I had a curl script and a program that sends messages to gmail that includes attachments. Sometime in June, the curl script started reporting an error:
Trying <ip address>:443...
Connected to api.pushover.net (<ip address>) port 443 (#0)
schannel: disabled automatic use of client certificate
schannel: ALPN, offering http/1.1
schannel: ALPN, server accepted to use http/1.1
POST /1/messages.json HTTP/1.1
Content-Type: multipart/form-data; boundary=------------------------c14a16104b6bac19
schannel: Curl_read_plain returned CURLE_RECV_ERROR
Closing connection 0
schannel: shutting down SSL/TLS connection with api.pushover.net port 443
Send failure: Connection was reset
schannel: failed to send close msg: Failed sending data to the peer (bytes written: -1)
The send via gmail is getting: Error with Gmail Api; 500 Unknown exception (server no response). (12)
Only seems to happen if I am including the attachment.
I'm grasping at straws here because I don't know what else could have changed to break this.
Solved! Go to Correct Answer
No, however, there was a firmware update a few weeks before June.
If you go to the Firewall logging, do you see any dropped or blocked events?
I see this after I try the curl command to send an attachment:
[FW] IPTABLES [Pkt_Illegal] IN=eth4 OUT= MAC=********
src=**.**.***.** DST=**.**.***.*** LEN=40 TOS=0x00 PREC=0x00 TTL=236 ID=0 DF PROTO=TCP SPT=443 DPT=47642 WINDOW=0 RES=0x00 RST URGP=0 MARK=0x8000000
That's difficult to troubleshoot.
iptables won't provide more logging than that, unless someone from engineering to SSH into your router to adjust the log level to verbose/debug.
Are you doing IP fragmentation on curl?
Not that I'm aware of. Like I said, some router configuration change was the last thing I could think of that would cause both curl and the gmail send stop sending attachments.