Package: netcat-openbsd
Version: 1.130-1
Severity: important
This is netcat-openbsd 1.105-7
------------------------------
Command line is:
$ echo 'ehlo itsme' | nc.openbsd host.example.com 25
The output is:
220 host.example.com ESMTP Postfix
250-host.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
The simple trace is:
1 0.000000000 1.1.1.11 ? 1.1.1.1 TCP 74 47242?smtp(25) [SYN] Seq=0
Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=1188714834 TSecr=0 WS=128
2 0.000130857 1.1.1.1 ? 1.1.1.11 TCP 74 smtp(25)?47242 [SYN, ACK] Seq=0
Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=1189398612 TSecr=1188714834
WS=128
3 0.000171694 1.1.1.11 ? 1.1.1.1 TCP 66 47242?smtp(25) [ACK] Seq=1 Ack=1
Win=29312 Len=0 TSval=1188714834 TSecr=1189398612
4 0.000539830 1.1.1.11 ? 1.1.1.1 SMTP 77 C: ehlo itsme
5 0.000555726 1.1.1.11 ? 1.1.1.1 TCP 66 47242?smtp(25) [FIN, ACK] Seq=12
Ack=1 Win=29312 Len=0 TSval=1188714834 TSecr=1189398612
6 0.000682959 1.1.1.1 ? 1.1.1.11 TCP 66 smtp(25)?47242 [ACK] Seq=1 Ack=12
Win=29056 Len=0 TSval=1189398612 TSecr=1188714834
7 0.009776682 1.1.1.1 ? 1.1.1.11 SMTP 106 S: 220 host.example.com ESMTP
Postfix
8 0.009800662 1.1.1.11 ? 1.1.1.1 TCP 66 47242?smtp(25) [ACK] Seq=13
Ack=41 Win=29312 Len=0 TSval=1188714836 TSecr=1189398615
9 0.009807945 1.1.1.1 ? 1.1.1.11 SMTP 195 S: 250 host.example.com | 250
PIPELINING | 250 SIZE 10240000 | 250 VRFY | 250 ETRN | 250 ENHANCEDSTATUSCODES
| 250 8BITMIME | 250 DSN
10 0.009822556 1.1.1.11 ? 1.1.1.1 TCP 66 47242?smtp(25) [ACK] Seq=13
Ack=171 Win=30336 Len=0 TSval=1188714836 TSecr=1189398615
This is netcat-openbsd 1.130-1
------------------------------
Same command line:
$ echo 'ehlo itsme' | nc.openbsd host.example.com 25
There is _no_ output.
It seems nc.openbsd is closing the socket before reading/showing
whatever host.example.com returns. Note the two resets '[RST]'
bellow.
11 25.973506450 1.1.1.11 ? 1.1.1.1 TCP 74 47246?smtp(25) [SYN] Seq=0
Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=1188721327 TSecr=0 WS=128
12 25.973662894 1.1.1.1 ? 1.1.1.11 TCP 74 smtp(25)?47246 [SYN, ACK] Seq=0
Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=1189405106 TSecr=1188721327
WS=128
13 25.973690712 1.1.1.11 ? 1.1.1.1 TCP 66 47246?smtp(25) [ACK] Seq=1 Ack=1
Win=29312 Len=0 TSval=1188721327 TSecr=1189405106
14 25.973728427 1.1.1.11 ? 1.1.1.1 SMTP 77 C: ehlo itsme
15 25.973747259 1.1.1.11 ? 1.1.1.1 TCP 66 47246?smtp(25) [FIN, ACK] Seq=12
Ack=1 Win=29312 Len=0 TSval=1188721327 TSecr=1189405106
16 25.973845701 1.1.1.1 ? 1.1.1.11 TCP 66 smtp(25)?47246 [ACK] Seq=1 Ack=12
Win=29056 Len=0 TSval=1189405106 TSecr=1188721327
17 25.974788937 1.1.1.1 ? 1.1.1.11 SMTP 106 S: 220 host.example.com ESMTP
Postfix
18 25.974817575 1.1.1.11 ? 1.1.1.1 TCP 54 47246?smtp(25) [RST] Seq=13 Win=0
Len=0
^^^
19 25.974872212 1.1.1.1 ? 1.1.1.11 SMTP 195 S: 250 host.example.com | 250
PIPELINING | 250 SIZE 10240000 | 250 VRFY | 250 ETRN | 250 ENHANCEDSTATUSCODES
| 250 8BITMIME | 250 DSN
20 25.974896332 1.1.1.11 ? 1.1.1.1 TCP 54 47246?smtp(25) [RST] Seq=13 Win=0
Len=0
^^^
If I add the '-q1' option (wait one second after EOF on stdin) to the
command line:
$ echo 'ehlo itsme' | nc.openbsd -q1 host.example.com 25
then I get the expected output:
220 host.example.com ESMTP Postfix
250-host.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
Note, no '[RST]' in the packet trace.
1 0.000000000 1.1.1.11 ? 1.1.1.1 TCP 74 47742?smtp(25) [SYN] Seq=0
Win=29200 Len=0 MSS=1460 SACK_PERM=1 TSval=1189159653 TSecr=0 WS=128
2 0.000144981 1.1.1.1 ? 1.1.1.11 TCP 74 smtp(25)?47742 [SYN, ACK] Seq=0
Ack=1 Win=28960 Len=0 MSS=1460 SACK_PERM=1 TSval=1189843431 TSecr=1189159653
WS=128
3 0.000173801 1.1.1.11 ? 1.1.1.1 TCP 66 47742?smtp(25) [ACK] Seq=1 Ack=1
Win=29312 Len=0 TSval=1189159653 TSecr=1189843431
4 0.000208860 1.1.1.11 ? 1.1.1.1 SMTP 77 C: ehlo itsme
5 0.000338115 1.1.1.1 ? 1.1.1.11 TCP 66 smtp(25)?47742 [ACK] Seq=1 Ack=12
Win=29056 Len=0 TSval=1189843432 TSecr=1189159653
6 0.001715233 1.1.1.1 ? 1.1.1.11 SMTP 106 S: 220 host.example.com ESMTP
Postfix
7 0.001733564 1.1.1.11 ? 1.1.1.1 TCP 66 47742?smtp(25) [ACK] Seq=12
Ack=41 Win=29312 Len=0 TSval=1189159653 TSecr=1189843432
8 0.001875842 1.1.1.1 ? 1.1.1.11 SMTP 195 S: 250 host.example.com | 250
PIPELINING | 250 SIZE 10240000 | 250 VRFY | 250 ETRN | 250 ENHANCEDSTATUSCODES
| 250 8BITMIME | 250 DSN
9 0.001895568 1.1.1.11 ? 1.1.1.1 TCP 66 47742?smtp(25) [ACK] Seq=12
Ack=170 Win=30336 Len=0 TSval=1189159653 TSecr=1189843432
10 1.002139332 1.1.1.11 ? 1.1.1.1 TCP 66 47742?smtp(25) [FIN, ACK] Seq=12
Ack=170 Win=30336 Len=0 TSval=1189159903 TSecr=1189843432
11 1.002387350 1.1.1.1 ? 1.1.1.11 TCP 66 smtp(25)?47742 [FIN, ACK] Seq=170
Ack=13 Win=29056 Len=0 TSval=1189843682 TSecr=1189159903
12 1.002412151 1.1.1.11 ? 1.1.1.1 TCP 66 47742?smtp(25) [ACK] Seq=13
Ack=171 Win=30336 Len=0 TSval=1189159903 TSecr=1189843682
-- System Information:
Debian Release: stretch/sid
APT prefers testing
APT policy: (500, 'testing'), (99, 'unstable'), (59, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386
Kernel: Linux 4.4.0-1-amd64 (SMP w/8 CPU cores)
Locale: LANG=, LC_CTYPE= (charmap=ANSI_X3.4-1968)
Shell: /bin/sh linked to /bin/bash
Init: sysvinit (via /sbin/init)
Versions of packages netcat-openbsd depends on:
ii libbsd0 0.8.3-1
ii libc6 2.24-3
netcat-openbsd recommends no packages.
netcat-openbsd suggests no packages.
-- no debconf information
Cheers,
--
Cristian
