Security :: Updates: Specify Source Port For Traffic?
Dec 14, 2010
I've a server, and I want to drop all the traffic going out with other source port than 80 (apache) and 22(ssh). The reason is I want to prevent my machine sending packets I don't know (i.e. my server scanning networks or making DDOS attacks without my knowledge). The problem are the updates. If I do what I've said, the updates will not work. I want to allow updates, so I need to let DNS traffic (port 53) and the traffic of the updates to go out.
The problem is the source port. This traffic uses a dynamic port (I think like HTTP). Is there any way to specify a source port to do this? If a have a static port to do this, I would drop all the traffic going out with other port than 22,53,80 and this port.
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Feb 1, 2011
I'm simply trying to make a little restriction on www packets under two rules:
1. Allow inbound/outbound www packets (works!)
2. DROP inbound traffic to port 80 from source ports less than 1024. (DOES NOT WORK!)
Now, technically, when i use hping to test my rules, hping3 192.168.100.100 -S -p80 -s 1023 I should NOT receive any packets. However, i still receive packets, which means my rule that says less than 1024 does not work. (see below)
And this is my iptables rules in shell-script so far:
#!/bin/sh
DEFAULT_NIC=eth0
SERVER_IP="192.168.100.100"
ALLOWED_WWW_PORT=80
IPT="/sbin/iptables"
[Code].....
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Apr 18, 2011
Is there any way to verify if packets being trafficked over a certain port are valid for the service you want to use this port for?
One obvious example that probably clarifies my question:
When I open port 443 (outgoing or incoming) for https/ssl traffic, I don't want this port to be used for say openvpn traffic.
Thus: when someone wants to surf to a website with https, it should be ok but if someone wants to connect to his home openvpn server over that same port, it should be blocked.
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May 3, 2011
I'm currently using a homemade Python script to parse script kiddie IP addresses from logfiles.To this point, I've simply been DROPping any requests from these IPs using iptables.I thought it might be fun to redirect their traffic back to them, but as I am not an expert at iptables, I was wondering if I should use FORWARD or PREROUTING.
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May 5, 2010
I have a question, on my firewall at work I am seeing a constant flow of denies from many different source IP addresses, of tcp/udp destination port 53372 & 53375.What in the world is that, and why these two ports over and over
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Jan 20, 2010
Does anyone knows of any open source proxy/web traffic monitoring application so I can run reports on users web browsing for Linux? Something equivalent to websense? but free I'm not really concern about blocking any traffic only running reports.
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Oct 13, 2010
I've got a Slackware 12.2 system that I'm trying to get to accept traffic on a given port, let's say 34521. When I use canyouseeme.org, to see if that port is responding, it is not.
I've put in an iptables entry to accept traffic on that port, is there anything else I need to do?
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Feb 2, 2010
I have "Server A" with real internet ip 1.2.3.4 (eth0) and lan ip 192.168.1.1 (eth1) There's also "Server B" with lan ip 192.168.1.2 (eth0), I'm running an Apache Web server on "Server B", so I want to redirect all traffic from IP 1.2.3.4 port 80 (Server A) to 192.168.1.2 port 80 (Server B), using the following rule:
[Code]....
iptables -t nat -A PREROUTING -p tcp -d 1.2.3.4 --dport 80 -j DNAT --to 192.168.1.2:80 This actually works pretty good, from internet I can browse ttp://1.2.3.4 But the problem is that if I check the Apache logs, all incoming connections seems to come from 192.168.1.1 instead of showing the real source ip addresses (internet ip's) so this is screwing up all my web stats, I've been looking for hours and hours on how to make a transparent redirect, but can't find any info, I know there must be a way because my old WRT54G router which uses iptables could do it.
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Nov 8, 2010
I'm new to iptable configuration. I've set up a VPN using DD-WRT on my router and it works fine. However the VPN company does not allow port 25 traffic (in case of spammers) so now I can't get my emails sent out.
I'm guessing I can add some rules to my iptable so that all traffic except port 25 traffic can go out through the VPN tunnel. And hopefully, all port 25 traffic will go out through the normal Internet connection.code...
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Mar 5, 2010
made software which we can get network traffic Report of of Switches for Daily,monthly and yearly base , in MRTG we can configure as a switch so we can get particular switch Traffic but how can we get each port of traffic of a switch in MRTG
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May 24, 2009
I have problem with port based routing for local traffic. I can't use trick with iptables -t mangle, ip route table 1, ip rule fwmark table 1 because it works only with forwarded packets. I can't even use patch-o-matic because it's obsolete. And xtables-addons doesn't contain support for "-j ROUTE" yet.
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Apr 19, 2011
Is there a graphic tool that can monitor the traffic over a USB port?
ie like system monitor for network traffic but over a specific port?
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Mar 25, 2011
So, it is my understanding that Ubuntu's automatic updates do not install ANY updates that are not "important security updates." For example, it did not upgrade me to Firefox 4 automatically; I had to do it myself (Don't all new browser versions usually contain new security features/patches? Oh well...That is a separate question entirely).
ANYWAY, is there some way to get the latest stable versions of all of my open-source software automatically (or at least all at once, on command), instead of just security updates? It seems silly to have to install new versions for every program manually.
Also, related/side question: Now that I have installed Firefox 4 myself (via apt-get by adding the mozilla-stable PPA), will I stop getting security updates for Firefox through the standard Ubuntu update manager?
Actually, a really thorough explanation of the whole automatic update system (or a link to one) would be great too.
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Sep 27, 2009
Recently I notice that when I'm connected to an vpn server (pptpd) and I'm using it as a default gateway my download and upload speed decreases almost to the half of the usual speed. I made a test using iptables in order to count how much GRE packets are generated (except the real traffic itself) in that way:
Code:
iptables -I INPUT -p gre -j ACCEPT
iptables -I OUTPUT -p gre -j ACCEPT
iptables -I FORWARD -s 172.16.10.101 -j ACCEPT
iptables -I FORWARD -d 172.16.10.101 -j ACCEPT
The first 2 rules match all GRE packets between the pptpd server and client, and the next rules - the traffic between the server and the client.
When I turn the counters to zero and begin to generate traffic (to browse, to download etc.) I see that the GRE packets are even more than these in the FORWARD chain.
So, my question is first of all is my test correct and is it true that so much gre traffic is being generated during the browsing (it becames clear that the traffic is double than if the pptpd wasn't used as a gateway) and if yes - can that traffic be reduced?
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Jul 1, 2010
I am trying to list all traffic from 1 IP address but filter out port 1057.I keep getting syntax errors. I've tried:
Code:
ngrep -e host xx.xx.xxx.170 not port 1057
ngrep -e port 1057 -x host xx.xx.xxx.170
ngrep -e not port 1057 -x host xx.xx.xxx.170
etc.
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Nov 1, 2010
sudo ssh -L 750:192.168.123.103:873 username@192.168.123.103It does exactly what it's supposed to do, but how do i edit / remove this rule?Is there some config file where i can alter the forwarding? How does it get stored?Im using Ubuntu 10.10Server Edition (allthough i recon it would be pretty much the same across all versions
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Apr 27, 2011
I'll explain this in one sentence: Is it possible to program a port-binding shellcode in which people across the Internet can connect to, without being thwarted by the router blocking their data because the port its bound to doesn't allow port-forwarding
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Jun 1, 2010
Im running a web server on port80, but i want traffic coming from ip 212.333.111.222 on port 80 to be fowarded to port 9020 on the same server that my web server is rinning at that is my sshd port
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Dec 5, 2010
I have set up an openvpn server on ubuntu via port tcp 443. The server use a public network and almost every ports are blocked (not 443) So when a client connect to the server, if it send traffic needing a blocked port, the connection cannot been etablished of course. So i d like to know if it is possible to redirect all incoming traffic on the server to an other unblocked port (like 443) to bypass firewall.
I dont think openvpn offer this possibility but maybe with linux it is possible..
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Sep 2, 2010
I'm running ASSP on Ubuntu 10.04.1 it's mostly working fine. I have one problem which has been bugging me for some time. I don't want to filter outbound mail, but if I can relay (proxy) my outbound mail through ASSP, then it can automatically add to the whitelist.
As ASSP is a proxy, I need a server to send it to once ASSP receives it. I've tried my ISP, but this failed and they weren't willing to confirm if a connection attempt was received at their end.
Current setup
Inbound
mx -> router -> ASSP -> Exchange 2003
Outbound
Exchange 2003 -> mx
I'd like to setup outbound as either
Exchange 2003 -> ASSP -> <ISP> SMTP relay
Exchange 2003 -> ASSP -> <relay running on Ubuntu eg postfix>
Can anyone help me with troubleshooting steps or a better suggestion for how I can set this up. I'd love to know why my ISP setup didn't work, but I don't know a tool for monitoring IP traffic in Ubuntu SE, in windows I use Wireshark is there any equivalent I can setup for Ubuntu or a tool I can use in windows which will show all traffic, Ubuntu and windows server are on the same netgear switch, not sure it's smart enough to copy all traffic to another port for monitoring.
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Apr 2, 2010
So yesterday I receive a copy of the SANS @RISK security vulnerability newsletter, and, lo and behold, Mozilla's Firefox and Thunderbird are on it yet again. (Yeah, I know, shocking, isn't it?)So I quickly check what versions I have installed. Yup: Vulnerable.I check whether updates are available.These are pretty serious "remote code execution" vulnerabilities and the status is "vendor confirmed, updates available." So why isn't my 9.10 desktop's update manager telling me updates are available?
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Aug 14, 2010
I'm new to server admin, so my question is based on what may be a bad assumption. With a server, my assumption is "if it ain't broke, don't fix it". In other words, I'm not really interested in upgrading the software to the latest and greatest if I already have stuff working on the server.
However, the one place where I DO want to constantly have upgrades is for security patches. How do I apply security updates to Ubuntu Server... and ONLY security updates?
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Oct 25, 2010
With an Ubuntu 10.10 upgraded from 10.04, under Software Sources, Updates, there is a radio button marked "Install security updates without confirmation." I have this radio button marked, but still get "Important security updates" almost daily in my update manager. I don't remember this feature actually ever working.
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Aug 25, 2010
Is there a way to to check if the system has the available security updates installed? Specifically, I am looking to do this programmatically.
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Jun 13, 2010
what rules I need to use to only allow traffic between 2 interfaces (which are part of a linux bridge) using ebtables?
So let's say I have if0, if1, if2. I want if1 to communicate with if0. I also want if2 to be able to communicate with if0. But I don't want if1 and if2 to communicate with each other.
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Apr 14, 2009
If I want to get updates I must use or whatever primary mirror closest to me?
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Jun 24, 2010
We use a squid proxy server for all http traffic. Is there any way to configure squid so that all traffic which squid and workstation communicates is SSL and encrypted ?
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Apr 26, 2010
Where I work we have a lan, it is almost 100% windows machines except for 2 CentOS machines in which some clients connect to, via VPN. (very small network, <50 ip's used)
I would like to know if there is a way to block access from that machines to others in the network. I'm already logging traffic (with IPTraff) to see if they're accessing other machines in the network others than the ones they should connect.
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Mar 11, 2011
has my Ubuntu machine been cracked?
machine on home lan
192.168.0.102
it is the DMZ from router
ufw on (ports open for aMule)
sshd installed
[Code].....
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Nov 11, 2010
As it stands I have a small home network operating behind my modem/router. Some of the ports on this are forwarded to my PS3 for gaming but I was looking at forward some for my file server.
At the moment I've forwarded port xxx22 to port 22 on my server for SSH for instance. ANd similarly 21 for FTP (although it doesnt seem to want to connect for any more than a few seconds using that). What I was thinking of doing was placing a small website for a handful of ppl to use on the server too and port forward again - xxx80 to 80. It works just fine but I'm a little concerned on the security front.
As I've moved the port to something different from the outside world I'm presuming I will have already cut the potential for malicious folks to wander in but is there anything else I should be doing? At the moment there's no firewall operating on the server, usually as its hidden behind the modem/router. But if I open this thign up more permanently what should I be doing? I've read a few articles on it but I'm always left with the overwhelming thought of "Thats if theres no firewall in my router" as they just seem to do the same.
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