<div dir="ltr">Thanks, yes this was my first guess. Anyway, due to too much (potential) of unexpected behavior of using spoofed address I dropped this idea.<div><br></div><div>I'm trying to make a syslog-ng relay server (of 4-5 different Cisco devices) to forward logs to Logstash server. Somehow i need to save SOURCE IP address of every log and add it to message when forwarding to syslog server. Is it possible ? Could someone show some guidelines ? The best way to leave the message untouched, just to add some field to syslog message (for example the end). Thanks</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Apr 9, 2020 at 11:09 AM Antal Nemes (anemes) <<a href="mailto:Antal.Nemes@oneidentity.com">Antal.Nemes@oneidentity.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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Hello,</div>
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There is `rp_filter` kernel feature that might affect you: <a href="https://www.theurbanpenguin.com/rp_filter-and-lpic-3-linux-security/" id="gmail-m_7356987925205466506LPNoLP833119" target="_blank">
https://www.theurbanpenguin.com/rp_filter-and-lpic-3-linux-security/</a></div>
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Or this may be other routing problem, firewall or selinux.</div>
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It would worth checking if the packet arrives to the next hop using tcpdump.<br>
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Br,</div>
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Antal<br>
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<div id="gmail-m_7356987925205466506divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> syslog-ng <<a href="mailto:syslog-ng-bounces@lists.balabit.hu" target="_blank">syslog-ng-bounces@lists.balabit.hu</a>> on behalf of Edvinas Kairys <<a href="mailto:edvinas.email@gmail.com" target="_blank">edvinas.email@gmail.com</a>><br>
<b>Sent:</b> Wednesday, April 8, 2020 19:57<br>
<b>To:</b> <a href="mailto:syslog-ng@lists.balabit.hu" target="_blank">syslog-ng@lists.balabit.hu</a> <<a href="mailto:syslog-ng@lists.balabit.hu" target="_blank">syslog-ng@lists.balabit.hu</a>><br>
<b>Subject:</b> [syslog-ng] mystique with spoof_address</font>
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<div> Hello, i installed (yum install) following version on Centos 7 box.
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<div>syslog-ng 3.5.6<br>
Installer-Version: 3.5.6<br>
Revision: <br>
Compile-Date: Dec 30 2015 19:57:24<br>
Available-Modules: affile,afprog,afsocket-notls,afsocket-tls,afsocket,afstomp,afuser,basicfuncs,confgen,cryptofuncs,csvparser,dbparser,linux-kmsg-format,syslogformat,system-source<br>
Enable-Debug: off<br>
Enable-GProf: off<br>
Enable-Memtrace: off<br>
Enable-IPv6: on<br>
Enable-Spoof-Source: on<br>
Enable-TCP-Wrapper: on<br>
Enable-Linux-Caps: on<br>
Enable-Pcre: on<br>
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<div>My goal is to forward syslog messages 'untouched' but to change the source address to original one. For that case i'm using spoof-address.</div>
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<div>My conf is like this:</div>
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<div>options {<br>
flush_lines (0);<br>
time_reopen (10);<br>
log_fifo_size (1000);<br>
chain_hostnames (off);<br>
use_dns (no);<br>
use_fqdn (no);<br>
create_dirs (no);<br>
keep_hostname (no);<br>
mark-freq (0);<br>
};<br>
</div>
<div>source s_network {<br>
</div>
<div> udp(ip(0.0.0.0) port(514) flags(no-parse));<br>
<br>
};<br>
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<div>destination d_syslog_tcp { network("10.13.33.125" transport("udp") port(5140) spoof-source(yes)); };<br>
</div>
<div>log { source(s_network); destination(d_syslog_tcp); };<br>
log { source(s_network); filter(f_default); destination(d_mesg); };<br>
# Source additional configuration files (.conf extension only)<br>
@include "/etc/syslog-ng/conf.d/*.conf"<br>
</div>
<div><br>
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<div>Strange thing, that when I enable spoof-source, some packets are not transmitted to the destination. Even TCPDUMP says that it's sent, but i dont see some logs on destination box.</div>
<div>Could it be something with spoof_source command ? Also i didn't compiled it because i saw that SPOOF functionality is on in syslog-ng -V output.</div>
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<div>Any suggestions ?</div>
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<div>Thanks</div>
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<div></div>
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