Hello Tom,
I do not have access to the web application but I tried the debuging option now and send you the output. I also make an external check and foud out that the connection time is very high. Maybe this is the problem but I do not understand this because the system is reachable as normal.
SMTP Connection Time 5.912 seconds
SMTP Transaction Time 8.440 seconds
Exim version 4.82 uid=0 gid=0 pid=4897 D=fbb95cfd
Berkeley DB: Berkeley DB 5.3.28: (September 9, 2013)
Support for: crypteq iconv() IPv6 PAM Perl Expand_dlfunc GnuTLS move_frozen_messages Content_Scanning DKIM Old_Demime
Lookups (built-in): lsearch wildlsearch nwildlsearch iplsearch cdb dbm dbmjz dbmnz dnsdb dsearch ldap ldapdn ldapm mysql nis nis0 passwd pgsql sqlite
Authenticators: cram_md5 cyrus_sasl dovecot plaintext spa
Routers: accept dnslookup ipliteral iplookup manualroute queryprogram redirect
Transports: appendfile/maildir/mailstore/mbx autoreply lmtp pipe smtp
Fixed never_users: 0
Size of off_t: 8
Compiler: GCC [4.8.2]
Library version: GnuTLS: Compile: 2.12.23
Runtime: 2.12.23
Library version: Cyrus SASL: Compile: 2.1.25
Runtime: 2.1.25 [Cyrus SASL]
Library version: PCRE: Compile: 8.31
Runtime: 8.31 2012-07-06
Total 19 lookups
Library version: MySQL: Compile: 5.5.35 [(Ubuntu)]
Runtime: 5.5.40
Library version: SQLite: Compile: 3.8.2
Runtime: 3.8.2
WHITELIST_D_MACROS: "OUTGOING"
TRUSTED_CONFIG_LIST: "/etc/exim4/trusted_configs"
changed uid/gid: forcing real = effective
uid=0 gid=0 pid=4897
auxiliary group list: <none>
seeking password data for user "root": cache not available
getpwnam() succeeded uid=0 gid=0
changed uid/gid: calling tls_validate_require_cipher
uid=111 gid=117 pid=4898
auxiliary group list: <none>
tls_validate_require_cipher child 4898 ended: status=0x0
configuration file is /var/lib/exim4/config.autogenerated
log selectors = 00000ffc 00232001
cwd=/root 5 args: exim -bd -d -oX 25
trusted user
admin user
originator: uid=0 gid=0 login=root name=root
4897 daemon_smtp_port overridden by -oX:
4897 <: 25
4897 listening on all interfaces (IPv6) port 25
4897 listening on all interfaces (IPv4) port 25
4897 changed uid/gid: running as a daemon
4897 uid=111 gid=117 pid=4897
4897 auxiliary group list: 8 117
4897 LOG: MAIN
4897 exim 4.82 daemon started: pid=4897, no queue runs, listening for SMTP on port 25 (IPv6 and IPv4)
4897 set_process_info: 4897 daemon: no queue runs, listening for SMTP on port 25 (IPv6 and IPv4)
4897 daemon running with uid=111 gid=117 euid=111 egid=117
4897 Listening...
4897 Connection request from x.x.x.x port 56821
4897 search_tidyup called
4897 1 SMTP accept process running
4897 Listening...
4901 host in rfc1413_hosts? yes (matched "*")
4901 doing ident callback
4901 ident connection to x.x.x.x failed: Connection timed out
4901 sender_fullhost = [x.x.x.x]
4901 sender_rcvhost = [x.x.x.x]
4901 Process 4901 is handling incoming connection from [x.x.x.x]
4901 host in host_lookup? yes (matched "*")
4901 looking up host name for x.x.x.x
4901 DNS lookup of 7.41.55.65.in-addr.arpa (PTR) gave HOST_NOT_FOUND
4901 returning DNS_NOMATCH
4901 IP address lookup using gethostbyaddr()
4901 IP address lookup failed: h_errno=1
4901 LOG: host_lookup_failed MAIN
4901 no host name found for IP address x.x.x.x
4901 sender_fullhost = [x.x.x.x]
4901 sender_rcvhost = [x.x.x.x]
4901 set_process_info: 4901 handling incoming connection from [x.x.x.x]
4901 host in host_reject_connection? no (option unset)
4901 host in sender_unqualified_hosts? no (option unset)
4901 host in recipient_unqualified_hosts? no (option unset)
4901 host in helo_verify_hosts? no (option unset)
4901 host in helo_try_verify_hosts? no (option unset)
4901 host in helo_accept_junk_hosts? no (option unset)
4901 using ACL "acl_check_spammers"
4901 processing "accept"
4901 check hosts = +whitelist
4901 search_open: iplsearch "/etc/exim4/white-blocks.conf"
4901 search_find: file="/etc/exim4/white-blocks.conf"
4901 key="x.x.x.x" partial=-1 affix=NULL starflags=0
4901 LRU list:
4901 6/etc/exim4/white-blocks.conf
4901 End
4901 internal_search_find: file="/etc/exim4/white-blocks.conf"
4901 type=iplsearch key="x.x.x.x"
4901 file lookup required for x.x.x.x
4901 in /etc/exim4/white-blocks.conf
4901 lookup failed
4901 host in "net-iplsearch;/etc/exim4/white-blocks.conf"? no (end of list)
4901 host in "+whitelist"? no (end of list)
4901 accept: condition test failed in ACL "acl_check_spammers"
4901 processing "drop"
4901 check hosts = +spammers
4901 search_open: iplsearch "/etc/exim4/spam-blocks.conf"
4901 search_find: file="/etc/exim4/spam-blocks.conf"
4901 key="x.x.x.x" partial=-1 affix=NULL starflags=0
4901 LRU list:
4901 6/etc/exim4/spam-blocks.conf
4901 6/etc/exim4/white-blocks.conf
4901 End
4901 internal_search_find: file="/etc/exim4/spam-blocks.conf"
4901 type=iplsearch key="x.x.x.x"
4901 file lookup required for x.x.x.x
4901 in /etc/exim4/spam-blocks.conf
4901 lookup failed
4901 host in "net-iplsearch;/etc/exim4/spam-blocks.conf"? no (end of list)
4901 host in "+spammers"? no (end of list)
4901 drop: condition test failed in ACL "acl_check_spammers"
4901 processing "accept"
4901 accept: condition test succeeded in ACL "acl_check_spammers"
4901 SMTP>> 220 MAILSERVER ESMTP Exim 4.82 Ubuntu Fri, 05 Dec 2014 11:36:51 +0100
4901 Process 4901 is ready for new message
4901 smtp_setup_msg entered
4901 SMTP>> 421 MAILSERVER lost input connection
4901 LOG: smtp_connection MAIN
4901 SMTP connection from [x.x.x.x] lost
4901 search_tidyup called
4897 child 4901 ended: status=0x100
4897 normal exit, 1
4897 0 SMTP accept processes now running
4897 Listening...
-----Ursprüngliche Nachricht-----
Gesendet: Freitag, 05 Dezember 2014 um 10:58:42 Uhr
Von: "Thomas Hager" <duke@???>
An: exim-users@???
Betreff: Re: [exim] Smtp not possible from some clients
On 2014-12-04 20:44, matthiasmueller07@??? wrote:
> Hello,
Hi,
> I have a problem with the smtp connection from some clients web
> application which is using a smtp connection to send mails. The output
> only says that no smtp conenction is possible, therfore I do not have
> a detailed error message.
Can you activate some sort of debug logging in this web application?
> On the server side I searched the firewall entries, the receiving of
> the TCP packages and the logs. I only found the following log entrie,
> when the Client is connecing to the smtp server which seems to be
> failed.
Did you analyse the TCP dump in Wireshark? Can you see a valid SMTP
handshake between the web app and your Exim server?
Can you manually initiate an SMTP session from the web application's
host?
Is the web application using an encrypted or unencrypted connection?
If it's encrypted a common error might be that the web application fails
to
validate your mail servers certificate and aborts the connection.
> Message:
> no host name found for IP address xx.xx.xx.xx
That's just informational and would not cause Exim to abort a
connection.
> I searched very long time but do not found a real solution I can do on
> my side. I tried to whitelist the ip address or Change the host_lookup
> option but the issue still occur. Also I checked installed fail2ban
> logs but there is also no helpful entry. The Connection from outher
> Clients is working so it seems to be not a general issue.
IIRC, fail2ban is for blocking brute force SSH login attempts, it won't
interfere
with SMTP.
How flexible is your environment? If you can't enable debugging in the
web application
and Wireshark is no help either, you could always run Exim in debugging
mode on a
different port or server and see what Exim has to say about this
connectivity issues.
Hth,
Tom.
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