ping IPv6 sendmsg: network is unreachable, not working on Linux

[AlexandreYang]

Describe the bug

Rshell behaviour, not working on LINUX:

rshell$ ping -6 dns.google.com
PING dns.google.com (2001:4860:4860::8844): 56 data bytes

--- dns.google.com ping statistics ---
0 packets transmitted, 0 received, 0.0% packet loss
ping: write ip ::->2001:4860:4860::8844: sendmsg: network is unreachable

Rshell behaviour for IPv6 works on macOS:

§ go run cmd/rshell/main.go --allow-all-commands  -c 'ping -6 dns.google.com'
PING dns.google.com (2001:4860:4860::8844): 56 data bytes
64 bytes from 2001:4860:4860::8844: icmp_seq=1 ttl=251 time=7.977 ms
64 bytes from 2001:4860:4860::8844: icmp_seq=2 ttl=251 time=7.458 ms
64 bytes from 2001:4860:4860::8844: icmp_seq=3 ttl=251 time=5.626 ms
64 bytes from 2001:4860:4860::8844: icmp_seq=4 ttl=251 time=6.406 ms

--- dns.google.com ping statistics ---
4 packets transmitted, 4 received, 0.0% packet loss
round-trip min/avg/max/stddev = 5.626/6.866/7.977/0.912 ms

MacOS ping6 behaviour (working):

ping6 -c 4 dns.google.com
PING6(56=40+8+8 bytes) 2a01:cb00:26c:1100:196a:45fb:784d:87d4 --> 2001:4860:4860::8844
16 bytes from 2001:4860:4860::8844, icmp_seq=0 hlim=251 time=7.370 ms
16 bytes from 2001:4860:4860::8844, icmp_seq=1 hlim=251 time=5.381 ms
16 bytes from 2001:4860:4860::8844, icmp_seq=2 hlim=251 time=4.675 ms
16 bytes from 2001:4860:4860::8844, icmp_seq=3 hlim=251 time=5.712 ms

--- dns.google.com ping6 statistics ---
4 packets transmitted, 4 packets received, 0.0% packet loss
round-trip min/avg/max/std-dev = 4.675/5.785/7.370/0.989 ms