03-22-2004
All applications can talk through a firewall as the firewall is just a configurable piece of hardware or software that allows or disallows network communication based on a set of rules. The firewall is transparent to the application and the underlying socket routines used just as the many routers and switches in between the two machines are transparent. This is the nature of IP packet routing.
However, if what you are talking about is attempting to get your application's communication "through" the firewall you may want to research such things as SOCKS. Many applications can use these "proxy servers" to tunnel through a firewall by authenticating their communication through it. If this is what you want then google SOCKS and I'm sure you'll find out a lot more than can be explained here.
10 More Discussions You Might Find Interesting
1. HP-UX
Our system is having a server and multiple clients. We are monitoring the client FDs using select() system call in HP-UX.
After establishing connection-using socket with the remote client, before start sending the data we are checking the status of socket using select( ) call. For first 16... (0 Replies)
Discussion started by: AshokG
0 Replies
2. Programming
Can anyone help? I'm trying to write a program which will write to a socket. I can get the server to run, but always get an error when I try to connect.
It gives me an error at the "connect" command.
It's probably a simple error, but I can't seem to find it.
#include <sys/socket.h>... (6 Replies)
Discussion started by: Stevhp
6 Replies
3. UNIX for Advanced & Expert Users
I am not able to receive the message on socket in the current process when its waiting for its child to exit.
code looks something like below
//in one thread of the current process
//thread 1
===============================================
int numBytes = read(sockid,buf,SIZE); //Now the... (2 Replies)
Discussion started by: swap007
2 Replies
4. Programming
Dear All,
I've searched many topics and googled many web-pages, but still I didn't found solution to this problem.
I want to set timeout for connect(). The thing is, that my code works only on BSD, on Linux (tested on SuSE box) it freezes at connect() call :(
bool
SomeFunc(std::string... (1 Reply)
Discussion started by: sggkxv
1 Replies
5. UNIX for Advanced & Expert Users
Hi,
I was porting ipv4 application to ipv6; i was done with TCP transports. Now i am facing problem with SCTp transport at runtime.
To test SCTP transport I am using following server and client socket programs. Server program runs fine, but client program fails giving Invalid Arguments for... (0 Replies)
Discussion started by: chandrutiptur
0 Replies
6. Programming
I have a client /server file operation program.It works properly when i run the client and server program in the same system.but when i try to run the client in one system and server in another system i am getting an error in the cleint machine as "ERROR:Connection refused". Plz help me in this
... (1 Reply)
Discussion started by: vigneshinbox
1 Replies
7. Programming
I wrote a program which will send a message to multiple clients(i.e, broadcasting) that are connected to a server.Once when the client receives a message from the server ,the client should read a file in the server and display it in the client.The client which responds (i.e, client wants all the... (3 Replies)
Discussion started by: vigneshinbox
3 Replies
8. Programming
Hi,
My name is Daniel and I'm spanish, so I'm sorry if you can't undertand something becouse of my low-level english.
Something stranger is happening to me with socket++ library and I don't know how to work on it.
I has a library called commands.so and the sslclient is and object of that... (4 Replies)
Discussion started by: lock.cda
4 Replies
9. Post Here to Contact Site Administrators and Moderators
hi,
i am new to socket programming.i have a problem in server.requirement is it should continuosly read the requests from client(sends requests continuously) and after certain delay(i kept der sleep) should send response.
for this i used msgqueues so that after reading it is sending into... (1 Reply)
Discussion started by: chandinisree
1 Replies
10. IP Networking
Hi
My socket program is to communicate between the two systems connected with lan. Always i am getting an error saying bind value is -1 or not connected. ..If i run both the server and client programs in the same machine in two diff terminals they are working but they are not working between two... (3 Replies)
Discussion started by: Gurvareddy
3 Replies
LEARN ABOUT CENTOS
socks_clients
SOCKS_CLIENTS(1) General Commands Manual SOCKS_CLIENTS(1)
NAME
rfinger - SOCKS client version of finger
rftp - SOCKS client version of ftp
rtelnet - SOCKS client version of telnet
rwhois - SOCKS client version of whois
SYNOPSIS
See the man pages on finger(1), ftp(1), telnet(1), whois(1).
DESCRIPTION
These programs provide the well-known functionalities to hosts within a firewall. Normally, when a firewall is constructed, IP-accessibil-
ity across the firewall is cut off to reduce security risk to hosts within the firewall. As a result, inside hosts can no longer use many
of the well-known tools directly to access the resources outside the firewall.
These programs restore the convenience of the well-known tools while maintaining the security requirement. Though the programs differ very
much from their counterparts in the use of the communication scheme, they should behave almost indistinguishable to the users. Note though
that rftp does echo the password as you type it in if you are using anonymous as log-in name. Unlike those of the previous versions, these
are "versatile" clients, meaning that they can be used for connections to inside hosts directly and to outside hosts via SOCKS proxy
servers. So they can be used as replacements of their traditional counterparts.
When any of these programs starts, if the environment variable SOCKS_BANNER is defined, the program prints to stderr its version number and
the name or IP address of its default SOCKS proxy server. It then consults the configuration file to determine whether a request should be
allowed or denied based on the requesting user, the destination host, and the requested service. For allowable requests, the configuration
file also dictates whether direct or proxy connection should be used to the given destination, and optionally the actual SOCKS servers to
use for the proxy connection. The program lookps first for the frozen configuration file /etc/socks.fc first. If that's not found, it then
looks for the file /etc/socks.conf. If both files are absent, these programs will only try direct connections to the destination hosts,
making them behaving like their regular counterparts.
You can use environment variable SOCKS_NS to set the nameserver for domainname resolutions. Be sure you use the IP address of the name-
server you want to use, not its domainname. If SOCKS_NS doesn't exist, the IP address defined by the symbol SOCKS_DEFAULT_NS at compile
time is used if the programs were compiled with that symbol defined. Otherwise the nameservers specified in /etc/resolv.conf are used.
All the client programs uses syslog with facility daemon and level notice to log their activities. These log lines usually appear in file
/var/adm/messages though that can be changed by modifying /etc/syslog.conf. (See syslogd(8) and syslog.conf(5).) Typical lines look like
Apr 11 10:02:23 eon rfinger[631]: connect() from don(don) to abc.com (finger) using sockd at socksserv
May 10 08:39:07 eon rftp[603]: connect() directly from blue(blue) to xyz.edu (ftp)
May 10 08:39:09 eon rftp[603]: bind() directly from blue(blue) for xyz.edu (ftp)
May 18 13:31:19 eon rtelnet[830]: connect() from root(jon) to xyz.edu (telnet) using sockd at sockd2
May 18 14:51:19 eon rtelnet[921]: refused -- connect() from jon(jon) to xyz.edu (telnet)
Of the two user-ids appearing in each log line, the first is the effective user-id when the program is invoked, the second (that within the
parentheses) is the one used at login. Access control applies to the effective user-ids.
SEE ALSO
finger(1), ftp(1), sockd(8), sockd.conf(5), socks.conf(5), telnet(1), whois(1)
ENVIRONMENT
SOCKS_SERVER, if defined, specifies the name or IP address of the SOCKS proxy server host to use, overriding the default server compiled
into the programs.
SOCKS_NS, if defined, specify the IP address of the domain nameserver that should be used for name resolution, overriding both the defini-
tion of symbol SOCKS_DEFAULT_NS and the file /etc/resolv.conf.
ORIG_FINGER, if defined, specified the (altered) full pathname of the original finger program, which should have been renamed before
installing the rfinger as the regular finger. The rfinger program invokes the original finger program to lookup information on local users.
Normally this name should be compiled directly into rfinger, avoiding the need for this environment variable. Use ORIG_FINGER only if you
want to override what is compiled into rfinger.
AUTHOR
David Koblas, koblas@netcom.com
Ying-Da Lee, ylee@syl.dl.nec.com
May 6, 1996 SOCKS_CLIENTS(1)