You may have an older system or appliance that can transmit syslog data. You can use filebeat to accept that data and store it in Elasticsearch.
Install filebeat and test the reception the /tmp.
Enable and configure. Internet rumor has it that it’s UDP only so the config above reflects that. Interpreting the output requires parsing the message section detailed in the filter log format docs.
'5,,,1000000103,bge1.1099,match,block,in,4,0x0,,64,0,0,DF,17,udp,338,10.99.147.15,255.255.255.255,2048,30003,318'
'5,,,1000000103,bge2,match,block,in,4,0x0,,84,1,0,DF,17,udp,77,157.240.18.15,205.133.125.165,443,61343,57'
'222,,,1000029965,bge2,match,pass,out,4,0x0,,128,27169,0,DF,6,tcp,52,205.133.125.142,205.133.125.106,5225,445,0,S,1248570004,,8192,,mss;nop;wscale;nop;nop;sackOK'
'222,,,1000029965,bge2,match,pass,out,4,0x0,,128,11613,0,DF,6,tcp,52,205.133.125.142,211.24.111.75,15305,445,0,S,2205942835,,8192,,mss;nop;wscale;nop;nop;sackOK'