How to transparent proxy Linux's UDP traffic (DNS queries) using iptables?
I run dnscrypt-proxy or tor on Linux listning on port 1053 for DNS.
I googled a lot and find two ways to do a transparent DNS proxy for Linux host:
iptables -t nat -I OUTPUT -j REDIRECT -p udp --dport 53 --to-ports 1053
or
iptables -t nat -I OUTPUT -j DNAT -p udp --dport 53 --to 127.0.0.1:1053
None of them work. My browser can't open webs, and nslookup and dig says
except x.x.x.x(DNS in /etc/resolv.conf) but get response from x.x.x.x#1053(host's IP)
dnscrypt-proxy also provide tcp port. With above iptables rules to proxy tcp, dig +tcp can get a correct response.
UDP is stateless, is that a limitation to iptables? But, transparent-proxying other hosts' UDP works:
iptables -t nat -I PREROUTING -d ${this_host} -p udp -m udp --dport 53 -j REDIRECT --to-ports 1053
(Linux act as gateway, to clients DNS response is from the right IP, but different port, and clients ignore port?)
iptables nat udp
asked 10 mins ago
garywill
313
add a comment |
I run dnscrypt-proxy or tor on Linux listning on port 1053 for DNS.
I googled a lot and find two ways to do a transparent DNS proxy for Linux host:
iptables -t nat -I OUTPUT -j REDIRECT -p udp --dport 53 --to-ports 1053
or
iptables -t nat -I OUTPUT -j DNAT -p udp --dport 53 --to 127.0.0.1:1053
None of them work. My browser can't open webs, and nslookup and dig says
except x.x.x.x(DNS in /etc/resolv.conf) but get response from x.x.x.x#1053(host's IP)
dnscrypt-proxy also provide tcp port. With above iptables rules to proxy tcp, dig +tcp can get a correct response.
UDP is stateless, is that a limitation to iptables? But, transparent-proxying other hosts' UDP works:
iptables -t nat -I PREROUTING -d ${this_host} -p udp -m udp --dport 53 -j REDIRECT --to-ports 1053
(Linux act as gateway, to clients DNS response is from the right IP, but different port, and clients ignore port?)
iptables nat udp
asked 10 mins ago
garywill
313
add a comment |
I run dnscrypt-proxy or tor on Linux listning on port 1053 for DNS.
I googled a lot and find two ways to do a transparent DNS proxy for Linux host:
iptables -t nat -I OUTPUT -j REDIRECT -p udp --dport 53 --to-ports 1053
or
iptables -t nat -I OUTPUT -j DNAT -p udp --dport 53 --to 127.0.0.1:1053
None of them work. My browser can't open webs, and nslookup and dig says
except x.x.x.x(DNS in /etc/resolv.conf) but get response from x.x.x.x#1053(host's IP)
dnscrypt-proxy also provide tcp port. With above iptables rules to proxy tcp, dig +tcp can get a correct response.
UDP is stateless, is that a limitation to iptables? But, transparent-proxying other hosts' UDP works:
iptables -t nat -I PREROUTING -d ${this_host} -p udp -m udp --dport 53 -j REDIRECT --to-ports 1053
(Linux act as gateway, to clients DNS response is from the right IP, but different port, and clients ignore port?)
iptables nat udp
asked 10 mins ago
garywill
313
I run dnscrypt-proxy or tor on Linux listning on port 1053 for DNS.
I googled a lot and find two ways to do a transparent DNS proxy for Linux host:
iptables -t nat -I OUTPUT -j REDIRECT -p udp --dport 53 --to-ports 1053
or
iptables -t nat -I OUTPUT -j DNAT -p udp --dport 53 --to 127.0.0.1:1053
None of them work. My browser can't open webs, and nslookup and dig says
except x.x.x.x(DNS in /etc/resolv.conf) but get response from x.x.x.x#1053(host's IP)
dnscrypt-proxy also provide tcp port. With above iptables rules to proxy tcp, dig +tcp can get a correct response.
UDP is stateless, is that a limitation to iptables? But, transparent-proxying other hosts' UDP works:
iptables -t nat -I PREROUTING -d ${this_host} -p udp -m udp --dport 53 -j REDIRECT --to-ports 1053
(Linux act as gateway, to clients DNS response is from the right IP, but different port, and clients ignore port?)
iptables nat udp
iptables nat udp
asked 10 mins ago
garywill
313
asked 10 mins ago
garywill
313
asked 10 mins ago
garywill
313
asked 10 mins ago
garywill
313
asked 10 mins ago
garywill
313
313
add a comment |
add a comment |
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