Syslog-NG: 2 logs from the same source written differently - splunk

Question

I have 2 sets of logs. Each is going to their own syslog server. But the source of the logs is the same - a palo alto prisma vpn.
For whatever reason, Syslog-Server A (the oldest source) writes the logs like this (in bold):
Nov 22 15:08:03 34 456
But my newest Syslog Server, B, writes the logs like this (in bold):
Nov 22 15:08:03 34.0.0.1 456
This is a problem. Because, on each syslog-ng server, we have a Splunk Universal Forwarder that forwards the logs to an index. We use the Palo Tech Add-On to parse the data.
It appears the TA is expected to parse the incoming data with this field:
Nov 22 15:08:03 34 456
Any other way breaks parsing. I have my new syslog-ng file (for the new server - B) written as below:
#version:3.31
#include "scl.conf"
options {
flush_lines (0);
time_reopen (10);
log_fifo_size (1000);
chain_hostnames (off);
use_dns (no); #was yes
use_fqdn (no); #was yes
create_dirs (no);
keep_hostname (no); #was yes
};
source vpn_encrypted_log_traffic {
network(
ip(0.0.0.0)
port(6514)
transport("tls")
tls(
cert-file("/etc/syslog-ng/certs/prv.cer")
key-file("/etc/syslog-ng/certs/prv.key")
peer_verify(optional-untrusted)
)
);
};
destination prisma{ file("/directory/log.log") create_dir(yes) ); }
log { source(vpn_encrypted_log_traffic); destination(prisma); };
And the old syslog server (A) just has this:
#version:3.5
#include "scl.conf"
options {
time-reap (30);
keep_hostname (no); #was yes
};
source vpn_encrypted_log_traffic {
network(
ip(0.0.0.0)
port(6514)
transport("tls")
tls(
cert-file("/etc/syslog-ng/certs/prv.cer")
key-file("/etc/syslog-ng/certs/prv.key")
peer_verify(optional-untrusted)
)
);
};
destination prisma{ file("/directory/log.log") create_dir(yes) ); }
log { source(vpn_encrypted_log_traffic); destination(prisma); };
I can only think the problem exists in Prisma. But the configs look 1-to-1 to me.

Answer 1

34.0.0.1 is the hostname/IP address part of a BSD syslog message.
use_dns(no); keep_hostname(no); means this part of the message will be replaced with server B's IP address.
keep_hostname(yes) can be used to leave the hostname intact.