![]() ![]() Turns out, the damn C program had absolutely no clue about TCP reassembly. All of a sudden it would choke and start spitting garbage out, and only restarting everything made it go away. Our end had a C program consuming those TCP packets and pushing every transaction received to a POSIX queue, to be consumed by COBOL programs. Wrote a LUA decoder to a proprietary protocol (in EBCDIC, too, since why would it be easy?), that allowed us to diagnose why a certain system wasn't working well enough (aka either froze completely or actually did random things) during the busiest (and therefore most profitable) periods of time. ![]() One of the many times Wireshark has proven invaluable! During that time frame our file servers were updated and when we cut the traffic back over, the problem cropped up. ![]() It all happened because that offsite traffic hadn't been going through the accelerator for a few weeks while our WAN was being redone. Server never saw that and so always assumed SMB. ![]() Coincidentally this is where the client specified that it could negotiate SMB2. The WAAS was set to accelerate CIFS traffic and to do so was truncating the last 14 bytes of the packet header. I finally figured out what was happening when I realized that the off site traffic was hitting a Cisco wan accelerator box. Only happened at one site and more importantly only happened to people mapping from off site - people physically located where the file server was had no issues. I quickly noticed that I would send a packet telling the server I could do SMB2, but the server would only get that I could do SMB and then the mapping would fail due to a known issue where SMB2 was required when using cnames. Once we narrowed it down, I captured on the client side and on the server. It took a while to get wire shark involved because we didn't initially realize all the people having issues were going mapping to a particular file server. One of the ones I remember best involved people being unable to map drives all of a sudden. ![]()
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