Synchronet v3.20d-Win32 (install) has been released (Mar-2025).

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faq:tcpip [2024/11/02 13:48] – [Ports] List the disabled service ports too (for reference) digital manfaq:tcpip [2025/01/29 23:12] (current) – [SSH Session Key] Added some common logged ssh errors nelgin
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 In general, you need to check your Synchronet Mail Server window/log output for details about why Internet e-mail delivery attempts may be failing.  In general, you need to check your Synchronet Mail Server window/log output for details about why Internet e-mail delivery attempts may be failing. 
  
 +==== GMail ====
 +:?: **Question:**\\
 +Why can't I send Internet e-mail from my BBS to GMail.com?
 +
 +Example:
 +  cvs.synchro.net reporting delivery failure of message
 +  from Someone to annyone@gmail.com
 +  
 +  Reason:
 +  gmail-smtp-in.l.google.com replied with:
 +  "550 5.7.26  https://support.google.com/mail/answer/81126#authentication
 +  d9443c01a7336-21a919d2ef1si90834815ad.334 - gsmtp"
 +  instead of the expected reply:
 +  "250 ..."        
 +
 +:!: **Answer:**\\
 +GMail.com requires mail severs have a valid **SPF** DNS record to send email to their servers. This requirement from Google is an anti-spoofing/SPAM measurement and nothing to do specifically with the Synchronet Mail Server. [[https://support.google.com/a/answer/33786?sjid=18257063204175362891-NC|Here are helpful instructions from Google on how to set up an SPF record your domain]].
 +
 +An SPF record is a specially formatted DNS **TXT** (text) record. You can check if your domain has an SPF record by querying the DNS for TXT records for your domain using common network tools provided with your OS such as ''host'', ''dig'', and ''nslookup''.
 +
 +  $ host -t txt vert.synchro.net
 +  vert.synchro.net descriptive text "v=spf1 mx a -all"
 +
 +If you are [[howto:relay_smtp|relaying your outbound Internet mail through Vertrauen]], then it is Vertrauen's mail servers that you need to reference in your domain's SPF record (not your own):
 +  mail.synchro.net
 +
 +If you are relaying your outbound Internet mail through Vertrauen **and** [[howto:vert_mx|using Vertrauen as your inbound Internet Mail Exchange (MX)]], then setting your domain's SPF record to just the following will suffice:
 +  v=spf1 mx a -all
 +  
 +If you are using the Synchronet dynamic DNS service to have/update a ''//yourbbs//.synchro.net'' hostname, then see [[module:dyndns#SPF]] for details on how to create the appropriate SPF record.
 ===== Receive Mail ===== ===== Receive Mail =====
  
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 You should also see evidence of the successful SMTP connection to the server in your Synchronet Mail Server window/log output. If you do not, then it's likely that your firewall or Internet Service Provider is blocking incoming connections to TCP port 25. Before concluding this is the case, verify that the remote Telnet client can connect to other SMTP servers first (e.g. ''vert.synchro.net'', TCP port 25). If it cannot, then this remote client probably has restrictions on which (if any) connections he can make to TCP port 25. Try using a different, less restricted, remote Internet connection for your test.  You should also see evidence of the successful SMTP connection to the server in your Synchronet Mail Server window/log output. If you do not, then it's likely that your firewall or Internet Service Provider is blocking incoming connections to TCP port 25. Before concluding this is the case, verify that the remote Telnet client can connect to other SMTP servers first (e.g. ''vert.synchro.net'', TCP port 25). If it cannot, then this remote client probably has restrictions on which (if any) connections he can make to TCP port 25. Try using a different, less restricted, remote Internet connection for your test. 
  
-If your firewall or Internet Service Provider is blocking incoming connections to TCP port 25 (many consumer-class ISPs do), then you won't be able to receive Internet e-mail on your BBS. Fixing your firewall configuration is rather simple, but changing ISPs is often not. One possible work-around is having a mail proxy (3rd party server) receive the e-mail for you and forward it to a non-standard, non-filtered/blocked SMTP port. Many Dynamic DNS services offer this service [[http://www.dyndns.com/services/mailhop/relay.html|for a fee]]. Or a fellow sysop may be able and willing to perform this service for you as a favor. +If your firewall or Internet Service Provider is blocking incoming connections to TCP port 25 (many consumer-class ISPs do), then you won't be able to receive Internet e-mail on your BBS. Fixing your firewall configuration is rather simple, but changing ISPs is often not. One possible work-around is having a mail proxy (3rd party server) receive the e-mail for you and forward it to a non-standard, non-filtered/blocked SMTP port. Many Dynamic DNS services offer this Mail Exchange (MX) service [[http://www.dyndns.com/services/mailhop/relay.html|for a fee]]. [[howto:vert_mx|Or a fellow sysop may be able and willing to perform this service for you as a favor]]. 
  
 ===== FTP Connect ===== ===== FTP Connect =====
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 These files (''cryptlib.key'' and ''ssl.cert'') are encrypted with the Synchronet //system password//, so if the system password is changed then these files must also be regenerated. The files are automatically recreated by //sbbs// upon startup if they do not already exist. These files (''cryptlib.key'' and ''ssl.cert'') are encrypted with the Synchronet //system password//, so if the system password is changed then these files must also be regenerated. The files are automatically recreated by //sbbs// upon startup if they do not already exist.
 +
 +===== SSH Errors =====
 +:?: **Question:**\\
 +Should I be concerned about ssh errors in my log files?
 +
 +:!: **Answer**\\
 +A number of ssh errors are generated mainly due to clients disconnecting or not actually using a valid ssh client, such as port scanners or bots. Some of these errors are
 +
 +  'Internal consistency check failed' (-16) setting session active
 +  
 +  'ENOTCONN: Socket is not connected' (-42) setting session active
 +  
 +  'Error reading client's SSH identifier string: ETIMEDOUT: Function timed out before completion' (-41) setting session active
 +  
 +  No data was read because the remote system closed the connection (recv() == 0)' (-41) setting session active
 +  
 +  'Need resource to proceed' (-50) setting session active
 +  
 +
 ===== See Also ===== ===== See Also =====
   * [[:server:|Servers]]   * [[:server:|Servers]]

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