Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

I'm facing a situation where one app(using ssh) can connect from Machine A (Linux) to Machine B (windows), whereas Machine A cannot ping Machine B. Another app on Machine A which connects to Machine B (not using ssh) is also failing to connect

Can someone please tell me the reasons for the same? I suspect a firewall issue. Can this be due to a firewall? If so why does ssh still connect? Also how do I check for blocked ports and unblock the same?

Adding more information. Sorry for not providing the same before. I'm using a Windows 7 operating system. Running netsh advfirewall firewall returns The service has not been started.
It's on a company network so I'm sure there must be an external firewall which I would not be able to modify.

share|improve this question
    
You doesnt say 1. Which OS you run 2. Type of firewall 3. List of firewall rules. –  Korjavin Ivan Sep 15 '11 at 6:43
    
Please edit your question to include more information, such as the operating systems that these machines are running. It's difficult to give specific answers to overly broad questions. –  Handyman5 Sep 15 '11 at 6:45
    
I'm sorry about being so generic. I'm new to this and will provide as much information as I can. I've added some info to the question. Please let me know if you require more information. I'm looking at understanding the behavior. –  StuckAgain Sep 15 '11 at 7:01
    
I've added the information to the question. Due to the external firewall, I'm not sure if it will answer your questions. If you do have any explanations for such behavior (ssh connects and ping fails), please provide some details on the same. –  StuckAgain Sep 15 '11 at 7:03
    
What OS is running on the machines? Is there a firewall between the two machines ? –  Iain Sep 15 '11 at 7:06

2 Answers 2

Sounds like the Windows firewall isn't starting. If you can't get the Windows firewall up and running (even if the firewall itself is disabled the service still needs to be running) then you won't be able to ping (or do much else on the network).

share|improve this answer
    
I guess my Windows firewall is disabled. But that should allow me to perform all activities on the network right?? I do have an external firewall whose configuration I don't have access to. –  StuckAgain Sep 15 '11 at 8:42
    
Nope, when the Windows firewall isn't working Windows defaults no basically nothing working on the network. This is different from the old way in Windows XP or Vista when it defaulted to allowing everything. –  mrdenny Sep 15 '11 at 8:44

i think it is a firewall issue wich operating system you use?=

if linux is your operating system : Type
sudo iptables -L if there is anything like

DROP icmp -- anywhere localhost

sudo iptables -D INPUT "n"

n = the number of your iptable rule find in (iptables -L).. first one 2nd one ...

if your operating system is Mircrosoft check your internal firewall/s

Greez Bull

share|improve this answer
    
I've provided the details in the questions. Don't think I can do much with the firewall as it is for a network. Is there any way I can confirm the firewall issue from my side?? Also why would ssh succeed?? Would it be excluded from the same?? –  StuckAgain Sep 15 '11 at 7:05
    
there are (arguably) 3 main protocols on the IPv4 stack. TCP, this is a reliable protocol and ensures delivery at the cost of speed, this is what SSH and most programs use. Pings are part of the ICMP protocol, its a completely different protocol to TCP and is treated differently. it requires that there be a program running on both sides to respond to ICMP requests, ICMP is for diagnostics and not data transmission, you can not send data with ICMP. UDP is the 3rd, it is fast but potentially unreliable, it is fairly similar to TCP but does not ensure delivery. many people block ICMP for security –  Silverfire Sep 15 '11 at 7:13
    
@Silverfire: Thanks a lot for the reply. It makes things clearer to me. However I do have another app which is using another port (non-SSH). Even that app cannot connect. Could it be that everything is kinda blocked?? And that ssh has some special privileges?? Or the firewall rules allow the ssh port to be unblocked??? –  StuckAgain Sep 15 '11 at 7:19
    
firewall from the sounds of it. Port 22 (ssh) is considered a pretty important port for most servers as it is the primary form of administration. Are you running through a proxy by any chance? ive seen sys-admins deny all traffic but web (through http proxy) and ssh (for admin reasons). check both the target and host firewalls. –  Silverfire Sep 15 '11 at 7:24
    
@Silverfire: Thanks, that does make sense. Unfortunately, I don't think I have access to the firewalls, so won't be able to check the same. Is there anyway to find out whether a port is blocked?? From command line for windows?? Also, can you please frame you comments as an answer?? It clarifies most of my questions and I'll accept it –  StuckAgain Sep 15 '11 at 7:43

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.