ncat: nsock_loop error 10038 #978
Description
Synopsis:
Ncat 7.60 on Windows is unable to perform a simple client TCP connect. The same problem is not observed on Linux. A nine-months old version of ncat also works fine.
The key error message is
libnsock select_loop(): nsock_loop error 10038: An operation was attempted on something that is not a socket.
There was no recent change in routine select_loop() in nsock/src/engine_select.c to provide an obvious explanation.
Details:
The following is observed on Windows 8 with stock ncat 7.60 (and also on Windows 7 with close-enough ncat r36949):
C:\temp>ncat -vv 10.128.24.212 21
Ncat: Version 7.60 ( https://nmap.org/ncat )
NCAT DEBUG: Using trusted CA certificates from C:\temp\ca-bundle.crt.
libnsock nsock_iod_new2(): nsock_iod_new (IOD #1)
libnsock nsock_connect_tcp(): TCP connection requested to 10.128.24.212:21 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [10.128.24.212:21]
Ncat: Connected to 10.128.24.212:21.
libnsock nsock_iod_new2(): nsock_iod_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [10.128.24.212:21] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26
libnsock select_loop(): nsock_loop error 10038: An operation was attempted on something that is not a socket.
Ncat: 0 bytes sent, 0 bytes received in 0.06 seconds.
The same version of ncat (r36949) on Ubuntu does not have the problem:
$ ncat -vv 10.128.24.212 21
Ncat: Version 7.60SVN ( https://nmap.org/ncat )
NCAT DEBUG: Using system default trusted CA certificates and those in /usr/share/ncat/ca-bundle.crt.
libnsock nsock_iod_new2(): nsock_iod_new (IOD #1)
libnsock nsock_connect_tcp(): TCP connection requested to 10.128.24.212:21 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [10.128.24.212:21]
Ncat: Connected to 10.128.24.212:21.
libnsock nsock_iod_new2(): nsock_iod_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [10.128.24.212:21] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26
libnsock nsock_trace_handler_callback(): Callback: READ SUCCESS for EID 18 [10.128.24.212:21] (20 bytes): 220 (vsFTPd 3.0.2)..
220 (vsFTPd 3.0.2)
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #1 [10.128.24.212:21] EID 34
An older version of ncat (r36483) on the same Windows 8 and Windows 7 also works fine:
C:\oldncat\ncat -vv 10.128.24.212 21
Ncat: Version 7.31SVN ( https://nmap.org/ncat )
NCAT DEBUG: Using trusted CA certificates from C:\oldncat\ca-bundle.crt.
NCAT DEBUG: Unable to load trusted CA certificates from C:\oldncat\ca-bundle.crt: error:02001002:system library:fopen:No such file or directory
libnsock nsock_iod_new2(): nsock_iod_new (IOD #1)
libnsock nsock_connect_tcp(): TCP connection requested to 10.128.24.212:21 (IOD #1) EID 8
libnsock nsock_trace_handler_callback(): Callback: CONNECT SUCCESS for EID 8 [10.128.24.212:21]
Ncat: Connected to 10.128.24.212:21.
libnsock nsock_iod_new2(): nsock_iod_new (IOD #2)
libnsock nsock_read(): Read request from IOD #1 [10.128.24.212:21] (timeout: -1ms) EID 18
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #2 [peer unspecified] EID 26
libnsock nsock_trace_handler_callback(): Callback: READ SUCCESS for EID 18 [10.128.24.212:21] (20 bytes): 220 (vsFTPd 3.0.2)..
220 (vsFTPd 3.0.2)
libnsock nsock_readbytes(): Read request for 0 bytes from IOD #1 [10.128.24.212:21] EID 34