Networking :: How Can We Make Port 110 And 25 Packets Pass?
Feb 22, 2011
I've a strange situation in my network: pcs gatewayed to another network, then a proxy, then a firewall.pcs --> router --> cloud --> router --> proxy --> switch <-- fw --> Internet(router, proxy and fw are alla connected by the switch)Some months ago the situation was: pcs --> router --> cloud --> router --> switch <-- fw --> Internet.There was a static route in the router that gatewayed the packets to the firewall, but that route has been deleted, and I cannot reinsert it because I've not access to the routers, so we have to use a proxy to go to Internet, and we have the configuration of all pcs (Windows XP) with the fields "proxy" filled.The proxy ha only one NIC gatewayed to the firewall, and Ubuntu and squid installed, but we have some problems:
1. we cannot use email, so how can we make port 110 and 25 packets pass?
2. squid seems to slow down, so can we uninstall it and route all the traffic directly to the firewall to speed up?
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Feb 8, 2010
i have a linux server runnig oracle applications. i need to access this server from putty using ssh through internet. i did by registering my static ip with the dnydns.org and i am able to connect to the server. but now there is no security to authenticate any user as any one knowing the password can login to it.
i thought of configuring the firewall of linux server but the client ip`s are not static and they change continiously. so thought of keeping one more pc between the server and the router which will do the work of authenticating. but i am confuse as how to configure it to allow the packets coming from the internet after authenticating and to by pass the packets generated from internal LAN?
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Apr 7, 2011
I have been working in Linux for the past two years.And working in squid for the past 6 months.The following is my Setup
ETH1 - ISP1 (Active)
ETH2 - LAN (Active)
ETH3 - ISP2 (Inactive)
Using Iptables I forward 80 port through squid (3128).Other ports just get connected in the proxy machine itself since it has IP_FORWARD enabled. All my client machines browsers enabled with "Use proxy 3128". I just want to make all the port to pass through squid server.
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Apr 4, 2011
I'm trying to use iptables in order to forward all the incoming packets for port 5555 to port 5556 on the same server (192.168.2.101).
I wrote the following commands:
iptables -A PREROUTING -t nat -i any -p tcp --dport 5555 -j DNAT --to 192.168.2.101:5556
iptables -A FORWARD -p tcp -m state --state NEW -d 192.168.2.101 --dport 5556 -j ACCEPT
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May 26, 2010
I'm running IPF on solaris 10 Note :i believe the idea will be the same it doesn't matter either its linux or solaris
Code:
bash-3.00# ipf -V #display ipf version
ipf: IP Filter: v4.1.9 (592)
[code]....
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Jun 13, 2010
I am currently having problems with my server. Its being DDOSed. I have a vps with Centos 64bit. The attack I want to block is udp flood. I was trying to do something like this: iptables -I INPUT -p udp --dport 123 -m limit --limit 40/s -j DROP but instead of blocking certain hosts it blocks the whole port and during the attack its unreachable. How to limit packets per host or any other way to protect from udp flood.
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Sep 6, 2010
We are trying to create a message forwarder program that receive a message on Port A and pass it on t Port B. Also receive a message from Port C and Pass it on to Port D as follows.
[Code]...
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Aug 30, 2010
i need to write a program in c that can sniff packets from Ethernet and distinguish RTP packets from Non-RTP packets, i have no idea what should i do
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Mar 16, 2011
This is where it starts: I have 2 networks. The first: 192.168.1.0/24 composed by the router which has access to the internet with the IP 192.168.1 and the server (who is a gateway) with the IP 192.168.1.42 The other network: 192.168.2.0/24 composed by the gateway with the IP 192.168.2.1 and the clients (on the 192.168.2.0/24 subnet). To sum up, the gateway has 2 IPs (192.168.1.4(eth0) and 192.168.2.1(eth1)). On this gateway, I have squid installed (and listening on port 3128). I also made a redirection to redirect some computers who want to access to the web (port 80) to squid (port 3128) with this command: /sbin/iptables -t nat -A PREROUTING -m mac --mac-source CLIENT_MAC -p tcp -m tcp --dport 80 -j REDIRECT --to-port 3128
At this stage, everything works fine. The clients can access the web by the proxy without "knowing". What I wanted to do, is redirect also the port 443 (HTTPS). Actually, when a client wants to access to, for example, [URL]. He cannot. So I would want to be able to redirect people (without passing by any proxy) directly to google. Like a NAT. But the problem is that I can't. The thing would be to, in the gateway, take all the packets with port 443 in destination and handle them to the router 192.168.1.1. Then, when the router sends the packet back, the gateway takes the packet and handles it to the client. I tried putting ip_forward to 1, but the problem is that all IPs and ALL PORTS are forwarded. And I just want port 443 to be forwarded.
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Jul 3, 2010
I'm trying to capture packets with WireShark on 2 port ranges.
This syntax is not working :
Quote:
bash-3.2# /usr/sbin/tcpdump -ttttvv udp portrange 8500-8600 and portrange 5060-5070
There is no output...
What is the correct syntax for defining multiple port ranges ??
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Jun 6, 2010
I was testing the security of my Ubuntu 10.04 64bit install by running a port scan from [URL] and I came upon some odd results. It appears that basically all my ports are closed, but only Port 646 is dropping packets silently. Furthermore, Port 80 is open.
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Jan 3, 2011
how can i drop igmp port 0 packets with iptables rule? my log file is full of this router advertisement.
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Sep 3, 2010
How do I change the ports that something like xchat uses to make it use the same port as firefox? I am currently somewhere that has all non browser ports blocked.
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Oct 17, 2010
I have a gateway server which is currently listening for TCP/UDP packets and authenticating clients if their details IP/MAC is known.
I have a couple of clients who's network equipment sends ICMP pings to a remote site to determine internet connectivity and I'm missing those resulting in the client's device not logging in.
Is there some way that I can write a listener similar to a listener for TCP/UDP sockets which will listen to ICMP packets and pick up the IP and MAC address of the sender upon which I can perform processing on?
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Feb 18, 2010
I want to do a simple port redirect, i.e. whatever comes trough whatever interface on port AAAA will get redirected to port BBBBI thought that iptables -t nat -I PREROUTING --source 0/0 --destination 0/0 -p tcp --dport AAAA -j REDIRECT --to-ports BBBBhowever it doesn't work, e.g. nc -v -w2 -z localhost AAAA gives:
nc: connect to localhost port AAAA (tcp) failed: Connection refused
while
nc -v -w2 -z localhost BBBB
[code]....
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Sep 27, 2010
I have a hardware device with two ethernet ports, eth0 and eth1 running Centos 5. Basically my goal is to forward packets from eth0->eth1 and eth1->eth0 as well as get a copy of these packets for analysis. If I set IP routing to do the forwarding then I won't get a copy of the packets for analysis.
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Jun 7, 2010
I'm trying to do a shell script which are suppose to run a program as a specific user at system boot up. The problem is that I don't know for sure how to make the script add the users password to the prompt when it's necessary.
Basically the program would be run like this:
sudo -u extrema program_name -r /srv/program_name -d
and in this example the password is, "hidden".
How would I make this script run this program as user extrema with the password "hidden" at boot-up? I know how to put the script in the rc.X directory and so on, its more the syntax of the code.
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Apr 1, 2011
I want to pass ip address,port address and some parameters from command line using python script.The ip address and port address for establishing socket connection and remaining parameters to execute different connection.
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Aug 7, 2010
When I use the following command:
ssh user@ssh_server -L 5500:localhost:5500 -p 22
everything works fine. I can log in, and local port forwarding is done. Otherwise when I use the command:
ssh user@ssh_server -R 5500:localhost:5500 -p 22
I get an error "remote port forwarding failed for listen port 5500". However when I try remote port forwarding in WinXP by use of putty there is no problem...
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Mar 17, 2011
I am wanting to make traffic pass through my computer to another computer.
Here is my current network setup:
[WAN] > [MODEM] > [10.1.1.3] > [192.168.56.101]
How can I make my computer ([10.1.1.3]) forward incoming traffic on port 25 to [192.168.56.101]?
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Feb 20, 2010
I'm using a Debian servers, as router/firwall.. I've two ethernet interfaces into the server, one for wan and one for lan. The i use SNAT so my LAN clients can access the internet throgh the debian router. That is working... Now i want to be able to access servers on the LAN site from the WAN site, and i wanna use port address translation (PAT). I have a FTP server running on a lan server, so i'm trying to portward port 21.
iptables -t nat -A PREROUTING -p tcp -i eth1 -d (WANIP) --dport 21 -j DNAT --to 192.168.1.2:21
When people try to access my FTP from the WAN site, they are redirected to the local FTP server, and they are promted for crendentials, but when the credentials are typed, and the local ftp server should answer the wan request, the connections dies.
The wan clients are being promted for credentials, so they are redirected to the local lan server, but after that the connections dies, so i think there is some kind of nat problem, when the local lan server is trying to respond to the wan request..
Here i my iptables script:
#flush table
iptables -F
#input regler
[code]....
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Feb 12, 2009
I make an application on GNU/Linux which listening on a MULTICAST stream, so I open my unconnected socket, bind it on a MULTICAST address and a port, join the multicast group with the "setsockopt (IP_ADD_MEMBERSHIP)", then I receive datagram on my socket.
Now I've two different instances of the same application that run with their own MULTICAST address and port. And what I found strange is that, after a misconfiguration, I switch the ports, for example:
Emitting on 225.0.0.1/23451 and 225.0.0.2/23452
Receiving on 225.0.0.1/23452 and 225.0.0.2/23451
And my receiving part doesn't care about the MULTICAST address, it looks like the socket is listening on the port number only! I mean that the receiver [225.0.0.1/23452] take its datagrams from emitter [225.0.0.2/23452] and vice-versa!
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Jul 14, 2011
I want to set my ip as static and port forward it through a specific port can anyone help me with this im using ubuntu 10 with 64 bit OS
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Apr 25, 2009
How can i redirect data received on a port to another port located in a different machine? Can i do this using IPTABLES ?
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Mar 25, 2010
I have a mail server on which I would like to block port 25 on my eth0 for everyone except our external spam filter. the problem is that I want our users to be able to connect via port 10025 which is forwarded to port 25, which then is blocked...
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Oct 24, 2010
I had to add them to my firewall script when I installed openvpn on my dd-wrt router:
iptables -I FORWARD -i br0 -o tun0 -j ACCEPT
iptables -I FORWARD -i tun0 -o br0 -j ACCEPT
iptables -I INPUT -i tun0 -j REJECT
iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE
what should I add/change to set up port forwarding of port 1000 to ip 192.168.1.200. also how to get the answer sent by 192.168.1.200 follow the same route used by the data received through port forwarding.
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Sep 6, 2010
My setup is...I have a wireless access point using laptop as a gateway. The AP is also connected to a switch as is the laptop. So the laptop has two interfaces one wireless and one wired. A third device is using the AP to connect to a server on the internet. The AP sends the packets to my laptop where they are dropped. I've been looking for a solution to this problem without success. Basically is there a way for my laptop to forward all packets it sees from a certain IP address to whatever destination address they have?To clarify, my laptop is just the gateway of the AP and none of the packets are addressed to it at all, it just picks them up using a sniffer or similar tool.
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Dec 3, 2010
using layer 7 filtering how to block the ftp packets?..
In My router i am going to add a below rule.... iptables -A OUTPUT -m layer7 --l7proto tcp --dport 20 -j DROP
above statement will it work in my router?.
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Oct 17, 2010
1) i have to find the source and destination address in the ip and ethernet headers of a packet that go from my machine to the router.2) Then i have to do the same for the packet that goes from the router to my partner's machine.Then I have to answer the above questions but now for the echo replay.How could i see these address?The result could be found in the output of a tcpdump?
[guest@shakti guest]$ sudo tcpdump -en host 128.238.62.101 and 128.238.61.101
tcpdump: listening on eth0
20:27:36.662737 0:4:75:b5:20:bc 0:3:e3:2a:4a:60 ip 42: 128.238.61.101 > 128.238.62.101: icmp: echo request
[code]....
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Feb 15, 2010
I've a ssh server on FEDORA 12. It was going well but now it's overloaded with ARP traffic and is unable to run ssh. normally i'm getting about 150 packets in just 3 second
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