DNS names not resolved, iptables problem?

Question

linux

Help me understand why DNS names are not resolved when you ping, for example, to ya.ru:

# ping ya.ru
ping: ya.ru: Имя или служба не известны

Customized rules:

#  iptables -L -v -n
Chain INPUT (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
   22  1446 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
    0     0 LOG        all  --  enp0s3 *       0.0.0.0/0            0.0.0.0/0            LOG flags 0 level 4 prefix "--- INPUT enp0s3 --- "
    0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0            state INVALID
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:!0x17/0x02 state NEW
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 0
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 3
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 11
    0     0 ACCEPT     icmp --  *      *       0.0.0.0/0            0.0.0.0/0            icmptype 8
   40  2880 ACCEPT     tcp  --  enp0s8 *       0.0.0.0/0            0.0.0.0/0            tcp dpt:22
    0     0 ACCEPT     tcp  --  enp0s8 *       0.0.0.0/0            0.0.0.0/0            tcp dpt:10050
    0     0 ACCEPT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            udp dpt:53
    0     0 ACCEPT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp dpt:53
    0     0 ACCEPT     udp  --  enp0s8 *       0.0.0.0/0            0.0.0.0/0            udp dpt:123
   12  4383 ACCEPT     tcp  --  enp0s8 *       0.0.0.0/0            0.0.0.0/0            tcp dpt:80
   82  6179 undef_in   all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain FORWARD (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    0     0 TCPMSS     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:0x06/0x02 TCPMSS clamp to PMTU
    0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0            state INVALID
    0     0 undef_fw   all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain OUTPUT (policy DROP 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
   22  1446 ACCEPT     all  --  *      lo      0.0.0.0/0            0.0.0.0/0
    0     0 ACCEPT     all  --  *      enp0s3  0.0.0.0/0            0.0.0.0/0
   34 13674 ACCEPT     all  --  *      enp0s8  0.0.0.0/0            0.0.0.0/0
    0     0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:!0x17/0x02 state NEW
    0     0 undef_out  all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain undef_fw (1 references)
 pkts bytes target     prot opt in     out     source               destination
    0     0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0            LOG flags 0 level 6 prefix "-- FW -- DROP "
    0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain undef_in (1 references)
 pkts bytes target     prot opt in     out     source               destination
   82  6179 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0            LOG flags 0 level 6 prefix "-- IN -- DROP "
   82  6179 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0

Chain undef_out (1 references)
 pkts bytes target     prot opt in     out     source               destination
    0     0 LOG        all  --  *      *       0.0.0.0/0            0.0.0.0/0            LOG flags 0 level 6 prefix "-- OUT -- DROP "
    0     0 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0

Log after ping:

May 30 21:15:48 srv kernel: --- INPUT enp0s3 --- IN=enp0s3 OUT= MAC=08:00:27:e2:3e:be:80:26:89:0d:41:0d:08:00 SRC=192.168.0.1 DST=192.168.0.100 LEN=63 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=53 DPT=51772 LEN=43
May 30 21:15:48 srv kernel: -- IN -- DROP IN=enp0s3 OUT= MAC=08:00:27:e2:3e:be:80:26:89:0d:41:0d:08:00 SRC=192.168.0.1 DST=192.168.0.100 LEN=63 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=53 DPT=51772 LEN=43
May 30 21:15:54 srv kernel: --- INPUT enp0s3 --- IN=enp0s3 OUT= MAC=08:00:27:e2:3e:be:80:26:89:0d:41:0d:08:00 SRC=8.8.8.8 DST=192.168.0.100 LEN=138 TOS=0x00 PREC=0x00 TTL=101 ID=20587 PROTO=UDP SPT=53 DPT=37955 LEN=118
May 30 21:15:54 srv kernel: -- IN -- DROP IN=enp0s3 OUT= MAC=08:00:27:e2:3e:be:80:26:89:0d:41:0d:08:00 SRC=8.8.8.8 DST=192.168.0.100 LEN=138 TOS=0x00 PREC=0x00 TTL=101 ID=20587 PROTO=UDP SPT=53 DPT=37955 LEN=118

If you apply the rule:
iptables -A INPUT -i enp0s3 -j ACCEPT
Then the problem goes away, pings pass, but since interface enp0s3 looks at the Internet, it's not very good...

Answer 1

Add and check

iptables -I INPUT 1 -m state --state ESTABLISHED,RELATED -j ACCEPT