Hi,
I have a Debian Host with FW & GW tasks for my LAN, and some Docker
containers inside.
I can see that Docker set some NFT rules for it's normal function. Rules
as these...
--------------------------------------------------------
table ip nat {
chain DOCKER {
iifname "br-fc93beb65b60" counter packets 0 bytes 0 return
iifname "docker0" counter packets 0 bytes 0 return
iifname != "br-fc93beb65b60" tcp dport 3306 counter
packets 0 bytes 0 dnat to 172.22.0.33:3306
...
}
chain POSTROUTING {
type nat hook postrouting priority srcnat; policy accept;
oifname != "br-fc93beb65b60" ip saddr 172.22.0.0/24
counter packets 778 bytes 63705 masquerade
oifname != "docker0" ip saddr 172.17.0.0/16 counter
packets 0 bytes 0 masquerade
ip saddr 172.22.0.33 ip daddr 172.22.0.33 tcp dport
3306 counter packets 0 bytes 0 masquerade
...
}
chain PREROUTING {
type nat hook prerouting priority dstnat; policy accept;
fib daddr type local counter packets 53594 bytes
3220837 jump DOCKER
}
chain OUTPUT {
type nat hook output priority -100; policy accept;
ip daddr != 127.0.0.0/8 fib daddr type local counter
packets 0 bytes 0 jump DOCKER
}
}
table ip filter {
chain DOCKER {
iifname != "br-fc93beb65b60" oifname "br-fc93beb65b60"
ip daddr 172.22.0.33 tcp dport 3306 counter packets 0 bytes 0 accept
...
}
chain DOCKER-ISOLATION-STAGE-1 {
iifname "br-fc93beb65b60" oifname != "br-fc93beb65b60"
counter packets 284122 bytes 276578066 jump DOCKER-ISOLATION-STAGE-2
iifname "docker0" oifname != "docker0" counter packets
0 bytes 0 jump DOCKER-ISOLATION-STAGE-2
counter packets 596380 bytes 316649936 return
}
chain DOCKER-ISOLATION-STAGE-2 {
oifname "br-fc93beb65b60" counter packets 0 bytes 0 drop
oifname "docker0" counter packets 0 bytes 0 drop
counter packets 284122 bytes 276578066 return
}
chain FORWARD {
type filter hook forward priority filter; policy drop;
counter packets 596379 bytes 316649852 jump DOCKER-USER
counter packets 596379 bytes 316649852 jump
DOCKER-ISOLATION-STAGE-1
oifname "br-fc93beb65b60" ct state related,established
counter packets 245582 bytes 35730696 accept
oifname "br-fc93beb65b60" counter packets 54022 bytes
3255121 jump DOCKER
iifname "br-fc93beb65b60" oifname != "br-fc93beb65b60"
counter packets 284122 bytes 276578066 accept
iifname "br-fc93beb65b60" oifname "br-fc93beb65b60"
counter packets 385 bytes 25909 accept
oifname "docker0" ct state related,established counter
packets 0 bytes 0 accept
oifname "docker0" counter packets 0 bytes 0 jump DOCKER
iifname "docker0" oifname != "docker0" counter packets
0 bytes 0 accept
iifname "docker0" oifname "docker0" counter packets 0
bytes 0 accept
}
chain DOCKER-USER {
counter packets 596380 bytes 316649936 return
}
}
--------------------------------------------------------
I suppose these rules make NAT and Block functions for Docker
containers. But I have my own rules for NAT and Block to my Devices in
my LAN too, for example, with rules as these...
--------------------------------------------------------
table ip alb-nat {
chain PREROUTING {
type nat hook prerouting priority 30; policy accept;
}
chain POSTROUTING {
type nat hook postrouting priority 30; policy accept;
oifname "eth0" ip saddr 192.168.9.0/24 masquerade
}
}
table inet alb-fw {
chain BASE_CHECKS {
ct state established,related,new accept
ct state invalid drop
}
chain INPUT {
type filter hook input priority filter + 10; policy drop;
jump BASE_CHECKS
iifname "lo" accept
iifname "br0" ip saddr 192.168.9.0/24 counter packets
0 bytes 0 accept
log prefix "[NFTABLES] Denied " flags all
}
chain FORWARD {
type filter hook forward priority filter + 10; policy
accept;
jump BASE_CHECKS
iifname "br0" oifname "eth0" meta l4proto { tcp, udp }
ip saddr 192.168.9.0/24 accept
}
chain OUTPUT {
type filter hook output priority filter + 10; policy
accept;
jump BASE_CHECKS
}
}
--------------------------------------------------------
I can see that Systemd service have a Flush rule, but in STOP phase...
[Service]
Type=oneshot
...
ExecStop=/usr/sbin/nft flush ruleset
they also have the rules in different tables. I guess they shouldn't
collide. However, when system boots, I can see all rules active, but my
laptop (it's a LAN device which receive Dynamic DHCP and Internet output
from Debian Host) cannot ping to outside:
$ ping www.google.com
PING www.google.com (172.217.168.164) 56(84) bytes of data.
If I restart NFTABLES service...
# systemctl restart nftables
Docker tables disappear, and I can ping to outside:
$ ping www.google.com
PING www.google.com (172.217.168.164) 56(84) bytes of data.
64 bytes from mad07s10-in-f4.1e100.net (172.217.168.164): icmp_seq=1
ttl=115 time=10.4
64 bytes from mad07s10-in-f4.1e100.net (172.217.168.164): icmp_seq=2
ttl=115 time=10.3
...
If I restart Docker service, Docker tables appears, and ping follow running.
I'm trying to set docker.service as dependency of nftables.service, for
start docker before nft, of this way:
# cat /lib/systemd/system/nftables.service
[Unit]
Description=nftables
Documentation=man:nft(8) http://wiki.nftables.org
Wants=network-pre.target *** _*docker.service*_ ***
Before=network-pre.target shutdown.target
Conflicts=shutdown.target
DefaultDependencies=no
[Service]
Type=oneshot
RemainAfterExit=yes
StandardInput=null
ProtectSystem=full
ProtectHome=true
ExecStart=/usr/sbin/nft -f /etc/nftables.conf
ExecReload=/usr/sbin/nft -f /etc/nftables.conf
ExecStop=/usr/sbin/nft flush ruleset
but it's not working.
I don't know what's is the best solution for this.
Best Regards,
Alberto
