I am at a large University, with servers set up on the Univeristy network. The network has internal (10...) IP addresses, and external (129...) IP addresses. I have a ColdFusion-based business process which FTP's data from an external server.
The server on which the ColdFusion instance is based has several (about 10) IP addresses associated with it, both internal and external. It has one primary address, which has been, until recently, external.
Using Wireshark, we have been able see which IP is used, and it is never the primary, but other than that, does not seem to follow any logic.
We recently changed the primary IP for the server to an internal address, to comply with new University-wide security policies, and the FTP connection from Coldfusion stopped working. Using Wireshark, we've confirmed it is going out on one of the internal (10...*) IP addresses (not the primary).
Is there a way to control which IP ColdFusion uses for an FTP connection, either through system configuration, or programmatically?
Code for the FTP call:
var ftpService= new ftp(
username = partnerConfig.sftpLogin,
connection = "MyConnection",
password = partnerConfig.sftpPw,
fingerprint = partnerConfig.sftpFingerprint,
server = partnerConfig.sftpServer,
secure = "yes"
);
var result=ftpService.open();
var result2=ftpService.listdir(directory = partnerConfig.inFolder, name="dirlist");
var result3=result2.getResult();
EDIT: My server guy tells me that this University is fairly unique in how it configures the subnets. NO firewall exceptions are allowed from the 10.* subnet. The "Public" IP's are not public by default, simply the ones which are capable of having exceptions.
FURTHER EXPLANATION: It comes down to the Rules and IP addresses the main IT org at the university set up. the 10.x.x.x IPs are never allowed access outside the university ("internal"). 129.x.x.x IP, may have firewall exceptions ("external"). If I type ipconfig (it's Windows), I see about 10 static IP addresses, half of which are 10.x.x.x, and half of which are 129.x.x.x. When the "primary" IP for the machine was a 129.x.x.x address, Coldfusion chose one of the OTHER 129.x.x.x addresses for the outgoing IP for the connection. With the "primary" IP switched to a 10.x.x.x IP, ColdFusion is choosing one of the OTHER 10.x.x.x addresses for the outgoing connection. My choices, as far as I can tell are 1) Switch the primary back to a 129.x.x.x for the server; 2) Move the site to a different server with a primary of 129.x.x.x, and keep other sites on the server in compliance with the new policy; 3)See if I can figure out how to control which IP Coldfusion chooses from the 10 static IPs on the server.
Our admin figured it out. We needed to add a static route to the server, so that whenever ColdFusion (or any application) tries to connect to the specific destination we were FTPing to, it goes through a specific outgoing IP address.
This was not something I was familiar with, but a quick search gives the basics: http://technet.microsoft.com/en-us/library/dd469825.aspx
You have an internal IP address and you are not sure what the external is? This sound like a network bridge issue. What you are looking for is FTP proxy or some tool that associates an externally assigned IP to an internally assigned IP for port 22 (or whatever you set your port to). Look at: http://wiki.squid-cache.org/Features/FtpGateway
FTP reverse proxy
It sounds like your IPs (even internally may not be static)...or maybe it just feels that way. Make sure your internal IP is static.
Read about FTP port forwarding: Here are some port forwarding guides.
Other keywords FTP bridge, FTP one-to-one mapping, among others.
Good luck.
I had a similar question regarding the cfmail tag:
Force cfmail tag to send from a specfic server IP address
Unfortunately, I didn't get an answer that worked. ColdFusion seems to pick (seemingly at random) which source IP address is used.
Related
I am struggeling to connect to my home server that is connected via a Fritzbox router to the internet. I want to connect to the home server from outside of the home net, as it serves as a NAS and provides HTTP(S) services.
The problem is, that I don't understand how to connect to the server over the internet. My Fritzbox is connected to my internet provider via DS-Lite internet connection. As far as I understood, this means that my Fritzbox has no public IPv4 address and therefore the server is not reachable.
Is it still somehow possible to connect to the server?
Reading your question, I can see that there are multiple steps to solve this.
figure out if your internet provider allows you to have incoming connections
I do not know, what a ds lite connection is. Depending on your connection type, e.g. glass fibre, dsl, mobile and your provider incoming connections might be allowed or not. Also specific ports might be forbidden.
Enable port forwarding for incoming connections to your lan server.
Your fritzbox does not know, where to route the incoming connection to.
Make your lan server ip address static. Go to your fritzbox admin page and create a port forwarding rule and map data incoming on port 80(HTTP) and 443(HTTPS) to the lan server ip address.
You can read further here: https://en.wikipedia.org/wiki/Port_forwarding
Figure out the fritzbox's public ip address by checking out this website from within your lan. https://whatismyipaddress.com/
Connect to your server via http(s)://publicip
setup dynamic dns to have a public domain, which you can use instead of the ip address.
Usually private customer internet connections use dynamic ip addresses. So your ip address changes regularly. This is annoying, because you need to lookup the ip address before you can connect again. To avoid this issue, you can use a dynamic dns provider to give you a domain name, which you can use instead of the public ip address. Your fritzbox should have this kind of functionality already. If not, you can also configure it on your server with a cron job.
You can read further here: https://en.wikipedia.org/wiki/Dynamic_DNS
This provider is easy to use and for free: https://freedns.afraid.org/
use the dynamic dns domain name instead othe public to access your server from anywhere
Be aware, that having open connections to your local network gives attack surface from the public internet. So people might steal or delete data on your server or abuse it in other ways.
I am trying to get the big picture although my primary domain is not networking.
Some question's narrowed down for which I'm not getting enough/proper answers online
Is the IP that is resolved by the DNS server when I hit www.google.com is same as any of the Google router's Gateway IP?
Do bigger companies like Amazon do port forwarding?
If point 2 is true, I suppose they must be port forwarding with only 443 (https) port which means, to use multiple static IP across different data centers, they need to have that many routers. So, if they have N static IP address which resolves to a website, then they must be having N routers right? Is this a fair assumption?
A gateway IP refers to a device on a network which sends local
network traffic to other networks. it sits between you and internet,or other network . its like a watchman.
Question 1 : google.com has multiple ip addresses lets say then , Yes, that is possible, and will need to be two A records. This is called Round-Robin DNS. Clients will semi-randomly use one of the two addresses.
question2: yes port forwarding happens more often than we think. ALL VPC's (virtual private clouds like AWS , GCP , Azure etc) use this as they dont want to expose servers/internal resources to the internet.
depending on the port number , particular service is exposed to requesting client. lets say we want to make a website public , then we explicitly expose port 80(http) 443(https) so that web crawlers and users can see them.
Port forwarding, sometimes called port mapping, allows computers or
services in private networks to connect over the internet with other
public or private computers or services.
google https://www.google.com:444/ wont work because they did not expose port 444 on their cloud router
but https://www.google.com:443/ will work because the server corresponding to google.com has explicitly left it open.
How IP is resolved:
Step 1 - Send a Request to Resolve a Domain Name
When you type www.google.com into a browser, in order to load the webpage, your computer asks for the IP address. Computers do not know in advance where they can find the necessary information, so they try searching through the DNS cache and for available external source. proceed from lower level caches to root/main servers.
Step 2+3 - Try to resolve an IP Locally
Before going externally, your computer loads the local DNS cache database to see if you already requested the IP for that domain name. Every computer has a temporary cache with the most recent DNS requests and attempts to connect to online sources. if required record is present locally its called "CACHE HIT" and query stops.
However A computer’s local DNS cache database does not always contain the necessary data to resolve a domain name this is called a "CACHE MISS" . In that case, the request goes further to your Internet Service Provider (ISP) and its DNS server.
Step 4 - ISPs Ask Outside DNS Servers to Provide an IP Address iff Cache miss
ISP DNS resolvers are configured to ask other DNS servers for correct IP address mapping until they can provide data back to the requester. These are iterative DNS queries.
When a DNS client sends such a request, the first responding server does not provide the needed IP address. Instead, it directs the request to another server that is lower in the DNS hierarchy, and that one to another until the IP address is fully resolved. There are a few stops in this process.
hierarchy looks like this (just for reference):
Root domain nameservers. Root servers themselves do not map IP addresses to domain names. Instead, they hold the information about all top-level domain (TLD) nameservers and point to their location. TLD is the rightmost section of a domain name... Root servers are critical since they are the first stop for all DNS lookup requests.
TLD nameservers. These servers contain the data for second-level domains, such as ‘phoenixnap’ in phoenixnap.com. Previously, the root server pointed to the location of the TLD server. Then, the TLD server needs to direct the request toward the server that contains the necessary data for the website we are trying to reach.
Authoritative nameserver. Authoritative servers are the final destination for DNS lookup requests. They provide the website’s IP address back to the recursive DNS servers. If the site has subdomains, the local DNS server will keep sending requests to the authoritative server until it finally resolves the IP address.
Step 5 - Receive the IP Address
Once the ISP’s recursive DNS server obtains the IP address by sending multiple iterative DNS queries, it finally returns it to your computer. The record for this request now stays cached on the hard drive. The browser can then fetch this IP from the cache and connect it to the website’s server.
ALL this happens in less than 1 second, most of the times. if you just registered a new domain it might take few hours to propagate this DNS cache globally hence newly registered websites do not show up sometimes.
About companies owning multiple IPs
Big companies have pool of IPs reserved for example 123.234.xxx.xxx which means a company has reserved 255*255 ips. they are mapped on a VPC(virtual private cloud)
and accessible vis a subnet masking and CIDR feature, like your EC2 instances on AWS
Is the IP that is resolved by the DNS server when I hit www.google.com is same as any of the Google router's Gateway IP?
For sure it should, but it is mostly a Google management question that only they will be able to answer right. The thing is that we must understand how DNS query's work for this.
Let's take a look of it:
Device A requests the IP address through a DNS query of the device B.
To do this, it uses the network port 53 (Domain) on which it will ask, depending on which DNS server is being used at the time, which is usually the home router. Then the router will ask the ISP's DNS server, which will respond with a cached response, or the query with another server on top of it if it does not have one; All this process is followed until a reliable cache response is reached or until the authoritative response server is reached, that is, the name server that manages the domain in question.
Only the authoritative response server contains the reliable information of which IP of the domain which is going to be reached.
I suppose that within Google's servers and its network they use Google's own DNS servers, which are 8.8.8.8 and 8.8.4.4 where the DNS records are obtained and consulted by caching from many sites.
In general terms Google's IP will change depending on where you are, I made a DIG query to Google's authoritative servers, however, I received a result based on location to improve the route and loading time of the site which was 142.250.73.238.
Do bigger companies like Amazon do port forwarding?
Yes, they do. To handle queries with load balancers or similar and even for caching dns requests.
If point 2 is true, I suppose they must be port forwarding with only 443 (https) port which means, to use multiple static IP across different data centers, they need to have that many routers. So, if they have N static IP address which resolves to a website, then they must be having N routers right? Is this a fair assumption?
This has multiple answers. By the way, they actually can do a secure DNS query.
if they have N static IP address which resolves to a website, then they must be having N routers right?
They don't have to, but if they want to they can.
"Is this a fair assumption?"
No, the IP's doesn't depend on a router, the router only routes to a computer/server which can have multiple IP's. By the other hand, each thing (computer, server, etc... must have an IP which can be also a WAN IP).
(I’m asking the question here because most of the other similar questions on StackExchange seem to be here — please let me know if there is a more appropriate community).
I have a number of computers on a network with a Linux Server running iptables, which is using Network Address Translation.
Not being an expert, I understand that the role of NAT is to take the internal 198 IP addresses, forward them to the external host under a common external IP address, and, when the response arrives, reverse the process.
If a number of internal machines make requests to the same external host, does this mean that host thinks they’re all coming from the same machine? What implications would that have for security or if the host wants to blacklist a machine?
"The router knows where packets belong because The router saves ... an address translation table. It remembers what inside-outside address translations it has made. As such, one inside address equals one outside address, and the out-on-the-internet destination is irrelevant. This, of course, ignores the firewall present in practically every NAT router, which tracks full connections:"
How NAT Port forwarding works
I am logging every user's IP when they access the company's page.
There are two ways to access the page from inside the local network:
http://company/webpage
and
https://webpage.company.com
What bugs me is that even when the users use the https global IP, their accesses are still recorded on database with their IP as 10.50.1.12 or 10.50.1.100.
Does that means that the browser or something else is redirecting the https://webpage.company.com to company/webpage? Or does that mean that I'm using a flawed method to log the users IP?
Another way to ask my question (just to make sure I'm being clear): if I'm accessing my Internet web page from inside the LAN network, am I effectively going outside my network and then back? If not, where am I going wrong with my logging?
Code used to log user's IP:
user.LastIP = HttpContext.Current.Request.UserHostAddress;
I'm curious about this because I want to make sure the users inside the company will access the page using exclusively the LAN Network. The goal is to save bandwidth usage, which is scarce.
Edit:
Pinging the https://webpage.company.com from inside the LAN network will result in a reply from a global IP address like 194.xxx.xxx.xxx. So I'm clearly getting the user's IP wrongly. What would be the ideal way of retrieving the IP from the page accessing entity?
Access to http://company/webpage will result in a DNS lookup of the host name "company". To resolve this, DNS will need a fully qualified domain name (fqdn), so it will add a top level domain (according to the configured search list in the client). In this example, it seems fair to assume that the fqdn will be "company.com". This, in turn, may very well resolve to the same IP address as the "webpage.company.com". You can check this by using dns lookup utilities like 'nslookup' and 'dig', or simply by using 'ping company' and 'ping webpage.company.com'.
The users IP addresses you mention, 10.50.1.12 and 10.50.1.100, seems to be the local IP addresses of the client hosts. I base this assumption on the fact that these IP addresses come from the RFC-1918 address range which is used for internal addresses. My guess is that these are the correct IP addresses, and that your logging works fine.
The users IP address you will log from accessing 'http://company/webpage' and 'https://webpage.company.com' should in most cases be the same. You can see it this way: it doesn't matter what the target URL is, traffic is still coming from the same host, the same IP address.
In any case, you most probably don't need to worry about any traffic leaving your local network.
I have a static local IP Address: 10.8.4., and the public IP Address of my machine is: 72.43.135.. when the server(sitting on different network from my workstation) gets a request from my machine, it sees my IP address from
Context.Request.UserHostAddress
and got 10.20.102.*.
why it the server not getting the IP as: 72.43.135.*?
If you define public and local, you will get to know that these terms might refere to the same network under some conditions. This could be a demilitarized zone (DMZ) for example.
What IP the destination server sees, depends on the interface you send the packets through and the routers it crosses.
Is there masquerading (NAT) ? - Is the main question. You can be on totally different networks but the routers might still forward your local IP, now this also depends on the routing table. Can a packet find its way back to your host? Is there a reversed route from the host to your machine?
The destination host is propably having 2 interfaces, 1 with IP 72.43.. one with a 10.8.. maybe it recieves through the 72 but sends back through the 10.8 because it has a different route back. Networking can be real voodoo! Trace your packets, ask your sysadmins..
(not talking about proxies here, they deliver different custom headers with different IPs)