Post by Dennis FergusonIt looks to me like the packet that isn't being ack'd may actually be
going in the other direction, from the server to the client. It is
06:30:36.457041 IP (tos 0x0, ttl 50, id 27541, offset 0, flags [DF], proto TCP (6), length 61)
ftp.solnet.ch.ftp > ip-176-199-201-17.hsi06.unitymediagroup.de.65151: Flags [P.], cksum 0xe404 (correct), seq 1296:1305, ack 43, win 1040, options [nop,nop,TS val 3171079293 ecr 1], length 9
0x0010: b0c7 c911 0015 fe7f e09e abf3 1996 ee58 ...............X
0x0020: 8018 0410 e404 0000 0101 080a bd02 d47d ...............}
0x0030: 0000 0001 3231 3120 456e 640d 0a ....211.End..
Ok, I see this packet show up in a tcpdump on the awge interface, so
should be able to trace it further. This is (currently) all software
checksums, and since the packet made it to the bpf_mtap, it can't be
hardware. I don't see an ACK to this packet in the local trace, so I guess
it realy is the receiving side somewhere further up in the stack that
drops it.
netstat -s below...
I wonder where the PMTUD blackhole comes from (MTU on awge is 1500,
just like on the other machines here that can do the test without
adding a PMTUD blackhole).
Martin
icmp:
0 calls to icmp_error
0 errors not generated because old message was icmp
Output histogram:
echoreply: 1
0 messages with bad code fields
0 messages < minimum length
0 bad checksums
0 messages with bad length
0 multicast echo requests ignored
0 multicast timestamp requests ignored
Input histogram:
echo: 1
photuris: 1096454688104512
1 message response generated
0 path MTU changes
igmp:
1 message received
0 messages received with too few bytes
0 messages received with bad checksum
1 membership query received
0 membership queries received with invalid field(s)
0 membership reports received
0 membership reports received with invalid field(s)
0 membership reports received for groups to which we belong
0 membership reports sent
tcp:
250 packets sent
170 data packets (33646 bytes)
0 data packets (0 bytes) retransmitted
70 ack-only packets (197 delayed)
0 URG only packets
0 window probe packets
1 window update packet
9 control packets
0 send attempts resulted in self-quench
284 packets received
163 acks (for 33649 bytes)
1 duplicate ack
0 acks for unsent data
250 packets (29579 bytes) received in-sequence
0 completely duplicate packets (0 bytes)
0 old duplicate packets
0 packets with some dup. data (0 bytes duped)
0 out-of-order packets (0 bytes)
0 packets (0 bytes) of data after window
0 window probes
2 window update packets
0 packets received after close
9 discarded for bad checksums
0 discarded for bad header offset fields
0 discarded because packet too short
2 connection requests
2 connection accepts
4 connections established (including accepts)
7 connections closed (including 0 drops)
0 embryonic connections dropped
0 delayed frees of tcpcb
165 segments updated rtt (of 161 attempts)
5 retransmit timeouts
0 connections dropped by rexmit timeout
0 persist timeouts (resulting in 0 dropped connections)
0 keepalive timeouts
0 keepalive probes sent
0 connections dropped by keepalive
0 correct ACK header predictions
100 correct data packet header predictions
4 PCB hash misses
0 dropped due to no socket
0 connections drained due to memory shortage
1 PMTUD blackhole detected
0 bad connection attempts
2 SYN cache entries added
0 hash collisions
2 completed
0 aborted (no space to build PCB)
0 timed out
0 dropped due to overflow
0 dropped due to bucket overflow
0 dropped due to RST
0 dropped due to ICMP unreachable
2 delayed free of SYN cache entries
0 SYN,ACKs retransmitted
0 duplicate SYNs received for entries already in the cache
0 SYNs dropped (no route or no space)
0 packets with bad signature
0 packets with good signature
0 successful ECN handshakes
0 packets with ECN CE bit
0 packets ECN ECT(0) bit
udp:
16 datagrams received
0 with incomplete header
0 with bad data length field
0 with bad checksum
0 dropped due to no socket
2 broadcast/multicast datagrams dropped due to no socket
0 dropped due to full socket buffers
14 delivered
5 PCB hash misses
14 datagrams output
ip:
303 total packets received
0 bad header checksums
0 with size smaller than minimum
0 with data size < data length
0 with length > max ip packet size
0 with header length < data size
0 with data length < header length
0 with bad options
0 with incorrect version number
0 fragments received
0 fragments dropped (dup or out of space)
0 fragments dropped (out of ipqent)
0 malformed fragments dropped
0 fragments dropped after timeout
0 packets reassembled ok
302 packets for this host
0 packets for unknown/unsupported protocol
0 packets forwarded (0 packets fast forwarded)
1 packet not forwardable
0 redirects sent
0 packets no matching gif found
265 packets sent from this host
0 packets sent with fabricated ip header
0 output packets dropped due to no bufs, etc.
0 output packets discarded due to no route
0 output datagrams fragmented
0 fragments created
0 datagrams that can't be fragmented
0 datagrams with bad address in header
ip6:
6 total packets received
0 with size smaller than minimum
0 with data size < data length
0 with bad options
0 with incorrect version number
0 fragments received
0 fragments dropped (dup or out of space)
0 fragments dropped after timeout
0 fragments that exceeded limit
0 packets reassembled ok
6 packets for this host
0 packets forwarded
0 packets fast forwarded
0 fast forward flows
0 packets not forwardable
0 redirects sent
15 packets sent from this host
0 packets sent with fabricated ip header
0 output packets dropped due to no bufs, etc.
0 output packets discarded due to no route
0 output datagrams fragmented
0 fragments created
0 datagrams that can't be fragmented
0 packets that violated scope rules
0 multicast packets which we don't join
Input packet histogram:
UDP: 3
ICMP6: 3
Mbuf statistics:
0 one mbufs
6 one ext mbufs
0 two or more ext mbufs
0 packets whose headers are not continuous
0 tunneling packets that can't find gif
0 packets discarded due to too many headers
0 failures of source address selection
3 forward cache hit
2 forward cache miss
icmp6:
0 calls to icmp6_error
0 errors not generated because old message was icmp6 or so
0 errors not generated because of rate limitation
Output packet histogram:
multicast listener report: 8
router solicitation: 1
neighbor solicitation: 3
0 messages with bad code fields
0 messages < minimum length
0 bad checksums
0 messages with bad length
Input packet histogram:
router advertisement: 1
neighbor advertisement: 2
Histogram of error messages to be generated:
0 no route
0 administratively prohibited
0 beyond scope
0 address unreachable
0 port unreachable
0 packet too big
0 time exceed transit
0 time exceed reassembly
0 erroneous header field
0 unrecognized next header
0 unrecognized option
0 redirect
0 unknown
0 message responses generated
0 messages with too many ND options
0 messages with bad ND options
0 bad neighbor solicitation messages
0 bad neighbor advertisement messages
0 bad router solicitation messages
0 bad router advertisement messages
0 router advertisement routes dropped
0 bad redirect messages
0 path MTU changes
tcp6:
250 packets sent
170 data packets (33646 bytes)
0 data packets (0 bytes) retransmitted
70 ack-only packets (197 delayed)
0 URG only packets
0 window probe packets
1 window update packet
9 control packets
0 send attempts resulted in self-quench
284 packets received
163 acks (for 33649 bytes)
1 duplicate ack
0 acks for unsent data
250 packets (29579 bytes) received in-sequence
0 completely duplicate packets (0 bytes)
0 old duplicate packets
0 packets with some dup. data (0 bytes duped)
0 out-of-order packets (0 bytes)
0 packets (0 bytes) of data after window
0 window probes
2 window update packets
0 packets received after close
9 discarded for bad checksums
0 discarded for bad header offset fields
0 discarded because packet too short
2 connection requests
2 connection accepts
4 connections established (including accepts)
7 connections closed (including 0 drops)
0 embryonic connections dropped
0 delayed frees of tcpcb
165 segments updated rtt (of 161 attempts)
5 retransmit timeouts
0 connections dropped by rexmit timeout
0 persist timeouts (resulting in 0 dropped connections)
0 keepalive timeouts
0 keepalive probes sent
0 connections dropped by keepalive
0 correct ACK header predictions
100 correct data packet header predictions
4 PCB hash misses
0 dropped due to no socket
0 connections drained due to memory shortage
1 PMTUD blackhole detected
0 bad connection attempts
2 SYN cache entries added
0 hash collisions
2 completed
0 aborted (no space to build PCB)
0 timed out
0 dropped due to overflow
0 dropped due to bucket overflow
0 dropped due to RST
0 dropped due to ICMP unreachable
2 delayed free of SYN cache entries
0 SYN,ACKs retransmitted
0 duplicate SYNs received for entries already in the cache
0 SYNs dropped (no route or no space)
0 packets with bad signature
0 packets with good signature
0 successful ECN handshakes
0 packets with ECN CE bit
0 packets ECN ECT(0) bit
udp6:
3 datagrams received
0 with incomplete header
0 with bad data length field
0 with bad checksum
0 with no checksum
0 dropped due to no socket
0 multicast datagrams dropped due to no socket
0 dropped due to full socket buffers
3 delivered
3 datagrams output
pim6:
0 messages received
0 messages received with too few bytes
0 messages received with bad checksum
0 messages received with bad version
0 registers received
0 bad registers received
0 registers sent
rip6:
0 messages received
0 checksum calculations on inbound
0 messages with bad checksum
0 messages dropped due to no socket
0 multicast messages dropped due to no socket
0 messages dropped due to full socket buffers
0 delivered
0 datagrams output
arp:
4 packets sent
0 reply packets
4 request packets
13 packets received
3 reply packets
10 valid request packets
10 broadcast/multicast packets
0 packets with unknown protocol type
0 packets with bad (short) length
0 packets with null target IP address
0 packets with null source IP address
0 could not be mapped to an interface
0 packets sourced from a local hardware address
0 packets with a broadcast source hardware address
0 duplicates for a local IP address
0 attempts to overwrite a static entry
0 packets received on wrong interface
0 entrys overwritten
0 changes in hardware address length
3 packets deferred pending ARP resolution
3 sent
0 dropped
0 failures to allocate llinfo
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