Free tcp connections software for linux

HTTPTunnel is a simple client/server application for creating an HTTP tunnel between two machines, optionally via a Web proxy.
This is a small application for tunnelling an arbitrary TCP socket connection over HTTP. It can be used, for example, to tunnel traffic out from behind a restrictive firewall that only allows outgoing HTTP web connections.
The basic idea is that you run an instance of the HTTP Tunnel application locally in client mode, that then connects out to another instance that you run at the remote end of the tunnel in server mode.
You then connect to the local client end of the tunnel with the application whose traffic you wish to tunnel, and all communications are then wrapped in HTTP. The tunnel may also go via a HTTP proxy, either explicitly or transparently.
Enhancements:
- This release includes some major bugfixes and improvements in the tunneling error detection and retransmission code.
- It also introduces support for building and running under Cygwin.

jail (Just Another IP Logger) is a simple, but often useful network security tool which displays ICMP packets and attempted TCP connections from remote hosts.

The application features better configuration and logging options than the iplogger package it was written to replace.

icmplog and tcplog can either ignore any packet, or log it at any of the
syslog levels (as defined in < syslog.h >). The log level is configurable
depending on the ICMP type (icmplog) or the port on which a connection is
requested (tcplog). The default facility (LOG_DAEMON) for logging messages
can also be changed in the configurations files.

The level at which a given type of packet is logged is specified in the
configuration files (/etc/icmplog.conf and /etc/tcplog.conf by default,
which can be overriden with the --file option). You can also specify
a default level, which matches packets that have an unknown or unconfigured
type. See the example configurations included and the icmplog(8) and
tcplog(8) manual pages for more information.

Log entries contain the source and type (icmplog) or destination port
(tcplog) of the received packet. If a packet is of an unknown type, its
numeric value is logged instead of its name. The source is logged
either as a hostname or as an IP address (see the -n option). Typical
entries look like:

Jun 16 17:47:30 lustre icmplog: started
Jun 16 17:47:31 lustre tcplog: started
Jun 16 18:54:14 lustre icmplog: time exceeded from sunsite.unc.edu
Jun 16 18:56:14 lustre tcplog: port 1039 request from ftp.cs.umn.edu
Jun 16 19:47:24 lustre icmplog: destination unreachable from 209.39.121.4

The INSTALL file contains detailed installation instructions. Read the
icmplog(8), icmplog.conf(5), tcplog(8) and tcplog.conf(5) manual pages, and
the example configuration files (icmplog.conf and tcplog.conf) for
more information on setting up and using jail.

jail was originally based on the iplogger package, but offers greater
configurability and better options. It bears very little resemblance to
the original program now.

jail is distributed under the Artistic License (a copy of which is included
in the distribution) and comes with no warranty, express or implied. If it
breaks...well, keep the pieces.

Samhain is a multiplatform, open source solution for centralized file integrity checking / host-based intrusion detection on POSIX systems (Unix, Linux, Cygwin/Windows).
samhain project has been designed to monitor multiple hosts with potentially different operating systems from a central location, although it can also be used as standalone application on a single host.
Main features:
Centralized monitoring
- Samhain clients (or agents) can connect to a central log server via secure (encrypted and authenticated) TCP connections. This allows central logging to the server, central storage of baseline databases and client configuration data, and central updates of baseline databases.
Web-based management console
- For client/server installations, a web-based console - Beltane - is available as separate package. Beltane allows to monitor server and client activity, view client reports, and update the baseline databases on the server side.
Multiple logging facilities
- Samhain supports multiple logging facilities, each of which can be configured individually. Supported logging facilities include (but are not limited to) tamper-resistant logfile, syslog, email, relational databases (MySQL, PostgreSQL, Oracle, or unixODBC) and the Prelude IDS.
Tamper resistance
- Samhain offers PGP-signed database and configuration files, a stealth mode, and several more features to protect against attempts to subvert the integrity of the samhain client / agent.
Enhancements:
- This release fixes some minor bugs.
- The portcheck module tears down connections for some common protocols more gracefully.

Fwctl is a Perl module to configure the Linux kernel packet filtering firewall.

SYNOPSIS

use Fwctl;

my $fwctl = new Fwctl( %opts );
$fwctl->dump_acct;
$fwctl->reset_fw;
$fwctl->configure;

Fwctl is a module to configure the Linux kernel packet filtering firewall using higher level abstraction than rules on input, output and forward chains. It supports masquerading and accounting as well.

Why Fwctl ? Well, say you are the kind of paranoid firewall administrator which likes his firewalls rules tight. Very tight. Say the kind, that likes to distinguish between a SYN and ACK packet when accepting a TCP connection (anybody configuring packet filters should care about that last point), or like to specify the interface name on each rules. (Whether this is really need, or such a stance is relevant, is not the point.) How would such an administrator proceed ? First of all you deny everything on all interfaces and on all chains (input, forward and output) and turn on logging. Now starting from this configuration (in which Fwctl puts the firewall on initialization), say you want to enable ping from the internal network to the internal ip. What rules do you need ? You need a rule on the input chain to accept the echo-request packet and a rule on the output chain to accept the echo-reply request. Right ? Well, what about the loopback. For sure, when we say from local net to local ip, this imply local ip to local ip ? Then you add a rule to the output chain with the loopback interface, and a rule on the input rule to the loopback chain. And we didnt even start forwarding yet ! Add masquerading to the lot and multi connections protocols like FTP and you got something unmanageable. So you start accepting things you shouldnt to get your job done and in the end your filters look like emmenthal.

Fwctl handles all the complexity of this, so that when you say

accept ftp -src FTP_PROXY -dst INTERNET -noport

you dont accept too much of what you didnt intend. (Well you just opened arbitrary TCP connections to unprivileged ports on the Internet from your proxy server, but thats because of the FTP protocol, not because your cheating on the firewall rules.)

Fwctl works with entity known as service. A service can be ftp, netbios, ping or anything else. The service abstraction handles all the communication necessary for that application. (The UDP and TCP communication in DNS, or the control, data and passive connections for FTP.)

Additionally, to handle all the special case with ANY specification, when the src of dst imply a local IP, or masquerading, in short for Fwctl to be able to deduce the interface implicated by the src and dst portion of a rules you need to provide it with your network topology. Fwctl must guess from your topology the routing decision that will be made in the kernel. In the best of worlds, Fwctl should contains the same routing algorithm as the one in the kernel. Well, it doesnt so if you are using fancy routing feature, Fwctl wont work. In fact, it can only handle something equivalent to simple static routing. You have been warned.

So in short, to configure your packet filters with Fwctl you need to
Define your network topology using the interfaces file.

(Optional) Define meaningful aliases for hosts and networks which are part of your configuration.

Implement your security policy using high level abstract rules in the rules file.
Finally, Fwctl is extensible. You can easily add services modules using the Fwctl::RuleSet module which contains all the primitive you need to handle all the special cases involved in the input, forward and output chain selection.

Gratissip Tftp is a program that displays TCP/IP connections on an LCD display.
ratissip Tftpd is a TFTP server written in Java. It has special extensions which allows it to serve firmware and provisional settings for Grandstream VoIP phones.
Enhancements:
- The code was fixed up for announcement.

Net::Proxy is a Perl framework for proxying network connections in many ways.

SYNOPSIS

use Net::Proxy;

# proxy connections from localhost:6789 to remotehost:9876
# using standard TCP connections
my $proxy = Net::Proxy->new(
{ in => { type => tcp, port => 6789 },
out => { type => tcp, host => remotehost, port => 9876 },
}
);

# register the proxy object
$proxy->register();

# and you can setup multiple proxies

# and now proxy connections indefinitely
Net::Proxy->mainloop();

A Net::Proxy object represents a proxy that accepts connections and then relays the data transfered between the source and the destination.

The goal of this module is to abstract the different methods used to connect from the proxy to the destination.
A proxy is a program that transfer data across a network boundary between a client and a server. Net::Proxy introduces the concept of "connectors" (implemented as Net::Proxy::Connector subclasses), which abstract the server part (connected to the client) and the client part (connected to the server) of the proxy.

This architecture makes it easy to implement specific techniques to cross a given network boundary, possibly by using a proxy on one side of the network fence, and a reverse-proxy on the other side of the fence.

Leafnode is a software package that implements a store & forward NNTP proxy (client and server) that supports TCP connections across IPv4 and IPv6. Leafnode can be used to give a regular newsreader off-line functionality, merge news articles from several upstream newsservers for newsreaders that only support one server well and avoid duplicate news download for a small LAN with multiple users reading news.

Leafnode is intended for use at home or in small offices. Scalability for large user or newsgroup counts has not been a design goal.

Leafnode is easy to install, requires no maintenance and can run unattended. It will recover from most problems without user intervention if possible. No configuration of a newsfeed at the upstream server is necessary, leafnode looks to the upstream server like a regular newsreader program.

Leafnode will automatically figure which newsgroups are read locally and will download them, and it will stop downloading from these newsgroups if they havent been read locally.

It allows for simple filters to limit the number of articles downloaded, the size or exclude articles with particular headers (Perl-compatible regular expression match). It has a mode to optionally download only headers in a first run, lets the user mark these through his newsreader (note that not all newsreaders will work) and download the full article texts in the next run.

Leafnode works perfectly with most common newsreaders either via NNTP or with traditional spool access.

Leafnode is an Open-Source package and runs on Linux, FreeBSD, Solaris, and probably most Unix flavours.