* Netfilter redirect does not work with wireguard
@ 2019-11-07 16:38 Nico Schottelius
2019-11-07 21:50 ` Ivan Labáth
0 siblings, 1 reply; 3+ messages in thread
From: Nico Schottelius @ 2019-11-07 16:38 UTC (permalink / raw)
To: WireGuard mailing list
Hello,
I am experimenting with nft / netfilter redirects to support wireguard
packets on *any* udp port. I tried using the following configuration for
nftables:
[17:34:14] vpn-2a0ae5c1:~# cat /etc/nftables.conf
#!/usr/sbin/nft -f
flush ruleset
table ip nat {
chain prerouting {
type nat hook prerouting priority 0;
# SSH works
tcp dport != 22 redirect to 22
# wireguard doesn't
udp dport != 51820 redirect to 51820
}
chain postrouting {
type nat hook postrouting priority 0;
}
}
However as you can see in the comments, this does not work with
wireguard, however it does work with SSH.
I can see that wireguard is kernel space, and ssh user space, but does
that cause the netfilter part to be skipped or am I doing some silly
mistake here?
Best regards,
Nico
--
Modern, affordable, Swiss Virtual Machines. Visit www.datacenterlight.ch
_______________________________________________
WireGuard mailing list
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https://lists.zx2c4.com/mailman/listinfo/wireguard
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Netfilter redirect does not work with wireguard
2019-11-07 16:38 Netfilter redirect does not work with wireguard Nico Schottelius
@ 2019-11-07 21:50 ` Ivan Labáth
2019-11-08 15:29 ` Nico Schottelius
0 siblings, 1 reply; 3+ messages in thread
From: Ivan Labáth @ 2019-11-07 21:50 UTC (permalink / raw)
To: Nico Schottelius; +Cc: WireGuard mailing list
Hello,
have you checked the source port of replies, or whether
there are any replies?
# tcpdump -nn
Tcpdump should show pre-NAT addresses on incoming packets
and AFAIK post-NAT on outgoing packets, i.e. what goes on
the wire.
You might need to apply SNAT on outgoing packets, which
might happen automatically with TCP connection tracking,
but I wouldn't really expect it on connection-less UDP.
Regards,
Ivan
On Thu, Nov 07, 2019 at 05:38:42PM +0100, Nico Schottelius wrote:
>
> Hello,
>
> I am experimenting with nft / netfilter redirects to support wireguard
> packets on *any* udp port. I tried using the following configuration for
> nftables:
>
> [17:34:14] vpn-2a0ae5c1:~# cat /etc/nftables.conf
> #!/usr/sbin/nft -f
>
> flush ruleset
>
> table ip nat {
> chain prerouting {
> type nat hook prerouting priority 0;
>
> # SSH works
> tcp dport != 22 redirect to 22
>
> # wireguard doesn't
> udp dport != 51820 redirect to 51820
> }
>
> chain postrouting {
> type nat hook postrouting priority 0;
> }
> }
>
> However as you can see in the comments, this does not work with
> wireguard, however it does work with SSH.
>
> I can see that wireguard is kernel space, and ssh user space, but does
> that cause the netfilter part to be skipped or am I doing some silly
> mistake here?
>
> Best regards,
>
> Nico
>
>
> --
> Modern, affordable, Swiss Virtual Machines. Visit www.datacenterlight.ch
> _______________________________________________
> WireGuard mailing list
> WireGuard@lists.zx2c4.com
> https://lists.zx2c4.com/mailman/listinfo/wireguard
_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Netfilter redirect does not work with wireguard
2019-11-07 21:50 ` Ivan Labáth
@ 2019-11-08 15:29 ` Nico Schottelius
0 siblings, 0 replies; 3+ messages in thread
From: Nico Schottelius @ 2019-11-08 15:29 UTC (permalink / raw)
To: Ivan Labáth; +Cc: WireGuard mailing list
Hello,
there are actually no replies at all, which is why I *assumed* that the
packets do not actually arrive at the wireguard code.
How does wireguard integrate into the kernel / netfilter flow? Or in
other words, how is the expected behaviour of something like what I am
trying to do?
Best,
Nico
p.s.: I was also thinking about needing SNAT, but I don't see any
replies generated at the moment.
Ivan Labáth <labawi-wg@matrix-dream.net> writes:
> Hello,
>
> have you checked the source port of replies, or whether
> there are any replies?
>
> # tcpdump -nn
>
> Tcpdump should show pre-NAT addresses on incoming packets
> and AFAIK post-NAT on outgoing packets, i.e. what goes on
> the wire.
>
> You might need to apply SNAT on outgoing packets, which
> might happen automatically with TCP connection tracking,
> but I wouldn't really expect it on connection-less UDP.
>
> Regards,
> Ivan
>
> On Thu, Nov 07, 2019 at 05:38:42PM +0100, Nico Schottelius wrote:
>>
>> Hello,
>>
>> I am experimenting with nft / netfilter redirects to support wireguard
>> packets on *any* udp port. I tried using the following configuration for
>> nftables:
>>
>> [17:34:14] vpn-2a0ae5c1:~# cat /etc/nftables.conf
>> #!/usr/sbin/nft -f
>>
>> flush ruleset
>>
>> table ip nat {
>> chain prerouting {
>> type nat hook prerouting priority 0;
>>
>> # SSH works
>> tcp dport != 22 redirect to 22
>>
>> # wireguard doesn't
>> udp dport != 51820 redirect to 51820
>> }
>>
>> chain postrouting {
>> type nat hook postrouting priority 0;
>> }
>> }
>>
>> However as you can see in the comments, this does not work with
>> wireguard, however it does work with SSH.
>>
>> I can see that wireguard is kernel space, and ssh user space, but does
>> that cause the netfilter part to be skipped or am I doing some silly
>> mistake here?
>>
>> Best regards,
>>
>> Nico
>>
>>
>> --
>> Modern, affordable, Swiss Virtual Machines. Visit www.datacenterlight.ch
>> _______________________________________________
>> WireGuard mailing list
>> WireGuard@lists.zx2c4.com
>> https://lists.zx2c4.com/mailman/listinfo/wireguard
--
Modern, affordable, Swiss Virtual Machines. Visit www.datacenterlight.ch
_______________________________________________
WireGuard mailing list
WireGuard@lists.zx2c4.com
https://lists.zx2c4.com/mailman/listinfo/wireguard
^ permalink raw reply [flat|nested] 3+ messages in thread
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