Unable to serve TCP connections over wireguard interface on FreeBSD 13.0-RC2

[Ashish]

Hi,

I'm running if_wg kernel module (git revision: 5ef4d3efa691e71) on
FreeBSD 13.0-RC2.

With 172.18.10.1 being my local host's wireguard interface's IP address,
I can receive SYN packets, but it does not seem to send any
corresponding SYN/ACK.

=========================
01:26:26.327484 IP 172.18[.10.3.34160 > 172.18.10.1.22: Flags [S], seq
1278197331, win 64860, options [mss 1380,sackOK,TS val 223949166 ecr
0,nop,wscale 7], length 0
01:26:42.708175 IP 172.18.10.3.34160 > 172.18.10.1.22: Flags [S], seq
1278197331, win 64860, options [mss 1380,sackOK,TS val 223965550 ecr
0,nop,wscale 7], length 0
01:27:14.964162 IP 172.18.10.3.34160 > 172.18.10.1.22: Flags [S], seq
1278197331, win 64860, options [mss 1380,sackOK,TS val 223997806 ecr
0,nop,wscale 7], length 0


01:28:34.035384 IP 172.18.10.2.41905 > 172.18.10.1.22: Flags [S], seq
2569759726, win 65535, options [mss 1380,nop,wscale 11,sackOK,TS val
3991744006 ecr 0], length 0
01:28:34.035392 IP 172.18.10.2.41905 > 172.18.10.1.22: Flags [S], seq
2569759726, win 65535, options [mss 1380,nop,wscale 11,sackOK,TS val
3991745042 ecr 0], length 0
01:28:34.036002 IP 172.18.10.2.41905 > 172.18.10.1.22: Flags [S], seq
2569759726, win 65535, options [mss 1380,nop,wscale 11,sackOK,TS val
3991747129 ecr 0], length 0
=========================

ICMP works fine:

=========================
01:53:15.638529 IP 172.18.10.2 > 172.18.10.1: ICMP echo request, id
47881, seq 0, length 64
01:53:15.638535 IP 172.18.10.1 > 172.18.10.2: ICMP echo reply, id 47881,
seq 0, length 64
01:53:16.624443 IP 172.18.10.2 > 172.18.10.1: ICMP echo request, id
47881, seq 1, length 64
01:53:16.624448 IP 172.18.10.1 > 172.18.10.2: ICMP echo reply, id 47881,
seq 1, length 64
01:53:17.672109 IP 172.18.10.2 > 172.18.10.1: ICMP echo request, id
47881, seq 2, length 64
01:53:17.672115 IP 172.18.10.1 > 172.18.10.2: ICMP echo reply, id 47881,
seq 2, length 64
01:53:18.676223 IP 172.18.10.2 > 172.18.10.1: ICMP echo request, id
47881, seq 3, length 64
01:53:18.676230 IP 172.18.10.1 > 172.18.10.2: ICMP echo reply, id 47881,
seq 3, length 64
01:53:19.682131 IP 172.18.10.2 > 172.18.10.1: ICMP echo request, id
47881, seq 4, length 64
01:53:19.682136 IP 172.18.10.1 > 172.18.10.2: ICMP echo reply, id 47881,
seq 4, length 64
=========================

And I can make outbound TCP connections:

=========================
01:50:43.267331 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [S], seq
2119392003, win 65535, options [mss 1380,nop,wscale 11,sackOK,TS val
1918472905 ecr 0], length 0
01:50:43.415524 IP 172.18.10.2.22 > 172.18.10.1.55541: Flags [S.], seq
2602046635, ack 2119392004, win 65535, options [mss 1380,nop,wscale
11,sackOK,TS val 1347987709 ecr 1918472905], length 0
01:50:43.415532 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [.], ack 1,
win 33, options [nop,nop,TS val 1918473053 ecr 1347987709], length 0
01:50:43.415613 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [P.], seq
1:31, ack 1, win 33, options [nop,nop,TS val 1918473053 ecr 1347987709],
length 30
01:50:43.614035 IP 172.18.10.2.22 > 172.18.10.1.55541: Flags [P.], seq
1:39, ack 31, win 33, options [nop,nop,TS val 1347987870 ecr
1918473053], length 38
01:50:43.653218 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [.], ack
39, win 33, options [nop,nop,TS val 1918473291 ecr 1347987870], length 0
01:50:43.693420 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [P.], seq
31:1055, ack 39, win 33, options [nop,nop,TS val 1918473331 ecr
1347987870], length 1024
01:50:43.693435 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [P.], seq
1055:1543, ack 39, win 33, options [nop,nop,TS val 1918473331 ecr
1347987870], length 488
01:50:43.818391 IP 172.18.10.2.22 > 172.18.10.1.55541: Flags [P.], seq
39:1119, ack 31, win 33, options [nop,nop,TS val 1347988093 ecr
1918473291], length 1080
01:50:43.819870 IP 172.18.10.1.55541 > 172.18.10.2.22: Flags [P.], seq
1543:1591, ack 1119, win 33, options [nop,nop,TS val 1918473457 ecr
1347988093], length 48
01:50:43.880995 IP 172.18.10.2.22 > 172.18.10.1.55541: Flags [.], ack
1543, win 33, options [nop,nop,TS val 1347988163 ecr 1918473331], length 0
01:50:43.991756 IP 172.18.10.2.22 > 172.18.10.1.55541: Flags [P.], seq
1119:1571, ack 1591, win 33, options [nop,nop,TS val 1347988277 ecr
1918473457], length 452
=========================



The tunnel is configured using `wg-quick'. The firewalls are unloaded
for this testing.
 I have made sure to delete the if_wg.ko shipped with FreeBSD, and
rebooted the host before trying this.



And ofcourse, if I switch to userspace Go implementation, everything
works as expected, keeping rest of the configuration same, and with
firewalls enabled.

Thanks!
-- 
Ashish

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