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First of all, you have to replace -j LOG in your rules with -j NFLOG this will stop iptables from logging to standard syslog and switch to ...

Linux Kernel with NFLOG (CONFIG_NETFILTER_XT_TARGET_NFLOG). Effective UID 0 (root) or the CAP_NET_ADMIN capability. According to the iptables-extensions (8) manual page, NFLOG usually passes packets to a multicast group of a netlink socket which requires CAP_NET_ADMIN as documented in the netlink (7) manual page. Examples:

13.02.2014 · At work, I needed to log and block SSLv3 connections on ports 993 (IMAPS) and 995 (POP3S) using iptables. So, I combined Gert van Dijk's How to take down SSLv3 in your network using iptables firewall?(POODLE) with Prevok's answer and came up with this: iptables -N SSLv3 iptables -A SSLv3 -j LOG --log-prefix "SSLv3 Client Hello detected: " iptables -A SSLv3 -j DROP …

19.12.2017 · iptables version: -A INPUT -m limit --limit 5/min -j LOG --log-prefix "INPUT dropped: " --log-level 7 nflog version – note that you need to set the group as well.

# iptables -A INPUT -m owner --uid-owner 1000 -j NFLOG --nflog-group 30 # iptables -A OUTPUT -m owner --uid-owner 1000 -j NFLOG --nflog-group 30 Yes, it is necessary. No, your proposal would not match any incoming packets (perhaps it does match traffic on the local machine, but definitely not external network traffic).

iptables nflog traffic dump ... tcpdump: nflog:5: No such device exists ... i looks as nflog does not work but im not sure how and why.

--nflog-group nlgroup The netlink group (0 - 2^16-1) to which packets are (only applicable for nfnetlink_log). The default value is 0. --nflog-prefix prefix A prefix string to include in the log message, up to 64 characters long, useful for distinguishing messages in the logs. --nflog-range size This option has never worked, use --nflog-size ...

NFLOG¶. This target provides logging of matching packets. When this target is set for a rule, the Linux kernel will pass the packet to the loaded logging ...

Just a "couple of hours" late :P but I'll write it anyway. As far as I know when using nflog you need to set the group as well, like this; ...

Presumably the iptables command makes some special ioctl calls or something to configure the firewall. Is there a C library that can be used to ...

20.07.2017 · iptables有几个日志记录的target (LOG, ULOG, NFLOG), LOG只是简单的记录包头信息到系统日志，而ULOG， NFLOG则可以把整个数据包发到应用层，应用层可以通过解析数据包来记录自己想要的信息。 大致的过程是这样：内核数据包走到iptables的钩子点上，如果数据包和规则匹配，就通过netlink把这个数据包多播到多播组，然后应用层通过netlink来接受这个数据包。 …

Jul 24, 2021 · iptables -A INPUT -p tcp --sport 1234 --nflog-prefix 'example block' -j DROP out: iptables v1.8.4 (legacy): unknown option "--nflog-prefix" Try `iptables -h' or 'iptables --help' for more information" but ebtables accepts it (at least it doesn't give an error):

01.08.2018 · Create iptables firewall that will allow already established connections, incoming icmp and ssh, outgoing icmp, ntp, dns, ssh, http and https. It will also log invalid packets and those dropped ones.

Aug 01, 2018 · tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on nflog:12, link-type NFLOG (Linux netfilter log messages), capture size 262144 bytes 16:40:32.707438 IP raspberrypi.55362 > debian.local.ssh: Flags [S], seq 2507142205, win 29200, options [mss 1460,sackOK,TS val 105615136 ecr 0,nop,wscale 6], length 0 16:40 ...

# iptables -A INPUT -p tcp -m tcp --sport 80 -j NFLOG --nflog-group 40 # iptables -A OUTPUT -p tcp -m tcp --dport 80 -j NFLOG --nflog-group 40 # dumpcap -i nflog:40 -w port-80.pcap Caveats The maximum payload size that can be captured is 65531 bytes (65535 is the maximum TLV length, minus two bytes for the length, minus two bytes for the NFULA ...

Define two new plugin stacks inside /etc/ulogd.conf file. stack=firewall11:NFLOG,base1:BASE,ifi1:IFINDEX,ip2str1:IP2STR,print1:PRINTPKT,emu11: ...

I guess you can at most do something like this: -N log_and_drop -A log_and_drop -j NFLOG --nflog-prefix "shared prefix" -A log_and_drop -j DROP -A INPUT -p ...

24.07.2021 · iptables -A INPUT -p tcp --sport 1234 -j NFLOG --nflog-prefix 'example block' iptables -A INPUT -p tcp --sport 1234 -j DROP I want to simplify this rules. I …

20.05.2020 · Logging traffic blocked by the nftables or iptables firewall rules is necessary for debugging the firewall rules and to be alerted to local software problems. Any packet matching a rule can be logged by using -j LOG target for iptables or log statement for nftables. Logging packet has no effect on the packet's disposition, however.

Linux Kernel with NFLOG (CONFIG_NETFILTER_XT_TARGET_NFLOG). Effective UID 0 (root) or the CAP_NET_ADMIN capability. According to the iptables- ...

--nflog-group nlgroup The netlink group (0 - 2^16-1) to which packets are (only applicable for nfnetlink_log). The default value is 0. --nflog-prefix prefix A prefix string to include in the log message, up to 64 characters long, useful for distinguishing messages in the logs. --nflog-range size This option has never worked, use --nflog-size ...

I set up my iptables rules by following this wiki page. But I only added one rule. iptables -A INPUT -j NFLOG --nflog-prefix "INPUT:DROP:"…

Overview

NFLOG. This target provides logging of matching packets. When this target is set for a rule, the Linux kernel will pass the packet to the loaded ...

NFLOG is the newer, generic (layer3 independent) logging framework for 2.6 kernels based on the original ULOG but implemented via libnfnetlink Both will send logs to ulogd which will then log via whatever output plugin you choose. Use ULOG if you are stuck with ulogd-1.x as 1.x might not play nicely with NFLOG.

# iptables -A INPUT -m owner --uid-owner 1000 -j NFLOG --nflog-group 30 # iptables -A OUTPUT -m owner --uid-owner 1000 -j NFLOG --nflog-group 30 Yes, it is necessary. No, your proposal would not match any incoming packets (perhaps it does match traffic on the local machine, but definitely not external network traffic).