netfilter connection tracking

10 More Discussions You Might Find Interesting

1. Cybersecurity

How to use Netfilter properly with IPv6?

Hello, on a PC with Debian 8 I try to use a Bash script with Netfilter rules so that only traffic goes in and out that is wanted. For that I set all 3 default policies to "drop". The machine uses DHCP to get its IP, gateway and DNS. And I never checked so I was quite surprised that my...

2. Cybersecurity

Experience with libvirt netfilter API

Hi all, I would like to get some ideas and opinions on matter of libvirt netfilter application in KVM environment. I am looking for some easy way to control it with an API and possible experience with that and its performance in real life application. Thanks for all ideas

3. Linux

C, LKM, netfilter, PF_PACKET and ARP.

Hello, Everyone knows that with PF_PACKET sockets one can "sniff" a determinated frame from the network device, but just that, see the frame without altering its action on the receiving host. What i want is to "intercept" the incoming frame and pass it through some rules, and if it doesn't pass...

4. IP Networking

Routing by connection tracking

Hello, I have switch port, that allows only a single MAC/IP connected to it. - But, I would like to connect two hosts, without any additional private network. (No NAT.) Therefore the plan is adding a linux router doing proxy-arp with three interfaces, one for host1, one for host2 and one...

5. Solaris

Solaris 10 ftp connection problem (connection refused, connection timed out)

Hi everyone, I am hoping anyone of you could help me in this weird problem we have in 1 of our Solaris 10 servers. Lately, we have been having some ftp problems in this server. Though it can ping any server within the network, it seems that it can only ftp to a select few. For most servers, the...

6. Linux

netfilter / iptables

HI, Is the Netfilter and IPtables same? Thanks & Regards Arun

7. Cybersecurity

Netfilter conntracking for P2P protocols (edonkey, bittorent...)

Hi everyone, I would like to allow multi users to access P2P networks, so I wonder if there's a way to tracking these kind of protocols with netfilter, and also compatibility with nat, like the module conntrack_ftp seems to do with the FTP protocol. Thanks guys.

8. Programming

extending netfilter...plz help

Hello friends i'm trying to extend iptables to include a target by which we can change the packet type field of a packet. For this i created a kernel module and a userspace extension. Now i face the problem that when i try to invoke iptable with the target i created i get an error message saying...

9. Programming

Problem in registering new netfilter target module

Friends I'm facing a big problem trying to extend the netfilter. Somone please help me with your quick reply (any hint) as I've to meet a deadline. My problem is that I've written a new netfilter target module and its corresponding userspace program for iptables to change the packet type of a...

10. Programming

Help in extending netfilter

Hi everybody, I have to write a module for matching in netfilter , extending the netfilter but I'm facing some problems can somebody guide me in that. I know that I need to write matching module working in kernel space and a program in userspace. I went through the HOWTO on netfilter-hacking but...

LEARN ABOUT ULTRIX

trace

trace(1) General Commands Manual trace(1)

Name
trace - trace system calls of programs

Syntax
trace [options] cmd args...

Description
The command with no flag arguments traces for the given cmd and args all system calls made and prints a time stamp, the PID, call and/or
return values and arguments and puts its output in the file trace.dump.

Options
-f filename
Puts dump in file filename.

-z Echos arguments only.

Only one of the following option arguments can be specified at one time.

-c# Traces given PIDs and their children. Up to sixteen PIDs can be specified.

-g# Traces given groups only. Up to sixteen Group IDs can be specified.

-p# Traces given PIDs only. Up to sixteen PIDs can be specified.

-s# Traces given system calls only. Up to sixteen PIDs can be specified.

-u# Traces given UIDs only. Up to sixteen PIDs can be specified.

Examples
trace -f ls.dump ls -l /dev >ls.out
runs the cmd ls -l /dev and puts the trace in ls.dump and output in ls.out.
trace -f csh.trace -p $$ &
will trace your login shell in the background. To stop the trace just send it a termination signal (that is, kill -TERM trace_pid).

Restrictions
Due to security, no one, not even the super-user can trace anyone else's programs. This sort of negates some of the usefulness of the -g
and -u flags.

The program cannot be traced.

Only 16 numbers can be given to the -c, -p, -g, -u, and -s flags.

The kernel configuration file must contain the following:
options SYS_TRACE
pseudo-device sys_trace

In addition, the superuser must use the following command sequence to create the device:
cd /dev
MAKEDEV trace
If both lines are not in the configuration file or if the device is not made, the message "Cannot open /dev/trace" appears.

Files
/dev/trace read only character special device for reading syscall data.

trace.dump default file for the system call trace data.

See Also
open(2), close(2), ioctl(2), select(2), read(2), trace(5)

trace(1)

IP Networking