Super User Asked by cicekadam on July 26, 2020
I have two ethernet interfaces named enp1s0f0 and enp1s0f1. They have ip addresses from same subnet (don’t think it matters tho). Here is scenario:
My distro is Centos8
I have done "echo 1 > /proc/sys/net/ipv4/ip_forward"
enp1s0f0 has x.y.z.236
enp1s0f1 has x.y.z.237
i have written ip rule
[root@localhost ~]# ip rule list
0: from all lookup local
32762: from all to x.y.z.237 lookup 237
and my additional routing table 237
[root@localhost ~]# ip route list table 237
default via x.y.z.254 dev enp1s0f1
x.y.z.0/24 dev enp1s0f1 scope link src x.y.z.237
Here is my problem: first interface works well, for second interface i can see coming packets by tcpdump but nftables counters are not counting up. For example an ssh connection just go timeout. I have tried "meta nftrace set 1" for input and forward hooks but nothing passes here too.
Here is my tcpdump out:
[root@localhost ~]# tcpdump -i enp1s0f1 port 22 -n
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on enp1s0f1, link-type EN10MB (Ethernet), capture size 262144 bytes
17:13:01.305452 IP x.y.z.3.52229 > x.y.z.237.ssh: Flags [S], seq 2642985606, win 8192, options [mss 1428,nop,wscale 8,nop,nop,sackOK], length 0
17:13:04.305689 IP x.y.z.3.52229 > x.y.z.237.ssh: Flags [S], seq 2642985606, win 8192, options [mss 1428,nop,wscale 8,nop,nop,sackOK], length 0
17:13:10.306349 IP x.y.z.3.52229 > x.y.z.237.ssh: Flags [S], seq 2642985606, win 8192, options [mss 1428,nop,nop,sackOK], length 0
And here is my nftables rules:
table ip filter {
chain INPUT {
type filter hook input priority filter; policy accept;
ip daddr x.y.z.237 tcp dport 22 meta nftrace set 1 counter packets 0 bytes 0
chain FORWARD {
type filter hook forward priority filter; policy accept;
counter packets 0 bytes 0 accept
chain OUTPUT {
type filter hook output priority filter; policy accept;
ip saddr x.y.z.236 tcp sport 22 counter packets 383 bytes 102888 accept
ip saddr x.y.z.237 tcp sport 22 counter packets 0 bytes 0 accept
What am i missing? Where my packages go?
I figured it out. When I added ip rule add from x.y.z.237/32 table 237 it worked. Didn't understand why tho :D But it does the job, so no problem.
Answered by cicekadam on July 26, 2020
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