This all-in-one printer can scan to a Windows share. I have a Windows share hosted by Samba on FreeBSD.
Unfortunately, the printer/scanner intermittently (and pretty often) says it can’t find my FreeBSD machine when I–or more importantly my wife tries to scan a document.
I went pretty deep on this and took a packet capture:
| No. | Time | Source | Destination | Protocol | Length | Info |
| 1 | 0.000000 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 37397 > microsoft-ds [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172908768 TSecr=0 |
| 2 | 0.000051 | 192.168.1.8 | 192.168.1.6 | TCP | 74 | microsoft-ds > 37397 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1460 WS=8 SACK_PERM=1 TSval=2914822213 TSecr=172908768 |
| 3 | 0.000311 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37397 > microsoft-ds [ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172908768 TSecr=2914822213 |
| 4 | 0.000371 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | [TCP Window Update] microsoft-ds > 37397 [ACK] Seq=1 Ack=1 Win=131768 Len=0 TSval=2914822214 TSecr=172908768 |
| 5 | 0.001279 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37397 > microsoft-ds [FIN, PSH, ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172908768 TSecr=2914822214 |
| 6 | 0.001299 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37397 [ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914822219 TSecr=172908768 |
| 7 | 0.002105 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 42026 > netbios-ssn [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172908768 TSecr=0 |
| 8 | 0.002119 | 192.168.1.8 | 192.168.1.6 | TCP | 54 | netbios-ssn > 42026 [RST, ACK] Seq=1 Ack=1 Win=0 Len=0 |
| 9 | 0.003119 | 192.168.1.6 | 192.168.1.255 | NBNS | 92 | Name query NB SERVER |
| 10 | 0.003465 | 192.168.1.8 | 192.168.1.6 | NBNS | 104 | Name query response NB 192.168.1.8 |
| 11 | 0.004313 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 37032 > microsoft-ds [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172908768 TSecr=0 |
| 12 | 0.004341 | 192.168.1.8 | 192.168.1.6 | TCP | 74 | microsoft-ds > 37032 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1460 WS=8 SACK_PERM=1 TSval=2914321147 TSecr=172908768 |
| 13 | 0.005036 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37032 > microsoft-ds [ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172908768 TSecr=2914321147 |
| 14 | 0.005083 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | [TCP Window Update] microsoft-ds > 37032 [ACK] Seq=1 Ack=1 Win=131768 Len=0 TSval=2914321151 TSecr=172908768 |
| 15 | 0.005413 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37032 > microsoft-ds [FIN, PSH, ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172908768 TSecr=2914321151 |
| 16 | 0.005433 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37032 [ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914321153 TSecr=172908768 |
| 17 | 0.029184 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37397 [FIN, ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914822358 TSecr=172908768 |
| 18 | 0.029224 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37397 [FIN, ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914822358 TSecr=172908768 |
| 19 | 0.029246 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37032 [FIN, ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914321272 TSecr=172908768 |
| 20 | 0.029260 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 37032 [FIN, ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=2914321272 TSecr=172908768 |
| 21 | 0.093285 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37397 > microsoft-ds [ACK] Seq=2 Ack=2 Win=8687 Len=0 TSval=172908785 TSecr=2914822358 |
| 22 | 0.093670 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | [TCP Dup ACK 21#1] 37397 > microsoft-ds [ACK] Seq=2 Ack=2 Win=8687 Len=0 TSval=172908785 TSecr=2914822358 |
| 23 | 0.093700 | 192.168.1.8 | 192.168.1.6 | TCP | 54 | microsoft-ds > 37397 [RST] Seq=2 Win=0 Len=0 |
| 24 | 0.094072 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 37032 > microsoft-ds [ACK] Seq=2 Ack=2 Win=8687 Len=0 TSval=172908785 TSecr=2914321272 |
| 25 | 0.094478 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | [TCP Dup ACK 24#1] 37032 > microsoft-ds [ACK] Seq=2 Ack=2 Win=8687 Len=0 TSval=172908785 TSecr=2914321272 |
| 26 | 0.094495 | 192.168.1.8 | 192.168.1.6 | TCP | 54 | microsoft-ds > 37032 [RST] Seq=2 Win=0 Len=0 |
| 27 | 0.095211 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 41297 > netbios-ssn [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172908785 TSecr=0 |
| 28 | 0.095223 | 192.168.1.8 | 192.168.1.6 | TCP | 54 | netbios-ssn > 41297 [RST, ACK] Seq=1 Ack=1 Win=0 Len=0 |
| 29 | 3.723899 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 41299 > microsoft-ds [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172911692 TSecr=0 |
| 30 | 3.723940 | 192.168.1.8 | 192.168.1.6 | TCP | 74 | microsoft-ds > 41299 [SYN, ACK] Seq=0 Ack=1 Win=65535 Len=0 MSS=1460 WS=8 SACK_PERM=1 TSval=748713777 TSecr=172911692 |
| 31 | 3.724734 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 41299 > microsoft-ds [ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172911692 TSecr=748713777 |
| 32 | 3.724789 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | [TCP Window Update] microsoft-ds > 41299 [ACK] Seq=1 Ack=1 Win=131768 Len=0 TSval=748713781 TSecr=172911692 |
| 33 | 3.725582 | 192.168.1.6 | 192.168.1.8 | TCP | 66 | 41299 > microsoft-ds [FIN, PSH, ACK] Seq=1 Ack=1 Win=8688 Len=0 TSval=172911692 TSecr=748713781 |
| 34 | 3.725623 | 192.168.1.8 | 192.168.1.6 | TCP | 66 | microsoft-ds > 41299 [ACK] Seq=1 Ack=2 Win=131768 Len=0 TSval=748713786 TSecr=172911692 |
| 35 | 3.726713 | 192.168.1.6 | 192.168.1.8 | TCP | 78 | 34127 > netbios-ssn [SYN] Seq=0 Win=8688 Len=0 MSS=1460 WS=1 SACK_PERM=1 TSval=172911692 TSecr=0 |
| 36 | 3.726749 | 192.168.1.8 | 192.168.1.6 | TCP | 54 | netbios-ssn > 34127 [RST, ACK] Seq=1 Ack=1 Win=0 Len=0 |
| 37 | 3.727577 | 192.168.1.6 | 192.168.1.255 | NBNS | 92 | Name query NB SERVER |
| 38 | 3.728030 | 192.168.1.8 | 192.168.1.6 | NBNS | 104 | Name query response NB 192.168.1.8 |
| 39 | 3.728393 | 192.168.1.8 | 192.168.1.6 | NBNS | 104 | Name query response NB 192.168.1.8 |
| 40 | 3.728788 | 192.168.1.6 | 192.168.1.8 | ICMP | 70 | Destination unreachable (Port unreachable) |
The HP printer/scanner for some reason disconnects the TCP session right after it connects (right after the 3-way handshake) with a FIN/PSH/ACK. It starts out trying to connect on port 445 and then disconnects–as far as I can tell for no reason. My guess is that a stale thread exists that doesn’t get cleaned up, and that thread is handling the new connection (when it shouldn’t be). The thread doesn’t know what to do with it, so it closes the connection.
I’ve also seen that immediately after this happens, a new connection is attempted on port 139 (which is a legacy SMB port). This connection goes unanswered by FreeBSD because I had a line in smb.conf that says:
smb ports = 445
Which means it only listens on port 445, not the legacy 139. This was done supposedly to get rid of getpeername errors in the logs. I removed this line, and I can’t say that the HP all-in-one scans successfully 100% of the time, but it is certainly more often. My guess is that when the HP attempts both ports 445 and ports 139 (and Samba listens to both), it increases the probability that new thread is created to handle the connection and the error doesn’t occur as often.
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