I've just got a powerful dedicated server, and I'd like to virtualize it. The idea is to install Proxmox VE on the host and then create a VM for each use: one for my website, one for mi Git repo, and so on.

I just began fiddling around with iptables, and I have to admit I'm having a bad time. I composed a tiny script:


# Empty any existing rule
iptables -F
iptables -t nat -F
iptables -t mangle -F

# Remove personnal chains
iptables -X
iptables -t nat -X
iptables -t mangle -X

# Enable ESTABLISHED and RELATED communications, accepts answers
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A OUTPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

# Enable ping
iptables -A OUTPUT -p icmp -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -p icmp -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -p icmp -m limit --limit 5/s -j ACCEPT

# Enable remote acccess through SSH
iptables -A INPUT -p TCP --dport ssh -j ACCEPT
iptables -A INPUT -p TCP --dport http -j ACCEPT

iptables -A OUTPUT -p udp --dport 53 -j ACCEPT
iptables -A OUTPUT -p tcp --dport 53 -j ACCEPT

# Web output (HTTP & HTTPS)
iptables -I INPUT -p tcp --dport 80 -j ACCEPT
iptables -I INPUT -p tcp --dport 443 -j ACCEPT

# Open ports for proxmox input
iptables -I INPUT -p tcp --dport 8006 -j ACCEPT
iptables -I INPUT -p tcp --dport 5900 -j ACCEPT
iptables -I INPUT -p tcp --dport 5999 -j ACCEPT
iptables -I INPUT -p tcp --dport 3128 -j ACCEPT

# Default to DROP
iptables -P INPUT DROP
iptables -P OUTPUT DROP
iptables -P FORWARD DROP

Here, no flux routing yet. My aim is, first, to open all the ports needed for proxmox to work correctly on a safe environment.

Once that script's executed, I can display proxmox's Web UI (8006), but cannot log. Proxmox says "Login failed, please try again". When all the rules are flushed away ,everything works fine.

Can someone help?

1 Answer 1


You should have a rule to accept everything on the loopback device so internal communication is not blocked by iptables.

iptables -I INPUT -i lo -j ACCEPT
iptables -I OUTPUT -o lo -j ACCEPT

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