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So I've encountered a weird problem when trying to set up a Linux server running a variant of CRUX Linux. I am trying to configure it to be a Teamspeak server, but no clients can connect. The machine is on, I can SSH into it and access HTTP(S) services, and another TCP server program but I cannot ping the machine except from itself. The box is set to respond to ICMP requests, and this is the result of iptables:

Chain INPUT (policy DROP)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:ssh 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:http 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:25565 
ACCEPT     all  --  anywhere             anywhere            state RELATED,ESTABLISHED 
ACCEPT     tcp  --  anywhere             anywhere            tcp dpt:https 

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination

I have also tried adding an explicit rule to iptables for the port for teamspeak (9987) using:

iptables -A INPUT -p udp -s 0/0 --dport 9987 -j ACCEPT

but this makes no difference to the ability to connect.

It seems like this is a network problem, but it's weird since the computer has an internet connection; it can ping other machines on the network; and I can access some of the services on it, but not, it seems, ICMP or UDP ones.

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closed as unclear what you're asking by Jeff Schaller, garethTheRed, Anthon, jimmij, cuonglm Jun 8 at 3:45

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question.If this question can be reworded to fit the rules in the help center, please edit the question.

1  
Save your iptable rules. Flush iptalbes and try ping and connect to udp service. post netstat -lepunt – Manula Waidyanatha Sep 11 '12 at 4:08
2  
What's the output of iptables -nvL? That first rule looks weird: is it really accepting everything, or only everything on the loopback interface? If the latter, you have no rule allowing incoming UDP. – Gilles Sep 12 '12 at 1:40
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If you add that rule for port 9987, does the usage counter increase when you make connection attempts? – Gilles Sep 12 '12 at 1:41
    
Your INPUT policy is "DROP", so anything not matched by any of the rules above will be dropped. We'd need the -v option to iptables to see what the first INPUT rule is. Or better, show the output of iptables-save. Their may also be something interesting in the nat and mangle tables. – Stéphane Chazelas Sep 17 '12 at 22:16

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