Could someone explain IPv6?
by mfoley from LinuxQuestions.org on (#6D0WF)
I've never messed with IPv6 IPs, but I've been forced to lately. Gmail was blocking my messages:
Code:<<< 550-5.7.1 [2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1 12] Our system has
<<< 550-5.7.1 detected that this message is likely unsolicited mail.It has my server's IPv6 address in this rejection message, not the IPv4 address. When I added this IPv6 address to the SPF record, all was well.
Also, I recently had this IPv6 address blacklisted on spamhaus. I was able to get it unblocked.
So, I need to consider IPv6 addresses in configurations, even if this and other of my servers don't use IPv6 addresses. Apparently one automatically gets an IPv6 address automatically, perhaps depending on the ISP.
Both Gmail and Spamhaus specifically listed the IPv6 address they didn't like. When I look up the IPv6 address on this server, I get:
Code:# ip -6 addr
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1/64 scope global mngtmpaddr dynamic
valid_lft 437934sec preferred_lft 437934sec
inet6 fe80::f66d:4ff:fe5f:ffd1/64 scope link
valid_lft forever preferred_lft foreverFirst point of confusion, two inet6 addresses are listed:
2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1/64 scope global mngtmpaddr
fe80::f66d:4ff:fe5f:ffd1/64 scope link
The last 4 "octets" are the same (are these still called "octets"?). The 1st address has 8 octets. The 2nd has only 6 groups with an empty 2nd group. Why are there two addresses and what do these differences mean?
Searching for info on the "scope" attribute I found:
Quote:
So is the address with the 6 octets-empty-2nd-octet something like the IPv4 netmask?
I have another server, same Linux distro on the same Spectrum assigned IPv4 address range, sitting right next to the server described above. It has a different domain name. I want to add its IPv6 address to its SPF record. When I run ip -6 addr I get:
Code:# ip -6 addr
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 fe80::468a:5bff:fe89:1d7f/64 scope link
valid_lft forever preferred_lft foreverIn this case, there in no IPv6 address with 8 octets. Why? Note that net.ipv6.conf.all.disable_ipv6 = 0.
Apparently it's the 8 octet version that is seen publicly, so I don't think I can add the one shown to the SPF. Where's my 8-octet IPv6 address on this server?
Code:<<< 550-5.7.1 [2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1 12] Our system has
<<< 550-5.7.1 detected that this message is likely unsolicited mail.It has my server's IPv6 address in this rejection message, not the IPv4 address. When I added this IPv6 address to the SPF record, all was well.
Also, I recently had this IPv6 address blacklisted on spamhaus. I was able to get it unblocked.
So, I need to consider IPv6 addresses in configurations, even if this and other of my servers don't use IPv6 addresses. Apparently one automatically gets an IPv6 address automatically, perhaps depending on the ISP.
Both Gmail and Spamhaus specifically listed the IPv6 address they didn't like. When I look up the IPv6 address on this server, I get:
Code:# ip -6 addr
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1/64 scope global mngtmpaddr dynamic
valid_lft 437934sec preferred_lft 437934sec
inet6 fe80::f66d:4ff:fe5f:ffd1/64 scope link
valid_lft forever preferred_lft foreverFirst point of confusion, two inet6 addresses are listed:
2603:6011:2d02:ee82:f66d:4ff:fe5f:ffd1/64 scope global mngtmpaddr
fe80::f66d:4ff:fe5f:ffd1/64 scope link
The last 4 "octets" are the same (are these still called "octets"?). The 1st address has 8 octets. The 2nd has only 6 groups with an empty 2nd group. Why are there two addresses and what do these differences mean?
Searching for info on the "scope" attribute I found:
Quote:
| The IPv6 addresses fall under three scopes-global, link-local, and unique local. Global: An address that has an unlimited scope. Link-local: An address with a link-only scope that can be used to reach neighboring nodes attached to the same link. This address is automatically assigned to a network interface. |
I have another server, same Linux distro on the same Spectrum assigned IPv4 address range, sitting right next to the server described above. It has a different domain name. I want to add its IPv6 address to its SPF record. When I run ip -6 addr I get:
Code:# ip -6 addr
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
inet6 fe80::468a:5bff:fe89:1d7f/64 scope link
valid_lft forever preferred_lft foreverIn this case, there in no IPv6 address with 8 octets. Why? Note that net.ipv6.conf.all.disable_ipv6 = 0.
Apparently it's the 8 octet version that is seen publicly, so I don't think I can add the one shown to the SPF. Where's my 8-octet IPv6 address on this server?