This is an example.

Again the TCP 3 handshake completes , but the next packet fails to NAT
and goes out onto the physical network using the private address .  An
example of this is in the packet trace I provided.


ovs-appctl ofproto/trace br-int
in_port=7753,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,tcp,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_ttl=32,tcp_src=52776,tcp_dst=443,tcp_flags=2
Flow: 
tcp,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=32,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn

bridge("br-int")
----------------
 0. in_port=7753, priority 100, cookie 0xc33f39c4
    set_field:0x16d->reg13
    set_field:0x155->reg11
    set_field:0x1cf->reg12
    set_field:0x12->metadata
    set_field:0xca->reg14
    resubmit(,8)
 8. metadata=0x12, priority 50, cookie 0x1645d3f2
    set_field:0/0x1000->reg10
    resubmit(,73)
    73. 
ip,reg14=0xca,metadata=0x12,dl_src=4e:42:14:a1:2a:fb,nw_src=172.27.18.244,
priority 90, cookie 0xc33f39c4
            set_field:0/0x1000->reg10
    move:NXM_NX_REG10[12]->NXM_NX_XXREG0[111]
     -> NXM_NX_XXREG0[111] is now 0
    resubmit(,9)
 9. metadata=0x12, priority 0, cookie 0xcc4fd106
    resubmit(,10)
10. metadata=0x12, priority 0, cookie 0x9e10ad0e
    resubmit(,11)
11. metadata=0x12, priority 0, cookie 0x557f3249
    resubmit(,12)
12. ip,metadata=0x12, priority 100, cookie 0x14131a67
    set_field:0x1000000000000000000000000/0x1000000000000000000000000->xxreg0
    resubmit(,13)
13. metadata=0x12, priority 0, cookie 0x85f9ed4f
    resubmit(,14)
14. ip,reg0=0x1/0x1,metadata=0x12, priority 100, cookie 0x279651c
    ct(table=15,zone=NXM_NX_REG13[0..15])
    drop
     -> A clone of the packet is forked to recirculate. The forked
pipeline will be resumed at table 15.
     -> Sets the packet to an untracked state, and clears all the
conntrack fields.

Final flow: 
tcp,reg0=0x1,reg11=0x155,reg12=0x1cf,reg13=0x16d,reg14=0xca,metadata=0x12,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=32,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn
Megaflow: 
recirc_id=0,eth,tcp,in_port=7753,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_frag=no
Datapath actions: ct(zone=365),recirc(0x13b5a)

===============================================================================
recirc(0x13b5a) - resume conntrack with default ct_state=trk|new (use
--ct-next to customize)
===============================================================================

Flow: 
recirc_id=0x13b5a,ct_state=new|trk,ct_zone=365,eth,tcp,reg0=0x1,reg11=0x155,reg12=0x1cf,reg13=0x16d,reg14=0xca,metadata=0x12,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=32,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn

bridge("br-int")
----------------
    thaw
        Resuming from table 15
15. ct_state=+new-est+trk,metadata=0x12, priority 7, cookie 0xa9e0ee6f
    set_field:0x80000000000000000000000000/0x80000000000000000000000000->xxreg0
    
set_field:0x200000000000000000000000000/0x200000000000000000000000000->xxreg0
    resubmit(,16)
16. conj_id=2865573479,tcp,reg0=0x80/0x80,reg14=0xca,metadata=0x12,
priority 3000, cookie 0xabdec111
    set_field:0x1000000000000/0x1000000000000->xreg4
    set_field:0x2000000000000000000000000/0x2000000000000000000000000->xxreg0
    resubmit(,17)
17. reg8=0x10000/0x10000,metadata=0x12, priority 1000, cookie 0x8171c04a
    set_field:0/0x1000000000000->xreg4
    set_field:0/0x2000000000000->xreg4
    set_field:0/0x4000000000000->xreg4
    resubmit(,18)
18. metadata=0x12, priority 0, cookie 0x62454929
    resubmit(,19)
19. metadata=0x12, priority 0, cookie 0x3bb47080
    resubmit(,20)
20. metadata=0x12, priority 0, cookie 0x73face9d
    resubmit(,21)
21. metadata=0x12, priority 0, cookie 0x8e46634d
    resubmit(,22)
22. metadata=0x12, priority 0, cookie 0xbddac461
    resubmit(,23)
23. metadata=0x12, priority 0, cookie 0x9a32c0de
    resubmit(,24)
24. metadata=0x12, priority 0, cookie 0x79b1c074
    resubmit(,25)
25. metadata=0x12, priority 0, cookie 0xc02374d3
    resubmit(,26)
26. metadata=0x12, priority 0, cookie 0x218dc750
    resubmit(,27)
27. metadata=0x12, priority 0, cookie 0xf6943631
    set_field:0/0x1000000000000->xreg4
    set_field:0/0x2000000000000->xreg4
    set_field:0/0x4000000000000->xreg4
    resubmit(,28)
28. ip,reg0=0x2/0x2002,metadata=0x12, priority 100, cookie 0x7fdca4fb
    ct(commit,zone=NXM_NX_REG13[0..15],nat(src),exec(set_field:0/0x1->ct_mark))
    nat(src)
    set_field:0/0x1->ct_mark
     -> Sets the packet to an untracked state, and clears all the
conntrack fields.
    resubmit(,29)
29. metadata=0x12, priority 0, cookie 0x34e5fac7
    resubmit(,30)
30. metadata=0x12, priority 0, cookie 0xac3f53bd
    resubmit(,31)
31. metadata=0x12, priority 0, cookie 0x54000bd5
    resubmit(,32)
32. metadata=0x12, priority 0, cookie 0x29ab49f3
    resubmit(,33)
33. metadata=0x12, priority 0, cookie 0xae6aefcb
    resubmit(,34)
34. metadata=0x12, priority 0, cookie 0x632dc93b
    resubmit(,35)
35. metadata=0x12,dl_dst=1a:16:b1:58:e1:cd, priority 50, cookie 0x3fa33935
    set_field:0x1->reg15
    resubmit(,37)
37. priority 0
    resubmit(,39)
39. priority 0
    resubmit(,40)
40. reg15=0x1,metadata=0x12, priority 100, cookie 0x95c785db
    set_field:0x155->reg11
    set_field:0x1cf->reg12
    resubmit(,41)
41. priority 0
    set_field:0->reg0
    set_field:0->reg1
    set_field:0->reg2
    set_field:0->reg3
    set_field:0->reg4
    set_field:0->reg5
    set_field:0->reg6
    set_field:0->reg7
    set_field:0->reg8
    set_field:0->reg9
    resubmit(,42)
42. ip,reg15=0x1,metadata=0x12, priority 110, cookie 0xc9a79824
    resubmit(,43)
43. ip,reg15=0x1,metadata=0x12, priority 110, cookie 0xac7d5d78
    resubmit(,44)
44. metadata=0x12, priority 0, cookie 0xa1ddb4f6
    resubmit(,45)
45. ct_state=-trk,metadata=0x12, priority 5, cookie 0xb2622a65
    
set_field:0x100000000000000000000000000/0x100000000000000000000000000->xxreg0
    
set_field:0x200000000000000000000000000/0x200000000000000000000000000->xxreg0
    resubmit(,46)
46. metadata=0x12, priority 0, cookie 0x267ae0e3
    resubmit(,47)
47. metadata=0x12, priority 0, cookie 0x914392c3
    set_field:0/0x1000000000000->xreg4
    set_field:0/0x2000000000000->xreg4
    set_field:0/0x4000000000000->xreg4
    resubmit(,48)
48. metadata=0x12, priority 0, cookie 0xc4f6a97f
    resubmit(,49)
49. metadata=0x12, priority 0, cookie 0x8ebb0c71
    resubmit(,50)
50. metadata=0x12, priority 0, cookie 0x61e385f4
    resubmit(,51)
51. metadata=0x12, priority 0, cookie 0x4c722ce1
    set_field:0/0x1000->reg10
    resubmit(,75)
    75. No match.
            drop
    move:NXM_NX_REG10[12]->NXM_NX_XXREG0[111]
     -> NXM_NX_XXREG0[111] is now 0
    resubmit(,52)
52. metadata=0x12, priority 0, cookie 0x3c01b89d
    resubmit(,64)
64. priority 0
    resubmit(,65)
65. reg15=0x1,metadata=0x12, priority 100, cookie 0x95c785db
    
clone(ct_clear,set_field:0->reg11,set_field:0->reg12,set_field:0->reg13,set_field:0x4cc->reg11,set_field:0x383->reg12,set_field:0x13->metadata,set_field:0x1->reg14,set_field:0->reg10,set_field:0->reg15,set_field:0->reg0,set_field:0->reg1,set_field:0->reg2,set_field:0->reg3,set_field:0->reg4,set_field:0->reg5,set_field:0->reg6,set_field:0->reg7,set_field:0->reg8,set_field:0->reg9,resubmit(,8))
    ct_clear
    set_field:0->reg11
    set_field:0->reg12
    set_field:0->reg13
    set_field:0x4cc->reg11
    set_field:0x383->reg12
    set_field:0x13->metadata
    set_field:0x1->reg14
    set_field:0->reg10
    set_field:0->reg15
    set_field:0->reg0
    set_field:0->reg1
    set_field:0->reg2
    set_field:0->reg3
    set_field:0->reg4
    set_field:0->reg5
    set_field:0->reg6
    set_field:0->reg7
    set_field:0->reg8
    set_field:0->reg9
    resubmit(,8)
 8. reg14=0x1,metadata=0x13,dl_dst=1a:16:b1:58:e1:cd, priority 50,
cookie 0x8522832c
    
set_field:0x1a16b158e1cd0000000000000000/0xffffffffffff0000000000000000->xxreg0
    resubmit(,9)
 9. metadata=0x13, priority 0, cookie 0xef4dd8a9
    set_field:0x4/0x4->xreg4
    resubmit(,10)
10. reg9=0x4/0x4,metadata=0x13, priority 100, cookie 0x37718dd7
    resubmit(,79)
    79. 
ip,reg14=0x1,metadata=0x13,dl_src=4e:42:14:a1:2a:fb,nw_src=172.27.18.244,
priority 100, cookie 0x2e544767
            drop
    resubmit(,11)
11. metadata=0x13, priority 0, cookie 0x3c2eb1b
    resubmit(,12)
12. metadata=0x13, priority 0, cookie 0x44f62446
    resubmit(,13)
13. metadata=0x13, priority 0, cookie 0x3842bec6
    resubmit(,14)
14. metadata=0x13, priority 0, cookie 0xfd7b2ab9
    resubmit(,15)
15. metadata=0x13, priority 0, cookie 0xefbd7e27
    resubmit(,16)
16. metadata=0x13, priority 0, cookie 0xf439d853
    resubmit(,17)
17. metadata=0x13, priority 0, cookie 0x123f01f0
    resubmit(,18)
18. metadata=0x13, priority 0, cookie 0x142cd59b
    resubmit(,19)
19. metadata=0x13, priority 0, cookie 0x297e0190
    resubmit(,20)
20. metadata=0x13, priority 0, cookie 0x61e9e3c7
    set_field:0/0xffffffff->xxreg1
    resubmit(,21)
21. ip,reg7=0,metadata=0x13, priority 1, cookie 0x9f114f3d
    dec_ttl()
    set_field:0/0xffff00000000->xreg4
    
set_field:0x64646401000000000000000000000000/0xffffffff000000000000000000000000->xxreg0
    set_field:0x646464030000000000000000/0xffffffff0000000000000000->xxreg0
    set_field:2a:d5:d1:e8:89:cc->eth_src
    set_field:0x2->reg15
    set_field:0x1/0x1->reg10
    resubmit(,22)
22. reg8=0/0xffff,metadata=0x13, priority 150, cookie 0x6ece899a
    resubmit(,23)
23. metadata=0x13, priority 0, cookie 0x72437536
    set_field:0/0xffff00000000->xreg4
    resubmit(,24)
24. reg8=0/0xffff,metadata=0x13, priority 150, cookie 0xce06f1
    resubmit(,25)
25. ip,metadata=0x13, priority 1, cookie 0xf690342c
    push:NXM_NX_REG0[]
    push:NXM_NX_XXREG0[96..127]
    pop:NXM_NX_REG0[]
     -> NXM_NX_REG0[] is now 0x64646401
    set_field:00:00:00:00:00:00->eth_dst
    resubmit(,66)
    66. reg0=0x64646401,reg15=0x2,metadata=0x13, priority 100, cookie 0x97b4353d
            set_field:00:00:5e:00:01:ff->eth_dst
            set_field:0x40/0x40->reg10
    pop:NXM_NX_REG0[]
     -> NXM_NX_REG0[] is now 0x64646401
    resubmit(,26)
26. metadata=0x13, priority 0, cookie 0x6c2ad4cc
    resubmit(,27)
27. metadata=0x13, priority 0, cookie 0xadc9fb4f
    resubmit(,28)
28. ip,reg15=0x2,metadata=0x13,nw_src=172.27.18.244, priority 100,
cookie 0xfa923492
    set_field:4e:42:14:a1:2a:fb->eth_src
    set_field:0xcc3418740000000000000000/0xffffffff0000000000000000->xxreg0
    resubmit(,29)
29. metadata=0x13, priority 0, cookie 0x571bbf77
    resubmit(,37)
37. priority 0
    resubmit(,39)
39. priority 0
    resubmit(,40)
40. reg15=0x2,metadata=0x13, priority 100, cookie 0x407086d0
    set_field:0x4cc->reg11
    set_field:0x383->reg12
    resubmit(,41)
41. priority 0
    set_field:0->reg0
    set_field:0->reg1
    set_field:0->reg2
    set_field:0->reg3
    set_field:0->reg4
    set_field:0->reg5
    set_field:0->reg6
    set_field:0->reg7
    set_field:0->reg8
    set_field:0->reg9
    resubmit(,42)
42. metadata=0x13, priority 0, cookie 0x4c3b7fcc
    set_field:0/0x10->xreg4
    resubmit(,43)
43. ip,reg15=0x2,metadata=0x13,nw_src=172.27.18.244, priority 100,
cookie 0x540f90b2
    set_field:4e:42:14:a1:2a:fb->eth_src
    ct(table=44,zone=NXM_NX_REG11[0..15],nat)
    nat
     -> A clone of the packet is forked to recirculate. The forked
pipeline will be resumed at table 44.
     -> Sets the packet to an untracked state, and clears all the
conntrack fields.

Final flow: 
recirc_id=0x13b5a,eth,tcp,reg0=0x300,reg11=0x155,reg12=0x1cf,reg13=0x16d,reg14=0xca,reg15=0x1,metadata=0x12,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=32,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn
Megaflow: 
recirc_id=0x13b5a,ct_state=+new-est-rel-rpl-inv+trk,ct_mark=0/0x1,eth,tcp,in_port=7753,dl_src=4e:42:14:a1:2a:fb,dl_dst=1a:16:b1:58:e1:cd,nw_src=172.27.18.244,nw_dst=104.0.0.0/5,nw_ttl=32,nw_frag=no,tp_src=0x8000/0x8000,tp_dst=0x180/0xffc0
Datapath actions:
ct(commit,zone=365,mark=0/0x1,nat(src)),set(eth(dst=00:00:5e:00:01:ff)),set(ipv4(ttl=31)),ct(zone=1228,nat),recirc(0x13b5c)

===============================================================================
recirc(0x13b5c) - resume conntrack with default ct_state=trk|new (use
--ct-next to customize)
Replacing src/dst IP/ports to simulate NAT:
 Initial flow:
 Modified flow:
===============================================================================

Flow: 
recirc_id=0x13b5c,ct_state=new|trk,ct_zone=1228,eth,tcp,reg10=0x41,reg11=0x4cc,reg12=0x383,reg14=0x1,reg15=0x2,metadata=0x13,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=00:00:5e:00:01:ff,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=31,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn

bridge("br-int")
----------------
    thaw
        Resuming from table 44
44. metadata=0x13, priority 0, cookie 0x48ef0c42
    resubmit(,45)
45. ct_state=-rpl+trk,ip,reg15=0x2,metadata=0x13,nw_src=172.27.18.244,
priority 161, cookie 0x5414262a
    set_field:4e:42:14:a1:2a:fb->eth_src
    ct(commit,table=46,zone=NXM_NX_REG12[0..15],nat(src=204.52.24.116))
    nat(src=204.52.24.116)
     -> A clone of the packet is forked to recirculate. The forked
pipeline will be resumed at table 46.
     -> Sets the packet to an untracked state, and clears all the
conntrack fields.

Final flow: 
recirc_id=0x13b5c,eth,tcp,reg10=0x41,reg11=0x4cc,reg12=0x383,reg14=0x1,reg15=0x2,metadata=0x13,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=00:00:5e:00:01:ff,nw_src=172.27.18.244,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=31,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn
Megaflow: 
recirc_id=0x13b5c,ct_state=-rpl+trk,eth,ip,in_port=7753,dl_src=4e:42:14:a1:2a:fb,nw_src=172.27.18.244,nw_frag=no
Datapath actions: ct(commit,zone=899,nat(src=204.52.24.116)),recirc(0x25f9b)

===============================================================================
recirc(0x25f9b) - resume conntrack with default ct_state=trk|new (use
--ct-next to customize)
Replacing src/dst IP/ports to simulate NAT:
 Initial flow: nw_src=172.27.18.244,tp_src=52776,nw_dst=104.18.3.35,tp_dst=443
 Modified flow: nw_src=204.52.24.116,tp_src=52776,nw_dst=104.18.3.35,tp_dst=443
===============================================================================

Flow: 
recirc_id=0x25f9b,ct_state=new|trk,ct_zone=899,eth,tcp,reg10=0x41,reg11=0x4cc,reg12=0x383,reg14=0x1,reg15=0x2,metadata=0x13,in_port=7753,vlan_tci=0x0000,dl_src=4e:42:14:a1:2a:fb,dl_dst=00:00:5e:00:01:ff,nw_src=204.52.24.116,nw_dst=104.18.3.35,nw_tos=0,nw_ecn=0,nw_ttl=31,nw_frag=no,tp_src=52776,tp_dst=443,tcp_flags=syn

bridge("br-int")
----------------
    thaw
        Resuming from table 46
46. metadata=0x13, priority 0, cookie 0x3800cb88
    resubmit(,47)
47. metadata=0x13, priority 0, cookie 0xc2575be2
    resubmit(,48)
48. reg15=0x2,metadata=0x13, priority 100, cookie 0xaf19a22a
    resubmit(,64)
64. reg10=0x1/0x1,reg15=0x2,metadata=0x13, priority 100, cookie 0x407086d0
    push:NXM_OF_IN_PORT[]
    set_field:ANY->in_port
    resubmit(,65)
    65. reg15=0x2,metadata=0x13, priority 100, cookie 0x407086d0
            
clone(ct_clear,set_field:0->reg11,set_field:0->reg12,set_field:0->reg13,set_field:0x2c2->reg11,set_field:0x327->reg12,set_field:0x1->metadata,set_field:0xa->reg14,set_field:0->reg10,set_field:0->reg15,set_field:0->reg0,set_field:0->reg1,set_field:0->reg2,set_field:0->reg3,set_field:0->reg4,set_field:0->reg5,set_field:0->reg6,set_field:0->reg7,set_field:0->reg8,set_field:0->reg9,resubmit(,8))
            ct_clear
            set_field:0->reg11
            set_field:0->reg12
            set_field:0->reg13
            set_field:0x2c2->reg11
            set_field:0x327->reg12
            set_field:0x1->metadata
            set_field:0xa->reg14
            set_field:0->reg10
            set_field:0->reg15
            set_field:0->reg0
            set_field:0->reg1
            set_field:0->reg2
            set_field:0->reg3
            set_field:0->reg4
            set_field:0->reg5
            set_field:0->reg6
            set_field:0->reg7
            set_field:0->reg8
            set_field:0->reg9
            resubmit(,8)
         8. metadata=0x1, priority 50, cookie 0x1645d3f2
            set_field:0/0x1000->reg10
            resubmit(,73)
            73. No match.
                    drop
            move:NXM_NX_REG10[12]->NXM_NX_XXREG0[111]
             -> NXM_NX_XXREG0[111] is now 0
            resubmit(,9)
         9. metadata=0x1, priority 0, cookie 0xcc4fd106
            resubmit(,10)
        10. metadata=0x1, priority 0, cookie 0x9e10ad0e
            resubmit(,11)
        11. metadata=0x1, priority 0, cookie 0x557f3249
            resubmit(,12)
        12. metadata=0x1, priority 0, cookie 0x915c56b1
            resubmit(,13)
        13. ip,reg14=0xa,metadata=0x1, priority 110, cookie 0xccdcd3e1
            resubmit(,14)
        14. metadata=0x1, priority 0, cookie 0x134ce32f
            resubmit(,15)
        15. metadata=0x1, priority 65535, cookie 0x49627e5f
            resubmit(,16)
        16. metadata=0x1, priority 65535, cookie 0xc947843d
            resubmit(,17)
        17. metadata=0x1, priority 0, cookie 0xd2fb4d2
            resubmit(,18)
        18. metadata=0x1, priority 0, cookie 0x62454929
            resubmit(,19)
        19. metadata=0x1, priority 0, cookie 0x3bb47080
            resubmit(,20)
        20. metadata=0x1, priority 0, cookie 0x73face9d
            resubmit(,21)
        21. metadata=0x1, priority 0, cookie 0x8e46634d
            resubmit(,22)
        22. metadata=0x1, priority 0, cookie 0xbddac461
            resubmit(,23)
        23. metadata=0x1, priority 0, cookie 0x9a32c0de
            resubmit(,24)
        24. metadata=0x1, priority 0, cookie 0x79b1c074
            resubmit(,25)
        25. metadata=0x1, priority 0, cookie 0xc02374d3
            resubmit(,26)
        26. metadata=0x1, priority 0, cookie 0x218dc750
            resubmit(,27)
        27. metadata=0x1, priority 0, cookie 0x8db4eebc
            resubmit(,28)
        28. metadata=0x1, priority 0, cookie 0x6deecbbe
            resubmit(,29)
        29. metadata=0x1, priority 0, cookie 0x34e5fac7
            resubmit(,30)
        30. metadata=0x1, priority 0, cookie 0xac3f53bd
            resubmit(,31)
        31. metadata=0x1, priority 0, cookie 0x54000bd5
            resubmit(,32)
        32. metadata=0x1, priority 0, cookie 0x29ab49f3
            resubmit(,33)
        33. metadata=0x1, priority 0, cookie 0xae6aefcb
            resubmit(,34)
        34. metadata=0x1, priority 0, cookie 0x632dc93b
            resubmit(,35)
        35. metadata=0x1, priority 0, cookie 0x9961115c
            set_field:0->reg15
            resubmit(,71)
            71. No match.
                    drop
            resubmit(,36)
        36. reg15=0,metadata=0x1, priority 50, cookie 0x62255993
            set_field:0x8001->reg15
            resubmit(,37)
        37. priority 0
            resubmit(,39)
        39. priority 0
            resubmit(,40)
        40. reg15=0x8001,metadata=0x1, priority 100, cookie 0x11699429
            set_field:0x14->reg13
            set_field:0x1->reg15
            resubmit(,41)
            41. priority 0
                    set_field:0->reg0
                    set_field:0->reg1
                    set_field:0->reg2
                    set_field:0->reg3
                    set_field:0->reg4
                    set_field:0->reg5
                    set_field:0->reg6
                    set_field:0->reg7
                    set_field:0->reg8
                    set_field:0->reg9
                    resubmit(,42)
                42. metadata=0x1, priority 0, cookie 0x9ad1480d
                    resubmit(,43)
                43. ip,reg15=0x1,metadata=0x1, priority 110, cookie 0xca4977d3
                    ct_clear
                    resubmit(,44)
                44. metadata=0x1, priority 0, cookie 0xa1ddb4f6
                    resubmit(,45)
                45. metadata=0x1, priority 65535, cookie 0x91b4350e
                    resubmit(,46)
                46. metadata=0x1, priority 65535, cookie 0xfc9c351d
                    resubmit(,47)
                47. metadata=0x1, priority 0, cookie 0xb984696e
                    resubmit(,48)
                48. metadata=0x1, priority 0, cookie 0xc4f6a97f
                    resubmit(,49)
                49. metadata=0x1, priority 0, cookie 0x8ebb0c71
                    resubmit(,50)
                50. metadata=0x1, priority 0, cookie 0x61e385f4
                    resubmit(,51)
                51. metadata=0x1, priority 0, cookie 0x4c722ce1
                    set_field:0/0x1000->reg10
                    resubmit(,75)
                    75. No match.
                            drop
                    move:NXM_NX_REG10[12]->NXM_NX_XXREG0[111]
                     -> NXM_NX_XXREG0[111] is now 0
                    resubmit(,52)
                52. metadata=0x1, priority 0, cookie 0x3c01b89d
                    resubmit(,64)
                64. priority 0
                    resubmit(,65)
                65. reg15=0x1,metadata=0x1, priority 100, cookie 0x4581da82
                    push_vlan:0x8100
                    set_field:4216->vlan_vid
                    output:7754

                    bridge("br-provider")
                    ---------------------
                         0. priority 0
                            NORMAL
                             -> forwarding to learned port
                    pop_vlan
            set_field:0x8001->reg15
    pop:NXM_OF_IN_PORT[]
     -> NXM_OF_IN_PORT[] is now 7753

Final flow: unchanged
Megaflow: 
recirc_id=0x25f9b,ct_state=+new-est-rel-rpl-inv+trk,ct_mark=0/0x1,eth,ip,in_port=7753,dl_src=4e:42:14:a1:2a:fb,dl_dst=00:00:5e:00:01:ff,nw_dst=0.0.0.0/1,nw_frag=no
Datapath actions: ct_clear,push_vlan(vid=120,pcp=0),5

On Wed, 17 Apr 2024 at 17:32, Gavin McKee <gavmcke...@googlemail.com> wrote:
>
> That information is all in the email
>
> The openflow trace is showing that the pipeline is fine . This is why I’m 
> worried about a deeper issue with the kernal / openvswitch kernal module / 
> connection tracking
>
>
>
> On Wed, Apr 17, 2024 at 16:33 Flavio Leitner <f...@sysclose.org> wrote:
>>
>> On Wed, 17 Apr 2024 12:26:27 -0700
>> Gavin McKee <gavmcke...@googlemail.com> wrote:
>>
>> > Hi Flavio,
>> >
>> > I had to restart the Open vSwitch across 16 machines to resolve the
>> > issue for a customer .  I think it will occur again and when it does
>> > I'll use that command to gather the tc information.
>> >
>> > Until then I think I have found why the issue is occurring .
>> >
>> > Take a look at the output below (this is a packet capture from the
>> > physical interface on the compute node , so traffic that has gone
>> > through the OVS Openflow pipeline) - we make a 3 way handshake with R2
>> > , and establish the connection.  A packet goes missing - TLS
>> > handshake, it then appears that it hasn't gone through NAT as it's
>> > using the Private IP of the VM  .
>>
>>
>> If that is the case, you might be able to see if the data path
>> is matching correctly and the actions are using NAT with
>> ovs-appctl ofproto/trace.
>>
>> fbl
>>
>>
>> >
>> > Take a look at frame 14
>> >
>> > No.     Time               Source                Destination
>> > Protocol Length Info
>> >          Delta
>> >      14 09:24:08.064432    172.27.18.244         104.18.2.35
>> > TLSv1    502    Client Hello, Alert (Level: Fatal, Description: Decode
>> > Error)   2.362983
>> >
>> > Frame 14: 502 bytes on wire (4016 bits), 502 bytes captured (4016
>> > bits) Ethernet II, Src: 4e:42:14:a1:2a:fb (4e:42:14:a1:2a:fb), Dst:
>> > IETF-VRRP-VRID_ff (00:00:5e:00:01:ff)
>> > 802.1Q Virtual LAN, PRI: 0, DEI: 0, ID: 120
>> > Internet Protocol Version 4, Src: 172.27.18.244, Dst: 104.18.2.35
>> > Transmission Control Protocol, Src Port: 57394, Dst Port: 443, Seq: 1,
>> > Ack: 1, Len: 444
>> > Transport Layer Security
>> >     TLSv1 Record Layer: Handshake Protocol: Client Hello
>> >         Content Type: Handshake (22)
>> >         Version: TLS 1.0 (0x0301)
>> >         Length: 432
>> >         Handshake Protocol: Client Hello
>> >     TLSv1 Record Layer: Alert (Level: Fatal, Description: Decode
>> > Error) Content Type: Alert (21)
>> >         Version: TLS 1.0 (0x0301)
>> >         Length: 2
>> >         Alert Message
>> >             Level: Fatal (2)
>> >             Description: Decode Error (50)
>> >
>> >
>> >
>> > ------------------------------------------------------------------------------------------------------------
>> >
>> > On Wed, 17 Apr 2024 at 11:28, Flavio Leitner <f...@sysclose.org> wrote:
>> > >
>> > >
>> > > Hi Gavin,
>> > >
>> > > It would be helpful if you can provide some TC dumps from the
>> > > "good" state to the "bad" state to see how it was and what changes.
>> > > Something like:
>> > >
>> > > # tc -s filter show dev enp148s0f0_1 ingress
>> > >
>> > > I haven't checked the attached files, but one suggestion is to
>> > > check if this is not a csum issue.
>> > >
>> > > Thanks,
>> > > fbl
>> > >
>> > >
>> > > On Tue, 16 Apr 2024 13:17:10 -0700
>> > > Gavin McKee via discuss <ovs-discuss@openvswitch.org> wrote:
>> > >
>> > > > Adding information relating to the Open VSwitch kernal module
>> > > > @Ilya Maximets @Numan Siddique  Can either of you help out here?
>> > > >
>> > > >
>> > > > modinfo openvswitch
>> > > > filename:
>> > > > /lib/modules/5.14.0-362.8.1.el9_3.x86_64/kernel/net/openvswitch/openvswitch.ko.xz
>> > > > alias:          net-pf-16-proto-16-family-ovs_ct_limit
>> > > > alias:          net-pf-16-proto-16-family-ovs_meter
>> > > > alias:          net-pf-16-proto-16-family-ovs_packet
>> > > > alias:          net-pf-16-proto-16-family-ovs_flow
>> > > > alias:          net-pf-16-proto-16-family-ovs_vport
>> > > > alias:          net-pf-16-proto-16-family-ovs_datapath
>> > > > license:        GPL
>> > > > description:    Open vSwitch switching datapath
>> > > > rhelversion:    9.3
>> > > > srcversion:     8A2159D727C8BADC82261B8
>> > > > depends:        nf_conntrack,nf_conncount,libcrc32c,nf_nat
>> > > > retpoline:      Y
>> > > > intree:         Y
>> > > > name:           openvswitch
>> > > > vermagic:       5.14.0-362.8.1.el9_3.x86_64 SMP preempt mod_unload
>> > > > modversions sig_id:         PKCS#7
>> > > > signer:         Rocky kernel signing key
>> > > > sig_key:
>> > > > 17:CA:DE:1F:EC:D1:59:2D:9F:52:34:C6:7C:09:06:81:3D:74:7C:F7
>> > > > sig_hashalgo:   sha256 signature:
>> > > > 67:31:56:70:86:DB:57:69:8D:4A:9B:A7:ED:17:F3:67:65:98:97:08:
>> > > > 1F:FB:4D:F8:A8:2D:7C:A7:7D:3A:57:85:CA:67:9D:82:72:EB:54:14:
>> > > > F2:BB:40:78:AD:85:56:2D:EF:D5:00:95:38:A4:86:9F:5F:29:1A:81:
>> > > > 32:94:B4:87:41:94:A0:3E:71:A5:97:44:2E:42:DD:F7:42:6B:69:94:
>> > > > E3:AB:6E:E5:4F:C9:60:57:70:07:5F:CA:C7:83:7A:2F:C7:81:62:FF:
>> > > > 53:AF:AC:2B:06:D8:08:D3:1D:A7:F0:43:10:98:DE:B1:62:AE:89:A5:
>> > > > FE:EF:74:09:0F:2D:0F:D9:73:A5:59:75:D0:87:1E:EA:3A:40:86:1E:
>> > > > 76:E5:E7:3B:59:2E:3A:7E:65:F3:92:A1:B4:84:48:3F:43:A0:D7:1C:
>> > > > 21:29:E0:B6:D1:10:36:15:88:43:6A:11:8F:55:EE:1B:F9:53:3B:86:
>> > > > EF:81:71:17:81:08:EC:53:30:D6:69:8E:13:11:D5:DF:15:75:88:50:
>> > > > 69:19:51:3B:41:6B:6F:E0:7A:30:33:32:E6:60:18:02:A6:0C:63:9B:
>> > > > C5:D7:2F:6A:D0:BA:45:03:19:0E:21:E8:18:FB:E8:D1:C1:33:05:36:
>> > > > 1F:9B:0F:29:3F:05:51:7A:30:86:88:B7:C7:44:2E:2B:50:F9:EF:4F:
>> > > > D4:70:EA:1B:33:E2:F0:E3:E2:88:00:E5:BF:06:E2:D4:B7:81:EE:6E:
>> > > > 89:02:18:65:8B:1C:84:42:2F:89:14:63:1D:51:70:37:42:C5:68:DD:
>> > > > 4D:12:7B:07:33:2B:C6:BC:8F:7F:23:D7:58:DF:47:AC:DE:08:67:FE:
>> > > > CB:E8:E6:4D:95:2F:6B:F5:07:4D:32:92:80:0A:7C:D1:B6:81:EE:AB:
>> > > > 26:C3:C6:22:77:00:5E:64:DE:96:0E:9F:A4:A0:F0:45:9F:19:73:EB:
>> > > > CC:60:AE:E9:63:E2:6D:2E:BA:65:9B:BD:04:CC:13:C2:55:88:05:03:
>> > > > 1B:30:18:8B
>> > > >
>> > > > On Tue, 16 Apr 2024 at 11:12, Gavin McKee
>> > > > <gavmcke...@googlemail.com> wrote:
>> > > > >
>> > > > > Hi,
>> > > > >
>> > > > > I need some help with strange OVS behaviours.
>> > > > >
>> > > > > ovs-vsctl (Open vSwitch) 3.2.2
>> > > > > ovn-controller 23.09.1
>> > > > > Open vSwitch Library 3.2.2
>> > > > >
>> > > > > TLDR: We need to restart Open VSwitch in order for TLS traffic
>> > > > > to work between a VM and Cloudflare R2.  After restarting Open
>> > > > > VSwitch the TLS connection works fine.
>> > > > > (see attached pcap tls-error.txt)
>> > > > >
>> > > > > See the attached openflow traces - they show a flow trace from
>> > > > > Open Vswitch.
>> > > > >
>> > > > > Also there is a retis trace (retis tool discussed at Open
>> > > > > VSwitch conference 2023).
>> > > > >
>> > > > > Note the drop (TC_INGRESS) in this file
>> > > > >   + 1702601116185568 [swapper/140] 0 [tp] skb:kfree_skb
>> > > > > #60c81b6b91e2cff284fb3a3d65800 (skb 18386033671255367680) n 3
>> > > > > drop (TC_INGRESS)
>> > > > >     if 21 (enp148s0f0_1) rxif 21 172.27.18.244.57394 >
>> > > > > 104.18.2.35.443 ttl 63 tos 0x0 id 26162 off 0 [DF] len 477 proto
>> > > > > TCP (6) flags [P.] seq 792060930:792061367 ack 951229219 win 11
>> > > > >
>> > > > > Again , once I restart Open vSwitch the problem goes away for a
>> > > > > time and comes back sometime later (not sure what that time
>> > > > > frame is but its a recurring issue.)
>> > > > _______________________________________________
>> > > > discuss mailing list
>> > > > disc...@openvswitch.org
>> > > > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
>> > >
>> > >
>> > >
>> > > --
>> > > fbl
>>
>>
>>
>> --
>> fbl
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