_lft forever preferred_lft forever
4: sit0: mtu 1480 qdisc noop
link/sit 0.0.0.0 brd 0.0.0.0
ip route show this PC
default via 10.1.1.30 dev eth1 metric 1
10.1.1.0/24 dev eth1 src 10.1.1.206
127.0.0.0/8 dev lo
192.168.0.0/24 dev eth0 src 192.168.0.100
10.1.1.30 is a Mikrotik, the Internet goes through it, the Route List contains the network 192.168.0.0/24 with the gateway 10.1.1.206
netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
0.0.0.0 10.1.1.30 0.0.0.0 UG 0 0 0 eth1
10.1.1.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1
192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
From the network port 192.168.0.100, the cable goes to 1 switch, PC 192.168.0.99 is connected to it, I register a gateway and DNS 192.168.0.100 on this PC, but they only kick 192.168.0.100, 10.1.1.206 and 10.1.1.30, everything else is not.
I need to get to the resource 10.1.1.210, it does not respond.
From the network 10.1.1.0/24, both 192.168.0.100 and the PC itself 192.168.0.99 are perfectly visible
Help me to set the route correctly, nothing comes out. Maybe Mikrotik is to blame?
iptables - no, Linux in minimal configuration.

Answer 1

In general, if you don’t understand why routing doesn’t work, draw your own diagram, it helps me personally.
a packet left point A) until 10.1.1.210 it went through the routing table 10.1.1.0/24 dev eth1 src 10.1.1.206 since the dst address matches the network address of this route .... draw)

Answer 2

I give you a hint. You need to enable ipv4-forward in sysctl.conf