I'm giving Linode a try, and I just launched my first instance running CentOS. I've been unable to connect to a port on the box even if I completely drop the firewall. (My script does successfully connect over localost, just not from an external machine)
Here's some info:
# iptables -n -L -v --line-numbers Chain INPUT (policy ACCEPT 580 packets, 45519 bytes) num pkts bytes target prot opt in out source destination Chain FORWARD (policy ACCEPT 0 packets, 0 bytes) num pkts bytes target prot opt in out source destination Chain OUTPUT (policy ACCEPT 482 packets, 78913 bytes) num pkts bytes target prot opt in out source destination
nat / raw
iptables -t nat -L Chain PREROUTING (policy ACCEPT) target prot opt source destination Chain INPUT (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain POSTROUTING (policy ACCEPT) target prot opt source destination
netstat: I'm listening on port 6034:
netstat -tulpn Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:6034 0.0.0.0:* LISTEN 5845/python tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 2026/sshd tcp 0 0 :::22 :::* LISTEN 2026/sshd udp 0 0 0.0.0.0:68 0.0.0.0:* 1896/dhclient
lsof: Again, port 6034:
lsof -i COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME python 5845 apiuser 3u IPv4 4621 0t0 TCP *:6034 (LISTEN)
nmap scan shows 'filtered' state (IP addr scrubbed below)
nmap -p 6034 126.96.36.199 Starting Nmap 6.40 ( http://nmap.org ) at 2014-04-02 09:31 EDT Nmap scan report for ftd.fasttrackdispatch.com (188.8.131.52) Host is up (0.030s latency). PORT STATE SERVICE 6034/tcp filtered unknown Nmap done: 1 IP address (1 host up) scanned in 0.40 seconds
Edit: Per LinuxDevOps's suggestion, I ran tcpdump on that port while trying to connect. It doesn't show any traffic whatsoever.
Again, I can connect over localhost, but not from an external box. Also, I've tried making the connection from different machines on different networks and still no luck. Any ideas what the problem could be or what I should try next?