Hello, i'm trying to capture NetFlow v9 (NAT translation from proprietary hardware). I need to filter some subnets and send to another NetFlow colletror.

When i run: nfcapd -T nsel,nel -l /var/log/nat/netflow/ -p 5556 -t 2 -x "nfreplay -r /var/log/nat/netflow/%f -f /srv/scripts/nfdump.filter -v 9"

i got NetFlow without right template and fields:

Flow Record: Flags = 0x06 NETFLOW v9, Unsampled label = export sysid = 1 size = 56 first = 1602186349 [2020-10-08 22:45:49] last = 1602186349 [2020-10-08 22:45:49] msec_first = 0 msec_last = 0 src addr = 10.4.218.117 dst addr = 31.13.72.8 src port = 44460 dst port = 443 fwd status = 0 tcp flags = 0x00 ........ proto = 6 TCP (src)tos = 0 (in)packets = 0 (in)bytes = 0

Original data is like that:

Flow Record: Flags = 0x46 EVENT, Unsampled label = export sysid = 10 size = 100 first = 1602186433 [2020-10-08 22:47:13] last = 1602186433 [2020-10-08 22:47:13] msec_first = 0 msec_last = 0 src addr = 10.4.80.208 dst addr = 64.233.161.157 src port = 46963 dst port = 443 fwd status = 0 tcp flags = 0x00 ........ proto = 6 TCP (src)tos = 0 (in)packets = 0 (in)bytes = 0 connect ID = 0 fw event = 1: CREATE fw ext event = 0: Ignore secgroup tag = 0 Event time = 1602186433000 [2020-10-08 22:47:13.000] src xlt port = 5271 dst xlt port = 443 src xlt ip = 31.185.7.194 dst xlt ip = 64.233.161.157 nat event = 1: CREATE ingress VRF = 0 egress VRF = 0

How to resend filtered netflow with NEL/NSEL data using nfreplay or may be other open source projects?

Currently nfreplay does not support replaying NSEL/NAT event records. It only supports plain v9 without those event specific fields.

nfdump-1.7.x may be able to forward more special NAT/NSEL elements

Hello! It's a goot news, but can't build 1.7 unicorn :)

https://pastebin.com/LW24At9F

make all-recursive make[1]: Entering directory '/usr/src/nfdump-unicorn' Making all in . make[2]: Entering directory '/usr/src/nfdump-unicorn' make[2]: Leaving directory '/usr/src/nfdump-unicorn' Making all in bin make[2]: Entering directory '/usr/src/nfdump-unicorn/bin' make all-am make[3]: Entering directory '/usr/src/nfdump-unicorn/bin' /bin/bash ../libtool --tag=CC --mode=link gcc -g -O3 -std=gnu11 -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wmissing-noreturn -fno-strict-aliasing -DNSEL -o nfcapd nfcapd-nfcapd.o nfcapd-nfstatfile.o nfcapd-launch.o nfcapd-nfnet.o nfcapd-collector.o nfcapd-netflow_v1.o nfcapd-netflow_v5_v7.o nfcapd-netflow_v9.o nfcapd-ipfix.o nfcapd-bookkeeper.o nfcapd-expire.o -lnfdump -lresolv -lbz2 libtool: link: gcc -g -O3 -std=gnu11 -Wall -Wstrict-prototypes -Wmissing-prototypes -Wmissing-declarations -Wmissing-noreturn -fno-strict-aliasing -DNSEL -o .libs/nfcapd nfcapd-nfcapd.o nfcapd-nfstatfile.o nfcapd-launch.o nfcapd-nfnet.o nfcapd-collector.o nfcapd-netflow_v1.o nfcapd-netflow_v5_v7.o nfcapd-netflow_v9.o nfcapd-ipfix.o nfcapd-bookkeeper.o nfcapd-expire.o /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so -lresolv -lbz2 /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to pthread_detach' /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to __atomic_compare_exchange_16' /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to __atomic_load_16' /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to pthread_join' /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to __atomic_store_16' /usr/src/nfdump-unicorn/bin/.libs/libnfdump.so: undefined reference to pthread_create' collect2: error: ld returned 1 exit status Makefile:946: recipe for target 'nfcapd' failed make[3]: *** [nfcapd] Error 1 make[3]: Leaving directory '/usr/src/nfdump-unicorn/bin' Makefile:804: recipe for target 'all' failed make[2]: *** [all] Error 2 make[2]: Leaving directory '/usr/src/nfdump-unicorn/bin' Makefile:413: recipe for target 'all-recursive' failed make[1]: *** [all-recursive] Error 1 make[1]: Leaving directory '/usr/src/nfdump-unicorn' Makefile:345: recipe for target 'all' failed

Seems to be missing pthread and atomic libs in Makefile-s
LIBS = -lresolv -lbz2 -lpthread -latomic

I have success to build binaries,

nfcapd -V

nfcapd: Version: 1.7.0

nfreplay seems not support NEL/NSEL

Sample data in dump low Record: Flags = 0x00 FLOW, Unsampled Elements = 6: 1 2 13 21 23 26 size = 132 engine type = 0 engine ID = 10 export sysid = 6 first = 0 [.000] last = 0 [.000] received at = 1603802049510 [2020-10-27 15:34:09.510] proto = 6 TCP tcp flags = 0x00 ........ src port = 48796 dst port = 443 src tos = 0 in packets = 0 in bytes = 0 src addr = 10.4.221.187 dst addr = 94.100.185.164 ip exporter = 10.4.1.15 src xlt ip = 31.185.7.202 dst xlt ip = 94.100.185.164 src xlt port = 5542 dst xlt port = 443 nat event = 1: ADD Event time = 1603802049000 [2020-10-27 15:34:09.000] ingress VRF = 0 egress VRF = 0

data after nfreplay looks like

Flow Record: Flags = 0x00 FLOW, Unsampled Elements = 3: 1 2 13 size = 84 engine type = 91 engine ID = 85 export sysid = 1 first = 0 [.000] last = 0 [.000] received at = 1603803946931 [2020-10-27 16:05:46.931] proto = 6 TCP tcp flags = 0x00 ........ src port = 48788 dst port = 443 src tos = 0 in packets = 0 in bytes = 0 src addr = 10.4.221.187 dst addr = 94.100.185.164 ip exporter = 127.0.0.1

May be i'm doing something wrong?

No - you are doing all right. But these extension for NSEL/NAT forwarding are not yet in.

With the code changes in that latest master repo, you can forward records natively with nfdump protocol 250. Use nfreplay -v 250 .... and make sure the receiving end is an up to date nfcapd.

As this is now integrated, I close the ticket.