Incoming connections on l2tp

[Kadir]

I can't connect to the second address at the l2tp. udp echo has tried - only from one Internet.

Answers the wrong address.

iptables -t mangle

-A PREROUTING -i enp0s10 -j CONNMARK --set-xmark 0x64/0xffffffff
-A PREROUTING -i enp0s18 -j CONNMARK --set-xmark 0x65/0xffffffff
-A OUTPUT -j CONNMARK --restore-mark --nfmask 0xffffffff --ctmask 0xffffffff

ip ru l

0:  from all lookup local 
219:    from all fwmark 0x64 lookup 100 
32762:  from 81.хх.хх.12 lookup 100 
32764:  from all fwmark 0x65 lookup 101 
32765:  from 109.yy.yy.13 lookup 101 
32766:  from all lookup main 
32767:  from all lookup default 

ip ro l table 100

default via 81.хх.хх.1 dev enp0s10 

ip ro l table 101

default via 109.yy.yy.1 dev enp0s18 

ip r l

default via 81.хх.хх.1 dev enp0s10 metric 20 
default via 109.yy.yy.1 dev enp0s18 metric 21 onlink 
81.xx.xx.0/24 dev enp0s10 proto kernel scope link src 81.хх.хх.12
109.yy.yy.0/24 dev enp0s18 proto kernel scope link src 109.yy.yy.13
192.168.0.0/24 dev enp0s8 proto kernel scope link src 192.168.0.1 

What?

I did, until helped.

ip r a 81.хх.хх.0/24 dev enp0s10 proto kernel scope link src 81.хх.хх.12 table 100
ip r a 109.yy.yy.0/24 dev enp0s18 proto kernel scope link src 109.yy.yy.13 table 101

In contrast, the mark is placed

conntrack -L | grep mark=101 | grep 213.87.138.134
conntrack v1.4.4 (conntrack-tools): 1064 flow entries have been shown.
udp      17 178 src=213.87.138.134 dst=109.yy.yy.13 sport=44009 dport=1701 src=109.yy.yy.13 dst=213.87.138.134 sport=1701 dport=44009 [ASSURED] mark=101 use=1

Not helpful.

iptables -t mangle -A PREROUTING -i enp0s18 -j CONNMARK --save-mark

Not helpful.

sysctl net.ipv4.fwmark_reflect=1

The problem is that the udp network grids take an out-of-the-shelf response, not from the counter.

[Anderson]

Received the UDP response from the required sorce to the unnecessary:

iptables -t nat -I PREROUTING -i enp0s18 -p udp --dport 1235 -j DNAT --to-destination 81.хх.хх.12