How to prevent remote access to SSH 22 port, firewall rules

vgstech

vgstech

Renowned Member
Proxmox Subscriber
Apr 24, 2015
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vgst.net
HI,


I have a cluster with to machines on Proxmox 5.3-11 environment.

I know that port 22 it's needed to internal cluster communication, but I want to prevent remote access to this port. I added a second SSH port to allow remote login and works well. I have configured the firewall on cluster and nodes to deny SSH traffic from external networks, but still it's possible to access to SSH through 22 port, so, what I doing wrong?

This is the iptables config of one of the nodes:

Code: 
-P INPUT ACCEPT
-P FORWARD ACCEPT
-P OUTPUT ACCEPT
-N GROUP-cluster-IN
-N GROUP-cluster-OUT
-N PVEFW-Drop
-N PVEFW-DropBroadcast
-N PVEFW-FORWARD
-N PVEFW-FWBR-IN
-N PVEFW-FWBR-OUT
-N PVEFW-HOST-IN
-N PVEFW-HOST-OUT
-N PVEFW-INPUT
-N PVEFW-OUTPUT
-N PVEFW-Reject
-N PVEFW-SET-ACCEPT-MARK
-N PVEFW-logflags
-N PVEFW-reject
-N PVEFW-smurflog
-N PVEFW-smurfs
-N PVEFW-tcpflags
-A INPUT -j PVEFW-INPUT
-A FORWARD -j PVEFW-FORWARD
-A OUTPUT -j PVEFW-OUTPUT
-A GROUP-cluster-IN -j MARK --set-xmark 0x0/0x80000000
-A GROUP-cluster-IN -m set --match-set PVEFW-0-internal-v4 src -m set --match-set PVEFW-0-internal-v4 dst -g PVEFW-SET-ACCEPT-MARK
-A GROUP-cluster-IN -m comment --comment "PVESIG:35IwDfkTGykp7kuIhQYrmlQK9RQ"
-A GROUP-cluster-OUT -j MARK --set-xmark 0x0/0x80000000
-A GROUP-cluster-OUT -m comment --comment "PVESIG:QiNxnYp/kkUW2PbnPksDo1aXztU"
-A PVEFW-Drop -p tcp -m tcp --dport 43 -j PVEFW-reject
-A PVEFW-Drop -j PVEFW-DropBroadcast
-A PVEFW-Drop -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
-A PVEFW-Drop -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A PVEFW-Drop -m conntrack --ctstate INVALID -j DROP
-A PVEFW-Drop -p udp -m multiport --dports 135,445 -j DROP
-A PVEFW-Drop -p udp -m udp --dport 137:139 -j DROP
-A PVEFW-Drop -p udp -m udp --sport 137 --dport 1024:65535 -j DROP
-A PVEFW-Drop -p tcp -m multiport --dports 135,139,445 -j DROP
-A PVEFW-Drop -p udp -m udp --dport 1900 -j DROP
-A PVEFW-Drop -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -j DROP
-A PVEFW-Drop -p udp -m udp --sport 53 -j DROP
-A PVEFW-Drop -m comment --comment "PVESIG:WDy2wbFe7jNYEyoO3QhUELZ4mIQ"
-A PVEFW-DropBroadcast -m addrtype --dst-type BROADCAST -j DROP
-A PVEFW-DropBroadcast -m addrtype --dst-type MULTICAST -j DROP
-A PVEFW-DropBroadcast -m addrtype --dst-type ANYCAST -j DROP
-A PVEFW-DropBroadcast -d 224.0.0.0/4 -j DROP
-A PVEFW-DropBroadcast -m comment --comment "PVESIG:NyjHNAtFbkH7WGLamPpdVnxHy4w"
-A PVEFW-FORWARD -m conntrack --ctstate INVALID -j DROP
-A PVEFW-FORWARD -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A PVEFW-FORWARD -m physdev --physdev-in fwln+ --physdev-is-bridged -j PVEFW-FWBR-IN
-A PVEFW-FORWARD -m physdev --physdev-out fwln+ --physdev-is-bridged -j PVEFW-FWBR-OUT
-A PVEFW-FORWARD -m comment --comment "PVESIG:qnNexOcGa+y+jebd4dAUqFSp5nw"
-A PVEFW-FWBR-IN -m conntrack --ctstate INVALID,NEW -j PVEFW-smurfs
-A PVEFW-FWBR-IN -m comment --comment "PVESIG:Ijl7/xz0DD7LF91MlLCz0ybZBE0"
-A PVEFW-FWBR-OUT -m comment --comment "PVESIG:2jmj7l5rSw0yVb/vlWAYkK/YBwk"
-A PVEFW-HOST-IN -i lo -j ACCEPT
-A PVEFW-HOST-IN -m conntrack --ctstate INVALID -j DROP
-A PVEFW-HOST-IN -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A PVEFW-HOST-IN -m conntrack --ctstate INVALID,NEW -j PVEFW-smurfs
-A PVEFW-HOST-IN -p igmp -j RETURN
-A PVEFW-HOST-IN -m set --match-set PVEFW-0-internal-v4 src -m set --match-set PVEFW-0-internal-v4 dst -j RETURN
-A PVEFW-HOST-IN -p tcp -m tcp --dport 8006 -j RETURN
-A PVEFW-HOST-IN -p tcp -m tcp --dport 8090 -j RETURN
-A PVEFW-HOST-IN -m set --match-set PVEFW-0-no_internal-v4 src -j DROP
-A PVEFW-HOST-IN -j GROUP-cluster-IN
-A PVEFW-HOST-IN -m mark --mark 0x80000000/0x80000000 -j RETURN
-A PVEFW-HOST-IN -p tcp -m set --match-set PVEFW-0-management-v4 src -m tcp --dport 8006 -j RETURN
-A PVEFW-HOST-IN -p tcp -m set --match-set PVEFW-0-management-v4 src -m tcp --dport 5900:5999 -j RETURN
-A PVEFW-HOST-IN -p tcp -m set --match-set PVEFW-0-management-v4 src -m tcp --dport 3128 -j RETURN
-A PVEFW-HOST-IN -p tcp -m set --match-set PVEFW-0-management-v4 src -m tcp --dport 22 -j RETURN // < ---------- Problem??
-A PVEFW-HOST-IN -s X.X.X.0/24 -d X.X.X.0/24 -p udp -m udp --dport 5404:5405 -j RETURN
-A PVEFW-HOST-IN -s X.X.X.X/24 -p udp -m addrtype --dst-type MULTICAST -m udp --dport 5404:5405 -j RETURN
-A PVEFW-HOST-IN -j RETURN
-A PVEFW-HOST-IN -m comment --comment "PVESIG:bGq98TkuB/Z1+O7SsqGMkr4+KEg"
-A PVEFW-HOST-OUT -o lo -j ACCEPT
-A PVEFW-HOST-OUT -m conntrack --ctstate INVALID -j DROP
-A PVEFW-HOST-OUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
-A PVEFW-HOST-OUT -p igmp -j RETURN
-A PVEFW-HOST-OUT -j GROUP-cluster-OUT
-A PVEFW-HOST-OUT -m mark --mark 0x80000000/0x80000000 -j RETURN
-A PVEFW-HOST-OUT -d X.X.X.X/24 -p tcp -m tcp --dport 8006 -j RETURN
-A PVEFW-HOST-OUT -d X.X.X.X/24 -p tcp -m tcp --dport 22 -j RETURN
-A PVEFW-HOST-OUT -d X.X.X.X/24 -p tcp -m tcp --dport 5900:5999 -j RETURN
-A PVEFW-HOST-OUT -d X.X.X.X/24 -p tcp -m tcp --dport 3128 -j RETURN
-A PVEFW-HOST-OUT -d X.X.X.X/24 -p udp -m udp --dport 5404:5405 -j RETURN
-A PVEFW-HOST-OUT -p udp -m addrtype --dst-type MULTICAST -m udp --dport 5404:5405 -j RETURN
-A PVEFW-HOST-OUT -j RETURN
-A PVEFW-HOST-OUT -m comment --comment "PVESIG:83FUEKuA1BtYAGvdoEhalC1itoE"
-A PVEFW-INPUT -j PVEFW-HOST-IN
-A PVEFW-INPUT -m comment --comment "PVESIG:+5iMmLaxKXynOB/+5xibfx7WhFk"
-A PVEFW-OUTPUT -j PVEFW-HOST-OUT
-A PVEFW-OUTPUT -m comment --comment "PVESIG:LjHoZeSSiWAG3+2ZAyL/xuEehd0"
-A PVEFW-Reject -p tcp -m tcp --dport 43 -j PVEFW-reject
-A PVEFW-Reject -j PVEFW-DropBroadcast
-A PVEFW-Reject -p icmp -m icmp --icmp-type 3/4 -j ACCEPT
-A PVEFW-Reject -p icmp -m icmp --icmp-type 11 -j ACCEPT
-A PVEFW-Reject -m conntrack --ctstate INVALID -j DROP
-A PVEFW-Reject -p udp -m multiport --dports 135,445 -j PVEFW-reject
-A PVEFW-Reject -p udp -m udp --dport 137:139 -j PVEFW-reject
-A PVEFW-Reject -p udp -m udp --sport 137 --dport 1024:65535 -j PVEFW-reject
-A PVEFW-Reject -p tcp -m multiport --dports 135,139,445 -j PVEFW-reject
-A PVEFW-Reject -p udp -m udp --dport 1900 -j DROP
-A PVEFW-Reject -p tcp -m tcp ! --tcp-flags FIN,SYN,RST,ACK SYN -j DROP
-A PVEFW-Reject -p udp -m udp --sport 53 -j DROP
-A PVEFW-Reject -m comment --comment "PVESIG:CZJnIN6rAdpu+ej59QPr9+laMUo"
-A PVEFW-SET-ACCEPT-MARK -j MARK --set-xmark 0x80000000/0x80000000
-A PVEFW-SET-ACCEPT-MARK -m comment --comment "PVESIG:Hg/OIgIwJChBUcWU8Xnjhdd2jUY"
-A PVEFW-logflags -j DROP
-A PVEFW-logflags -m comment --comment "PVESIG:MN4PH1oPZeABMuWr64RrygPfW7A"
-A PVEFW-reject -m addrtype --dst-type BROADCAST -j DROP
-A PVEFW-reject -s 224.0.0.0/4 -j DROP
-A PVEFW-reject -p icmp -j DROP
-A PVEFW-reject -p tcp -j REJECT --reject-with tcp-reset
-A PVEFW-reject -p udp -j REJECT --reject-with icmp-port-unreachable
-A PVEFW-reject -p icmp -j REJECT --reject-with icmp-host-unreachable
-A PVEFW-reject -j REJECT --reject-with icmp-host-prohibited
-A PVEFW-reject -m comment --comment "PVESIG:Jlkrtle1mDdtxDeI9QaDSL++Npc"
-A PVEFW-smurflog -j DROP
-A PVEFW-smurflog -m comment --comment "PVESIG:2gfT1VMkfr0JL6OccRXTGXo+1qk"
-A PVEFW-smurfs -s 0.0.0.0/32 -j RETURN
-A PVEFW-smurfs -m addrtype --src-type BROADCAST -g PVEFW-smurflog
-A PVEFW-smurfs -s 224.0.0.0/4 -g PVEFW-smurflog
-A PVEFW-smurfs -m comment --comment "PVESIG:HssVe5QCBXd5mc9kC88749+7fag"
-A PVEFW-tcpflags -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG FIN,PSH,URG -g PVEFW-logflags
-A PVEFW-tcpflags -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -g PVEFW-logflags
-A PVEFW-tcpflags -p tcp -m tcp --tcp-flags SYN,RST SYN,RST -g PVEFW-logflags
-A PVEFW-tcpflags -p tcp -m tcp --tcp-flags FIN,SYN FIN,SYN -g PVEFW-logflags
-A PVEFW-tcpflags -p tcp -m tcp --sport 0 --tcp-flags FIN,SYN,RST,ACK SYN -g PVEFW-logflags
-A PVEFW-tcpflags -m comment --comment "PVESIG:CMFojwNPqllyqD67NeI5m+bP5mo"

I attached a screenshot of the GUI firewall config too.


Thanks
 

Attachments

  • firewall_rules.png
    firewall_rules.png
    19.6 KB · Views: 3
Hi,

how do you config the second port for ssh?
 
wolfgang said:
Hi,

how do you config the second port for ssh?
Click to expand...

With a second port, like that:


Code: 
#       $OpenBSD: sshd_config,v 1.100 2016/08/15 12:32:04 naddy Exp $

# This is the sshd server system-wide configuration file.  See
# sshd_config(5) for more information.

# This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin

# The strategy used for options in the default sshd_config shipped with
# OpenSSH is to specify options with their default value where
# possible, but leave them commented.  Uncommented options override the
# default value.

Port 22
Port XXXX

Both ports works correctly.
 
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