dndx / phantun

Transforms UDP stream into (fake) TCP streams that can go through Layer 3 & Layer 4 (NAPT) firewalls/NATs.
Apache License 2.0
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Waiting for SYN + ACK timed out #159

Closed Ansen closed 4 months ago

Ansen commented 4 months ago

The server in Shanghai has this problem, but the same configuration is correct on servers in other regions,

It seems that the client cannot receive the SYN + ACK sent by the server. Is it blocked?

THX.

server trace log:

# RUST_LOG=trace phantun_server --local 21080 --remote 127.0.0.1:41111
 INFO  server > Remote address is: 127.0.0.1:41111
 INFO  server > 4 cores available
 DEBUG neli::socket > Message sent:
Nlmsghdr { nl_len: 64, nl_type: Newaddr, nl_flags: NlmFFlags(FlagBuffer(1, PhantomData<neli::consts::nl::NlmF>)), nl_seq: 0, nl_pid: 0, nl_payload: Payload(Ifaddrmsg { ifa_family: Inet6, ifa_prefixlen: 128, ifa_flags: IfaFFlags(FlagBuffer(0, PhantomData<neli::consts::rtnl::IfaF>)), ifa_scope: 0, ifa_index: 14, rtattrs: RtBuffer([Rtattr { rta_len: 20, rta_type: Local, rta_payload: Buffer }, Rtattr { rta_len: 20, rta_type: Address, rta_payload: Buffer }]) }) }
 INFO  server       > Created TUN device tun0
 INFO  server       > Listening on 21080
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Waiting for client ACK timed out
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 TRACE fake_tcp     > Storing connection information into local tuples
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Waiting for client ACK timed out
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Fake TCP connection to (Fake TCP connection from 192.168.201.2:21080 to my_.router.public.ip:10841) closed
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Waiting for client ACK timed out
 INFO  fake_tcp     > Sent SYN + ACK to client
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 TRACE fake_tcp     > Storing connection information into local tuples
 INFO  fake_tcp     > Fake TCP connection to (Fake TCP connection from 192.168.201.2:21080 to my_.router.public.ip:10841) closed
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:10841 }
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Waiting for client ACK timed out
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection
 TRACE fake_tcp     > Storing connection information into local tuples
 INFO  fake_tcp     > Sent SYN + ACK to client
 INFO  fake_tcp     > Waiting for client ACK timed out
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:28677 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:28677 }
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:28677 }
 INFO  fake_tcp     > Fake TCP connection to (Fake TCP connection from 192.168.201.2:21080 to my_.router.public.ip:28677) closed
 TRACE fake_tcp     > Removed cached tuple: AddrTuple { local_addr: 192.168.201.2:21080, remote_addr: my_.router.public.ip:28677 }
 TRACE fake_tcp     > Cache miss, checking the shared tuples table for connection

client trace log:

# RUST_LOG=trace /data/runtime/phantun_client --local 127.0.0.1:12080 --remote remote.host.ip:21080
 INFO  client > Remote address is: remote.host.ip:21080
 INFO  client > 4 cores available
 TRACE mio::poll > registering event source with poller: token=Token(1), interests=READABLE | WRITABLE
 TRACE mio::poll > registering event source with poller: token=Token(2), interests=READABLE | WRITABLE
 TRACE mio::poll > registering event source with poller: token=Token(3), interests=READABLE | WRITABLE
 TRACE mio::poll > registering event source with poller: token=Token(4), interests=READABLE | WRITABLE
 INFO  client    > Created TUN device tun0
 TRACE mio::poll > registering event source with poller: token=Token(5), interests=READABLE | WRITABLE
 INFO  client    > New UDP client from 127.0.0.1:59184
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 INFO  fake_tcp  > Fake TCP connection to (Fake TCP connection from 192.168.200.2:10841 to remote.host.ip:21080) closed
 ERROR client    > Unable to connect to remote remote.host.ip:21080
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:10841, remote_addr: remote.host.ip:21080 }
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:10841, remote_addr: remote.host.ip:21080 }
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:10841, remote_addr: remote.host.ip:21080 }
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:10841, remote_addr: remote.host.ip:21080 }
 INFO  client    > New UDP client from 127.0.0.1:59184
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 INFO  fake_tcp  > Sent SYN to server
 INFO  fake_tcp  > Waiting for SYN + ACK timed out
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:28677, remote_addr: remote.host.ip:21080 }
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:28677, remote_addr: remote.host.ip:21080 }
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:28677, remote_addr: remote.host.ip:21080 }
 INFO  fake_tcp  > Fake TCP connection to (Fake TCP connection from 192.168.200.2:28677 to remote.host.ip:21080) closed
 ERROR client    > Unable to connect to remote remote.host.ip:21080
 TRACE fake_tcp  > Removed cached tuple: AddrTuple { local_addr: 192.168.200.2:28677, remote_addr: remote.host.ip:21080 }
 INFO  client    > New UDP client from 127.0.0.1:59184
 INFO  fake_tcp  > Sent SYN to server

server tcpdump

# tcpdump -i eth0  port 21080 -n   -v
tcpdump: listening on ens160, link-type EN10MB (Ethernet), snapshot length 262144 bytes
09:56:18.153925 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.43719 > remote.host.ip.21080: Flags [S], cksum 0x1a3e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:18.154315 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.43719: Flags [S.], cksum 0x1a2d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:19.154049 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.43719 > remote.host.ip.21080: Flags [S], cksum 0x1a3e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:20.155430 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.43719 > remote.host.ip.21080: Flags [S], cksum 0x1a3e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:20.155752 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.43719: Flags [S.], cksum 0x1a2d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:21.156755 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.43719 > remote.host.ip.21080: Flags [R], cksum 0x4271 (correct), seq 0, win 65535, length 0
09:56:21.157026 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.43719: Flags [R], cksum 0x4271 (correct), seq 0, win 65535, length 0
09:56:23.272934 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.34519 > remote.host.ip.21080: Flags [S], cksum 0x3e2e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:23.273299 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.34519: Flags [S.], cksum 0x3e1d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:24.273327 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.34519 > remote.host.ip.21080: Flags [S], cksum 0x3e2e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:25.274664 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.34519 > remote.host.ip.21080: Flags [S], cksum 0x3e2e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:25.274926 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.34519: Flags [S.], cksum 0x3e1d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:26.275244 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.34519 > remote.host.ip.21080: Flags [R], cksum 0x6661 (correct), seq 0, win 65535, length 0
09:56:26.275509 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.34519: Flags [R], cksum 0x6661 (correct), seq 0, win 65535, length 0
09:56:28.392870 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.14720 > remote.host.ip.21080: Flags [S], cksum 0x8b85 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:28.393196 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.14720: Flags [S.], cksum 0x8b74 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:29.393992 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.14720 > remote.host.ip.21080: Flags [S], cksum 0x8b85 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:29.394274 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.14720: Flags [S.], cksum 0x8b74 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:30.395656 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.14720 > remote.host.ip.21080: Flags [S], cksum 0x8b85 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:30.396007 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.14720: Flags [S.], cksum 0x8b74 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:30.396163 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.14720: Flags [R], cksum 0xb3b8 (correct), seq 0, win 65535, length 0
09:56:31.397246 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.14720 > remote.host.ip.21080: Flags [R], cksum 0xb3b8 (correct), seq 0, win 65535, length 0
09:56:33.513096 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.12885 > remote.host.ip.21080: Flags [S], cksum 0x92b0 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:33.513462 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.12885: Flags [S.], cksum 0x929f (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:34.513375 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.12885 > remote.host.ip.21080: Flags [S], cksum 0x92b0 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:35.514070 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.12885: Flags [S.], cksum 0x929f (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:35.514747 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.12885 > remote.host.ip.21080: Flags [S], cksum 0x92b0 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:36.515192 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.12885 > remote.host.ip.21080: Flags [R], cksum 0xbae3 (correct), seq 0, win 65535, length 0
09:56:36.515600 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.12885: Flags [R], cksum 0xbae3 (correct), seq 0, win 65535, length 0
09:56:38.632727 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.28264 > remote.host.ip.21080: Flags [S], cksum 0x569d (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:38.633068 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.28264: Flags [S.], cksum 0x568c (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:39.634575 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.28264: Flags [S.], cksum 0x568c (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:39.635826 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.28264 > remote.host.ip.21080: Flags [S], cksum 0x569d (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:40.635300 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.28264 > remote.host.ip.21080: Flags [S], cksum 0x569d (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:41.636818 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.28264 > remote.host.ip.21080: Flags [R], cksum 0x7ed0 (correct), seq 0, win 65535, length 0
09:56:41.636829 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.28264: Flags [R], cksum 0x7ed0 (correct), seq 0, win 65535, length 0
09:56:43.752550 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.46853 > remote.host.ip.21080: Flags [S], cksum 0x0e00 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:43.752860 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.46853: Flags [S.], cksum 0x0def (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:44.752631 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.46853 > remote.host.ip.21080: Flags [S], cksum 0x0e00 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:45.754197 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.46853: Flags [S.], cksum 0x0def (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:45.754273 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.46853 > remote.host.ip.21080: Flags [S], cksum 0x0e00 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:46.755447 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.46853 > remote.host.ip.21080: Flags [R], cksum 0x3633 (correct), seq 0, win 65535, length 0
09:56:46.755721 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.46853: Flags [R], cksum 0x3633 (correct), seq 0, win 65535, length 0
09:56:48.873896 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.6696 > remote.host.ip.21080: Flags [S], cksum 0xaadd (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:48.874235 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.6696: Flags [S.], cksum 0xaacc (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:49.873907 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.6696 > remote.host.ip.21080: Flags [S], cksum 0xaadd (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:50.875630 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.6696: Flags [S.], cksum 0xaacc (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:50.875748 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.6696 > remote.host.ip.21080: Flags [S], cksum 0xaadd (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:51.876198 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.6696 > remote.host.ip.21080: Flags [R], cksum 0xd310 (correct), seq 0, win 65535, length 0
09:56:51.876466 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.6696: Flags [R], cksum 0xd310 (correct), seq 0, win 65535, length 0
09:56:53.992254 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.50799 > remote.host.ip.21080: Flags [S], cksum 0xfe95 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:53.992556 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.50799: Flags [S.], cksum 0xfe84 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:54.992817 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.50799 > remote.host.ip.21080: Flags [S], cksum 0xfe95 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:54.993349 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.50799: Flags [S.], cksum 0xfe84 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:55.994261 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.50799 > remote.host.ip.21080: Flags [S], cksum 0xfe95 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:56.995317 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.50799 > remote.host.ip.21080: Flags [R], cksum 0x26c9 (correct), seq 0, win 65535, length 0
09:56:56.995671 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.50799: Flags [R], cksum 0x26c9 (correct), seq 0, win 65535, length 0
09:56:59.111949 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.8593 > remote.host.ip.21080: Flags [S], cksum 0xa374 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:56:59.112233 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.8593: Flags [S.], cksum 0xa363 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:00.112577 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.8593 > remote.host.ip.21080: Flags [S], cksum 0xa374 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:01.113872 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.8593 > remote.host.ip.21080: Flags [S], cksum 0xa374 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:01.114137 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.8593: Flags [S.], cksum 0xa363 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:02.114586 IP (tos 0x0, ttl 53, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.8593 > remote.host.ip.21080: Flags [R], cksum 0xcba7 (correct), seq 0, win 65535, length 0
09:57:02.114952 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.8593: Flags [R], cksum 0xcba7 (correct), seq 0, win 65535, length 0
09:57:04.233183 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.7815 > remote.host.ip.21080: Flags [S], cksum 0xa67e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:04.233524 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.7815: Flags [S.], cksum 0xa66d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:05.234571 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.7815 > remote.host.ip.21080: Flags [S], cksum 0xa67e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:05.234899 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.7815: Flags [S.], cksum 0xa66d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:06.235888 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.7815 > remote.host.ip.21080: Flags [S], cksum 0xa67e (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:06.236187 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.7815: Flags [S.], cksum 0xa66d (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:06.236284 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.7815: Flags [R], cksum 0xceb1 (correct), seq 0, win 65535, length 0
09:57:07.237254 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.7815 > remote.host.ip.21080: Flags [R], cksum 0xceb1 (correct), seq 0, win 65535, length 0
09:57:09.352985 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.49124 > remote.host.ip.21080: Flags [S], cksum 0x0521 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:09.353368 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.49124: Flags [S.], cksum 0x0510 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:10.353191 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.49124 > remote.host.ip.21080: Flags [S], cksum 0x0521 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:11.354130 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    remote.host.ip.21080 > 222.209.232.58.49124: Flags [S.], cksum 0x0510 (correct), seq 0, ack 1, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:11.354647 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 48)
    222.209.232.58.49124 > remote.host.ip.21080: Flags [S], cksum 0x0521 (correct), seq 0, win 65535, options [mss 536,nop,wscale 14], length 0
09:57:12.356038 IP (tos 0x0, ttl 54, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    222.209.232.58.49124 > remote.host.ip.21080: Flags [R], cksum 0x2d54 (correct), seq 0, win 65535, length 0
09:57:12.356056 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    remote.host.ip.21080 > 222.209.232.58.49124: Flags [R], cksum 0x2d54 (correct), seq 0, win 65535, length 0

client tcpdump

# tcpdump -i eth0  port 21080 -n -v
tcpdump: listening on eth0, link-type EN10MB (Ethernet), snapshot length 262144 bytes
09:56:34.524592 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.12885 > remote.host.ip.21080: Flags [S], cksum 0xe531 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:35.525984 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.12885 > remote.host.ip.21080: Flags [S], cksum 0xe531 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:36.526242 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.12885 > remote.host.ip.21080: Flags [R], cksum 0xf944 (correct), seq 0, win 65535, length 0
09:56:38.643970 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.28264 > remote.host.ip.21080: Flags [S], cksum 0xa91e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:39.645264 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.28264 > remote.host.ip.21080: Flags [S], cksum 0xa91e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:40.646685 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.28264 > remote.host.ip.21080: Flags [S], cksum 0xa91e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:41.648203 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.28264 > remote.host.ip.21080: Flags [R], cksum 0xbd31 (correct), seq 0, win 65535, length 0
09:56:43.763928 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.46853 > remote.host.ip.21080: Flags [S], cksum 0x6081 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:44.764274 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.46853 > remote.host.ip.21080: Flags [S], cksum 0x6081 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:45.765548 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.46853 > remote.host.ip.21080: Flags [S], cksum 0x6081 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:46.766932 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.46853 > remote.host.ip.21080: Flags [R], cksum 0x7494 (correct), seq 0, win 65535, length 0
09:56:48.883863 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.6696 > remote.host.ip.21080: Flags [S], cksum 0xfd5e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:49.884850 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.6696 > remote.host.ip.21080: Flags [S], cksum 0xfd5e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:50.885305 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.6696 > remote.host.ip.21080: Flags [S], cksum 0xfd5e (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:51.886670 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.6696 > remote.host.ip.21080: Flags [R], cksum 0x1172 (correct), seq 0, win 65535, length 0
09:56:54.003863 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.50799 > remote.host.ip.21080: Flags [S], cksum 0x5117 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:55.004442 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.50799 > remote.host.ip.21080: Flags [S], cksum 0x5117 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:56.005761 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.50799 > remote.host.ip.21080: Flags [S], cksum 0x5117 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:56:57.007196 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.50799 > remote.host.ip.21080: Flags [R], cksum 0x652a (correct), seq 0, win 65535, length 0
09:56:59.123952 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.8593 > remote.host.ip.21080: Flags [S], cksum 0xf5f5 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:00.124431 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.8593 > remote.host.ip.21080: Flags [S], cksum 0xf5f5 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:01.125895 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.8593 > remote.host.ip.21080: Flags [S], cksum 0xf5f5 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:02.126390 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.8593 > remote.host.ip.21080: Flags [R], cksum 0x0a09 (correct), seq 0, win 65535, length 0
09:57:04.243974 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.7815 > remote.host.ip.21080: Flags [S], cksum 0xf8ff (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:05.245419 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.7815 > remote.host.ip.21080: Flags [S], cksum 0xf8ff (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:06.246715 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.7815 > remote.host.ip.21080: Flags [S], cksum 0xf8ff (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:07.248257 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.7815 > remote.host.ip.21080: Flags [R], cksum 0x0d13 (correct), seq 0, win 65535, length 0
09:57:09.363958 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.49124 > remote.host.ip.21080: Flags [S], cksum 0x57a2 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:10.364236 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.49124 > remote.host.ip.21080: Flags [S], cksum 0x57a2 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:11.365706 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.49124 > remote.host.ip.21080: Flags [S], cksum 0x57a2 (correct), seq 0, win 65535, options [nop,wscale 14], length 0
09:57:12.367220 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 40)
    192.168.200.2.49124 > remote.host.ip.21080: Flags [R], cksum 0x6bb5 (correct), seq 0, win 65535, length 0
09:57:14.483998 IP (tos 0x0, ttl 63, id 0, offset 0, flags [DF], proto TCP (6), length 44)
    192.168.200.2.24338 > remote.host.ip.21080: Flags [S], cksum 0xb874 (correct), seq 0, win 65535, options [nop,wscale 14], length 0