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The following ip6tables block thunderbird from retrieving email from my gmail account:

sudo ip6tables -P FORWARD DROP
sudo ip6tables -P INPUT DROP
sudo ip6tables -P OUTPUT DROP

sudo ip6tables -A INPUT  -j ACCEPT -i lo 
sudo ip6tables -A OUTPUT -j ACCEPT -o lo 

sudo ip6tables -A INPUT  -j ACCEPT -m conntrack --ctstate ESTABLISHED,RELATED
sudo ip6tables -A OUTPUT -j ACCEPT -m conntrack --ctstate ESTABLISHED,RELATED

sudo ip6tables -A INPUT -p icmpv6 -j ACCEPT 
sudo ip6tables -A OUTPUT -p icmpv6 -j ACCEPT

sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 53  -m comment --comment "DNS/TCP"
sudo ip6tables -A OUTPUT -j ACCEPT -p udp --dport 53  -m comment --comment "DNS/UDP"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 22  -m comment --comment "SSH secure shell"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 80  -m comment --comment "HTTP"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 443 -m comment --comment "HTTPS"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 110 -m comment --comment "POP3"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 143 -m comment --comment "IMAP"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 993 -m comment --comment "IMAP/SSL"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 25  -m comment --comment "SMTP"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 26  -m comment --comment "SMTP 2nd"
sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 465 -m comment --comment "SMTP/SSL"

Whenever I disable them, thunderbird can retrieve email fine. What am I doing wrong?

light9876
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  • At which stage is Thunderbird failing when trying to retrieve email? – a3nm Apr 25 '20 at 06:54
  • Have you tried using the `LOG` feature of iptables to log which packets are being dropped? (you might be able to filter specifically thunderbird's packet if you run it as a different user and filter on that) – a3nm Apr 25 '20 at 06:56
  • I repeatedly get this message: `Apr 25 10:53:30 user kernel: message_out_ipv6:IN= OUT=enp0s31f6 SRC=fe80:0000:0000:0000:5fe0:8278:e978:29a1 DST=ff02:0000:0000:0000:0000:0000:0000:0002 LEN=48 TC=0 HOPLIMIT=255 FLOWLBL=587658 PROTO=ICMPv6 TYPE=133 CODE=0` I can't figure out what it means.. – light9876 Apr 25 '20 at 09:55
  • May be this one? `Apr 25 10:56:33 user kernel: message_in_ipv6:IN=enp0s31f6 OUT= MAC=33:33:00:00:00:01:c4:71:fe:8c:67:7f:86:dd SRC=fe80:0000:0000:0000:c671:feff:fe8c:677f DST=ff02:0000:0000:0000:0000:0000:0000:0001 LEN=72 TC=224 HOPLIMIT=2>` – light9876 Apr 25 '20 at 09:57
  • Please show the complete firewall, with `ip6tables -nvL`. – Michael Hampton Jul 31 '20 at 21:49

1 Answers1

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What you see on logs or tcpdump? From other side some of Thunderbird and gmail tutorials (like https://oit.colorado.edu/tutorial/gmail-configure-thunderbird) suggest that it communicate with vendor site also on: Server hostname: smtp.gmail.com Port: 587 SSL: STARTTLS Authentication: Normal Password

Ziemek Borowski
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  • `sudo ip6tables -A OUTPUT -j ACCEPT -p tcp --dport 587` did not solve it.. – light9876 Apr 25 '20 at 06:35
  • Still - please check what you see in logs or TCPdump as first method. – Ziemek Borowski Apr 25 '20 at 07:38
  • I'm getting this message `Apr 25 10:53:30 user kernel: message_out_ipv6:IN= OUT=enp0s31f6 SRC=fe80:0000:0000:0000:5fe0:8278:e978:29a1 DST=ff02:0000:0000:0000:0000:0000:0000:0002 LEN=48 TC=0 HOPLIMIT=255 FLOWLBL=587658 PROTO=ICMPv6 TYPE=133 CODE=0` – light9876 Apr 25 '20 at 09:56