DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 9A8773894C3B
To: cygwin@cygwin.com
Subject: sshd.exe waits repeatedly with SYN_SENT for inaccessible ldap
Message-ID: <67ec7d7f-cac0-3a2a-4f85-1d42f0864b46@gmail.com>
Date: Fri, 22 Jan 2021 22:07:18 +0300
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.1
MIME-Version: 1.0
Content-Language: en-US
From: Ilya Basin via Cygwin <cygwin@cygwin.com>
Reply-To: basinilya@gmail.com
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: "Cygwin" <cygwin-bounces@cygwin.com>

Hi. The problem first appeared ten days ago. It now takes minutes to login as a domain user. Tcpview shows that sshd.exe is trying to connect an inaccessible server on the port 389 (ldap). If I close the socket using Tcpview, successful login happens sooner. Both password and public key logins are affected, but with a public key sshd.exe tries to connect that server multiple times. Also, if I don't close the sockets repeatedly, ssh disconnects from the SSH server after 2 minutes of silence before the "last login" line appears:

    $ time ssh -vvv localhost
    ...
    debug1: Offering public key:
    debug3: send packet: type 50
    debug2: we sent a publickey packet, wait for reply
    
    
    debug3: receive packet: type 60
    debug1: Server accepts key: 
    debug3: sign_and_send_pubkey: RSA
    debug3: sign_and_send_pubkey: signing using rsa-sha2-512
    debug3: send packet: type 50
    
    
    Connection closed by ::1 port 22
    
    real    2m0.292s
    user    0m0.045s
    sys     0m0.122s


Besedes, sshd.exe has a live connection on port 389 to another server all the time.


I can't see anything interesting in sshd log. At least the ldap ip address does not appear in the log.

    ...
    <TimeCreated SystemTime="2021-01-22T18:52:09.7210295Z" /> 
    <Data>sshd: PID 1786: debug1: temporarily_use_uid: 1087042/1049089 (e=18/18)</Data> 
      
    <TimeCreated SystemTime="2021-01-22T18:52:51.9304939Z" /> 
    <Data>sshd: PID 1786: debug1: trying public key file /home/basin/.ssh/authorized_keys</Data> 
    ...
    
    <TimeCreated SystemTime="2021-01-22T18:53:21.6284471Z" /> 
    <Data>sshd: PID 1786: debug1: temporarily_use_uid: 1087042/1049089 (e=18/18)</Data> 
    ...
    
    
    <TimeCreated SystemTime="2021-01-22T18:54:03.7296838Z" /> 
    <Data>sshd: PID 1786: debug1: trying public key file /home/basin/.ssh/authorized_keys</Data> 
    ...
    
    
    <TimeCreated SystemTime="2021-01-22T18:54:03.7296838Z" /> 
    <Data>sshd: PID 1786: debug1: monitor_child_preauth: basin has been authenticated by privileged process</Data> 
    ...
    
    
    <TimeCreated SystemTime="2021-01-22T18:54:09.6686942Z" /> 
    <Data>sshd: PID 1652: debug1: main_sigchld_handler: Child exited</Data> 

BTW, is it possible to make sshd write to a log file instead of Windows Event Log?


--
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple